Late Effects of Treatment for Childhood Cancer (PDQ®): Treatment - Health Professional Information [NCI]

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General Information About Late Effects of Treatment for Childhood Cancer

During the past five decades, dramatic progress has been made in the development of curative therapies for pediatric malignancies. More than 80% of children with cancer who have access to contemporary therapies are expected to survive into adulthood.[1] The therapies responsible for this survival can also produce adverse, long-term, health-related outcomes, referred to as late effects, which appear months to years after completion of cancer treatment.

Many approaches have been used to study the very long-term morbidity associated with childhood cancer and its contribution to early mortality. These initiatives have used a spectrum of resources, including data from the following:

  • Population-based registries.[2,3]
  • Self-reported outcomes (provided through large-scale cohort studies).[4,5]
  • Medical assessments.[6,7,8]

High-quality data is needed to establish the occurrence of and risk profiles for late cancer treatment–related toxicity. The highest quality data typically comes from studies that report outcomes in survivors who have undergone medical assessments that provide well-characterized clinical statuses, treatment exposures, and specific late effects. Regardless of study methodology, it is important to consider selection and participation bias of the cohort studies in the context of the findings.

Prevalence of Late Effects in Childhood Cancer Survivors

Late effects are common in adults who have survived childhood cancer. Their prevalence increases as time from cancer diagnosis elapses. Multi-institutional and population-based studies have shown excess risk of hospital-related morbidity among childhood and young adult cancer survivors compared with age- and sex-matched controls, with some evidence that this risk is disproportionately high among survivors of racial and ethnic minority populations.[3,9,10,11,12,13]

Among adults who were treated for cancer during childhood, late effects contribute to a high burden of morbidity. Research has shown the following:[4,7,14,15,16,17,18]

  • 60% to more than 90% of survivors develop one or more chronic health conditions.
  • 20% to 80% of survivors experience severe or life-threatening complications during adulthood.
  • Morbidity accumulation is accelerated in young adult survivors of childhood cancer, compared with that of siblings and the general population. Accumulation of chronic diseases predicts risk of early mortality.[19]

The St. Jude Life (SJLIFE) cohort study aimed to describe the cumulative burden of cancer therapy using the cumulative burden metric, which incorporates multiple health conditions and recurrent events into a single metric that takes into account competing risks. By age 50 years, survivors in this cohort experienced an average of 17.1 chronic health conditions, 4.7 of which were severe/disabling, life threatening, or fatal.[16] This finding contrasts with the cumulative burden in matched community controls, who experienced 9.2 chronic health conditions, 2.3 of which were severe/disabling, life threatening, or fatal (see Figure 1).[16]

Charts showing distribution of cumulative burden by age among childhood cancer survivors of specific pediatric cancer subtypes and community controls participating in St. Jude Lifetime Cohort Study.
Figure 1. Figure shows distribution of cumulative burden by age among childhood cancer survivors of specific pediatric cancer subtypes and community controls participating in the SJLIFE cohort study. The cumulative burden at age 30 years and rate of cumulative burden growth is variable across cancer subtypes and organ systems. Reprinted from The Lancet, Volume 390, Issue 10112, Bhakta N, Liu Q, Ness KK, Baassiri M, Eissa H, Yeo F, Chemaitilly W, Ehrhardt MJ, Bass J, Bishop MW, Shelton K, Lu L, Huang S, Li Z, Caron E, Lanctot J, Howell C, Folse T, Joshi V, Green DM, Mulrooney DA, Armstrong GT, Krull KR, Brinkman TM, Khan RB, Srivastava DK, Hudson MM, Yasui Y, Robison LL, The cumulative burden of surviving childhood cancer: an initial report from the St Jude Lifetime Cohort Study (SJLIFE), Pages 2569–2582, Copyright (2017), with permission from Elsevier.

SJLIFE cohort study investigators compared the cumulative burden of chronic health conditions among 4,612 adolescent and young adult survivors at the ages of 18 years (the time of transition from pediatric to adult health care systems) and 26 years (the time of transition from family to individual health insurance plans) with that of 625 controls.[20]

  • Survivors at the age of 18 years experienced an average of 22.3 disabling conditions per 100 individuals versus 3.5 in controls, and 128.7 lower-severity conditions (at risk of progressing to higher-grade disabling conditions) versus 12.4 in controls.
  • Survivors at the age of 26 years experienced an average of 40.3 disabling conditions per 100 individuals versus 5.7 in controls, and 240.5 lower-severity conditions versus 51.3 in controls.
  • The cumulative burden of disabling, disease-specific conditions at the ages of 18 and 26 years was most notable for survivors of bone tumors (musculoskeletal: 99.9 and 121.70, respectively), soft tissue sarcomas (musculoskeletal: 49.5 and 54.1, respectively), and central nervous system (CNS) tumors (neurological: 24.7 and 36.8, respectively).
  • The cumulative burden of lower-severity conditions (potentially amenable to intervention) at the ages of 18 and 26 years was most notable for neurological conditions across most cancer subgroups, with the highest cumulative burden in CNS tumor survivors (95.2 and 162.3, respectively).
  • These findings highlight the importance of optimizing access to health care and health insurance as survivors age and can no longer participate in pediatric health care systems.

The variability in prevalence is related to differences in the following:

  • Age and follow-up time of the cohorts studied.
  • Methods and consistency of assessment (e.g., self-reported vs. risk-based medical evaluations).
  • Treatment intensity and treatment era.

Childhood Cancer Survivor Study (CCSS) investigators demonstrated that the elevated risk of morbidity and mortality among aging survivors in the cohort increases beyond the fourth decade of life. By age 50 years, the cumulative incidence of a self-reported severe, disabling, life-threatening, or fatal health condition was 53.6% among survivors, compared with 19.8% among a sibling control group. Among survivors who reached age 35 years without a previous severe, disabling, life-threatening, or fatal health condition, 25.9% experienced a new grade 3 to grade 5 health condition within 10 years, compared with 6.0% of healthy siblings.[4]

The presence of serious, disabling, and life-threatening chronic health conditions adversely affects the health status of aging survivors. The greatest impact is on functional impairment and activity limitations. Predictably, chronic health conditions have been reported to contribute to a higher prevalence of emotional distress symptoms in adult survivors than in population controls.[21] Female survivors demonstrate a steeper trajectory of age-dependent decline in health status than do male survivors.[22] The even-higher prevalence of late effects among cohorts evaluated by clinical assessments is related to the subclinical and undiagnosed conditions detected by screening and surveillance measures.[7]

CCSS investigators also evaluated the impact of race and ethnicity on late outcomes. The study compared late mortality, subsequent neoplasms, and chronic health conditions in Hispanic (n = 750) and non-Hispanic Black (n = 694) participants with those in non-Hispanic White participants (n = 12,397).[23] The following results were observed:

  • Cancer treatment did not account for disparities in mortality, chronic health conditions, or subsequent neoplasms observed among the groups.
  • Differences in socioeconomic status and cardiovascular risk factors affected risk. All-cause mortality was higher among non-Hispanic Black participants than among other groups, but this difference disappeared after adjustment for socioeconomic status.
  • Risk of developing diabetes was elevated among racial and ethnic minority groups even after adjustment for socioeconomic and obesity status.
  • Non-Hispanic Black patients had a higher likelihood of reporting cardiac conditions, but this risk diminished after adjusting for cardiovascular risk factors.
  • Nonmelanoma skin cancer was not reported by non-Hispanic Black participants, a finding that has been replicated by other studies.[24] Hispanic participants had a lower risk of nonmelanoma skin cancer than non-Hispanic White participants.

Recognition of late effects, concurrent with advances in cancer biology, radiological sciences, and supportive care, has resulted in a change in the prevalence and spectrum of treatment effects. In an effort to reduce and prevent late effects, contemporary therapy for most pediatric malignancies has evolved to a risk-adapted approach that is assigned on the basis of a variety of clinical, biological, and sometimes genetic factors.

The CCSS reported that with decreased cumulative dose and frequency of therapeutic radiation from 1970 to 1999, survivors have experienced a significant decrease in risk of subsequent neoplasms.[25]

  • With the exception of survivors requiring intensive multimodality therapy for refractory/relapsed malignancies, life-threatening treatment effects are relatively uncommon after contemporary therapy in early follow-up (up to 10 years after diagnosis).
  • However, survivors still frequently experience life-altering morbidity related to effects of cancer treatment on endocrine, reproductive, musculoskeletal, and neurological function.

A CCSS investigation examined temporal patterns in the cumulative incidence of severe to fatal chronic health conditions among survivors treated from 1970 to 1999.[26]

  • The 20-year cumulative incidence of at least one grade 3 to 5 chronic condition decreased significantly, from 33.2% for survivors diagnosed between 1970 and 1979, to 29.3% for those diagnosed between 1980 and 1989, to 27.5% for those diagnosed between 1990 and 1999, compared with a 4.6% incidence in a sibling cohort.
  • The overall decrease in incidence of chronic conditions across the three treatment decades was, in part, because of a substantial reduction of endocrinopathies, subsequent malignant neoplasms (SMNs), musculoskeletal conditions, and gastrointestinal conditions, whereas the cumulative incidence of hearing loss increased during this time.
  • Declines in morbidity were not uniform across the diagnosis groups or condition types because of differences in treatment and survival patterns over time. For more information, see Figure 2.
  • Despite declines in chronic health conditions over time, self-reported health status has not improved in more recent treatment eras. This finding may be because of the survival of children with higher-risk disease who would have previously died of cancer, or an enhanced awareness of and surveillance for late effects among more recently treated survivors.[27]

Graphs showing the cumulative incidence of grade 3–5 chronic health conditions in 5-year survivors of childhood cancer by diagnosis decade and siblings.
Figure 2. Cumulative incidence of grade 3–5 chronic health conditions in 5-year survivors of childhood cancer by diagnosis decade and siblings. (A) Cumulative incidence of a first grade 3–5 condition. (B) Cumulative incidence of two or more grade 3–5 conditions. The shaded area represents the 95% confidence interval (CI). The number of participants at risk (number censored) at each 5-year interval post-diagnosis is listed below the x-axis. The number censored does not include those who experienced a competing risk event (death from a cause other than a grade 5 chronic condition). Reprinted from The Lancet Oncology, Volume 19, Issue 12, Todd M Gibson, Sogol Mostoufi-Moab, Kayla L Stratton, Wendy M Leisenring, Dana Barnea, Eric J Chow, Sarah S Donaldson, Rebecca M Howell, Melissa M Hudson, Anita Mahajan, Paul C Nathan, Kirsten K Ness, Charles A Sklar, Emily S Tonorezos, Christopher B Weldon, Elizabeth M Wells, Yutaka Yasui, Gregory T Armstrong, Leslie L Robinson, Kevin C Oeffinger, Temporal patterns in the risk of chronic health conditions in survivors of childhood cancer diagnosed 1970–99: a report from the Childhood Cancer Survivor Study cohort. Pages 1590-1601, Copyright (2018), with permission from Elsevier.

Mortality

Late effects also contribute to an excess risk of premature death among long-term survivors of childhood cancer, as observed in the following studies:

  • Several studies of large cohorts of survivors have reported early mortality among individuals treated for childhood cancer, compared with age- and sex-matched general population controls. Relapsed/refractory primary cancer remains the most frequent cause of death, followed by excess cause-specific mortality from subsequent primary cancers, and cardiac and pulmonary toxicity.[28,29,30,31,32,33]
  • A CCSS study evaluated specific health-related causes of late mortality and excess deaths, compared with the general U.S. population to identify targets to reduce future risk.[33]
    • At a median follow-up of 29 years from diagnosis, the 40-year cumulative all-cause mortality rate was 23.3%, with 51.2% of deaths attributed to health-related causes.
    • Survivors who were 40 or more years from diagnosis experienced 131 excess health-related deaths per 10,000 person-years (95% confidence interval [CI], 111–163). Excess deaths were most commonly related to cancer (absolute excess risk per 10,000 person-years, 54; 95% CI, 41–68), heart disease (27; 18–38), and cerebrovascular disease (10; 5–17).
    • Healthy lifestyle (assessed by smoking status, alcohol consumption, physical activity, body mass index, and absence of hypertension and diabetes) were each associated with a 20% to 30% reduction in health-related mortality, independent of other factors.
  • An analysis of the CCSS and Surveillance, Epidemiology, and End Results (SEER) Program data evaluated conditional survival. The study demonstrated a subsequent 5-year survival rate of 92% or higher among most diagnoses at 5 years, 10 years, 15 years, and 20 years. Among those who had survived at least 5 years from diagnosis, the probability of all-cause mortality in the next 10 years was 8.8% in the CCSS and 10.6% in the SEER study, with neoplasms accounting for cause of death in approximately 75% of survivors.[34]

Despite high premature morbidity rates, overall mortality has decreased over time.[28,30,31,35,36]

CCSS investigators evaluated all-cause and health-related late mortality (including late effects of cancer therapy), SMNs, chronic health conditions, and neurocognitive outcomes among 6,148 survivors of childhood acute lymphoblastic leukemia (median age, 27.9 years; range, 5.9–61.9 years) diagnosed between 1970 and 1999.[37]

  • Overall, the 20-year all-cause late mortality rate was 6.6%.
  • Compared with participants who were treated in the 1970s, patients who were treated with risk-stratified regimens in the 1990s experienced lower health-related late mortality (rate ratio: 1990s standard risk, 0.2; 1990s high risk, 0.3), which was comparable to the U.S. population (standardized mortality ratio [SMR]: 1990s standard risk, 1.3; 1990s high risk, 1.7).

The risk of late mortality and serious chronic health conditions have decreased over time among survivors of acute myeloid leukemia (AML). CCSS investigators evaluated the long-term morbidity, mortality, and health status of more than 800 5-year survivors of childhood AML based on treatment and treatment era. Survivors were compared by treatment group (hematopoietic stem cell transplant [HSCT]); chemotherapy with cranial radiation [CRT]; chemotherapy only) and decade of diagnosis.[38]

  • Among 856 survivors, the 20-year late mortality cumulative incidence was highest after HSCT (13.9%; chemotherapy with CRT, 7.6%; chemotherapy only, 5.1%).
  • Mortality cumulative incidence decreased for survivors of HSCT diagnosed in the 1990s (8.5%) compared with the 1970s (38.9%), as did standardized mortality rates.
  • Self-reported health status was good to excellent for 88.2% of childhood AML survivors, regardless of treatment.
  • Most survivors did not experience any grade 3 to 5 chronic health conditions after 20 years (HSCT, 45.8%; chemotherapy with CRT, 23.7%; chemotherapy only, 27.0%).
  • A temporal reduction in chronic health conditions cumulative incidence was seen after HSCT (1970s, 76.1%; 1990s, 38.3%; P = .02), mirroring a reduction in total-body irradiation use.

Population-based data from a state cancer registry was used to evaluate differences in survival and long-term outcomes by race and ethnicity among 4,222 children diagnosed with cancer between 1987 and 2012.[12]

  • Compared with non-Hispanic White children, hospitalization was 70% (hazard ratio [HR], 1.7) more common 5 or more years after diagnosis for American Indian and Alaskan Native children and 50% (HR, 1.5) more common for Black children.
  • Among survivors at 5 or more years from diagnosis, 2.3-fold to 3.6-fold statistically significant relative increases were observed for hospitalizations for specific conditions for American Indian and Alaskan Native children (HR, 2.3 for infection-related conditions; HR, 3.0 for hematologic-related conditions; HR, 2.6 for digestive-related conditions). The greatest increases were noted for mental health–related conditions (HR, 3.6), a pattern also noted for Black children (HR, 2.5).

An SJLIFE cohort study explored associations between modifiable chronic health conditions and late mortality within the context of social determinants of health.[39]

  • Among 9,440 5-year childhood cancer survivors included in the analysis (median age at last follow-up, 27.5 years; median follow-up, 18.8 years), all-cause mortality (SMR, 7.6; 95% CI, 7.2–8.1) and health-related late mortality (SMR, 7.6; 95% CI, 7.0–8.2) was significantly higher than expected for U.S. mortality rates.
  • Among 3,407 adult participants who completed an on-campus assessment (median age at assessment, 35.4 years; median follow-up, 27.3 years), significant increases in late all-cause and health-related deaths were associated with the number of modifiable chronic health conditions, living in a U.S. census block associated with a high area deprivation index, and frailty.
  • Specific associations for excess health-related mortality included: one grade 2 modifiable chronic health condition (rate ratio [RR], 2.2; 95% CI, 1.1–4.4), two grade 2 modifiable chronic health conditions (RR, 2.5; 95% CI, 1.2–5.2), three grade 2 modifiable chronic health conditions (RR, 4.0; 95% CI, 1.9–8.4), area deprivation index in 51st to 80th percentile (RR, 9.2; 95% CI, 1.2–69.7), area deprivation index in 81st to 100th percentile (RR, 16.2; 95% CI, 2.1–123.7), and frailty (RR, 2.3; 95% CI, 1.2–4.1).

The CCSS and an SJLIFE cohort study investigated the contribution of cancer-predisposing variants to the risk of SMN-related late mortality (5 years or more after diagnosis).[40]

  • Among 12,469 participants (6,172 male and 6,297 female), including 4,402 from the SJLIFE cohort (median follow-up time since collection of first biospecimen, 7.4 years) and 8,067 from the CCSS cohort (median follow-up time since collection of the first biospecimen, 12.6 years), 641 (5.1%) carried cancer-predisposing variants.
  • Cancer-predisposing variants were significantly associated with an increased severity of SMNs (common terminology criteria for adverse events grade ≥4 vs. grade <4: odds ratio [OR], 2.15; 95% CI, 1.18–4.19).
  • SMN-related deaths occurred in 263 participants (2.1%), and other-cause deaths occurred in 426 survivors (3.4%).
  • At 10 years after the first biospecimen collection, the cumulative SMN-related mortality rate in carriers of cancer-predisposing variants was 3.7% (95% CI, 1.2%–8.5%) in SJLIFE and 6.9% (4.1%–10.7%) in CCSS. In comparison, the cumulative SMN-related mortality rate in noncarriers was 1.5% (1.0%–2.1%) in SJLIFE and 2.1% (1.7%–2.5%) in CCSS.
  • Carrying a cancer-predisposing variant was associated with an increased risk of SMN-related mortality (SJLIFE: HR, 3.40; 95% CI, 1.37–8.43; CCSS: HR, 3.58; 95% CI, 2.27–5.63).

Survivors of adolescent and young adult (AYA) cancers

Little information is available on late mortality among survivors of AYA cancer.[41,42,43]

  • Using SEER data, conditional relative survival up to 25 years after diagnosis was studied in a cohort of AYA patients (N = 205,954) diagnosed with a first malignant cancer (thyroid, melanoma, testicular, breast, lymphoma, leukemia, and CNS tumors).[41]
    • For all cancer types combined, among individuals who survived up to 5 years, the subsequent 5-year relative survival rate exceeded 95% by 7 years after diagnosis.
    • Most AYA cancer patients who survived at least 7 years after diagnosis experienced little difference in survival compared with the general population.
    • For specific cancer types, including CNS tumors, female breast cancer, Hodgkin lymphoma, and leukemia, evidence of excess mortality risk persisted, or re-emerged, more than 10 years after a cancer diagnosis.
    • Conditional relative survival was lowest for AYA patients with CNS tumors, although patients aged 15 to 29 years demonstrated a higher survival rate than did patients aged 30 to 39 years at the time of diagnosis of their CNS tumors.
  • A separate analysis of 5-year survivors of AYA cancer (aged 15–39 years at diagnosis), also using SEER data (N = 282,969), demonstrated the following:[42]
    • The 10-year all-cause mortality rate decreased from 8.3% for those diagnosed between 1975 and 1984 to 5.4% for those diagnosed between 2005 and 2011.
    • The decrease in mortality primarily resulted from fewer deaths from the initial cancer.
  • CCSS investigators compared chronic health conditions and all-cause and cause-specific mortality among 5,804 survivors of early-AYA cancer survivors (cancer diagnosis, age 15–20 years; median age, 42 years) and 5,804 childhood cancer survivors (cancer diagnosis, age <15 years; median age, 34 years) matched on primary cancer diagnosis.[43]
    • The SMR was 5.9 (95% CI, 5.5–6.2) for early-AYA survivors and 6.2 (95% CI, 5.8–6.6) for younger childhood cancer survivors, compared with the general population.
    • Early-AYA survivors had lower SMRs for death from health-related causes than did childhood cancer survivors (SMR, 4.8 [95% CI, 4.4–5.1] vs. 6.8 [95% CI, 6.2–7.4]), which was primarily evident more than 20 years after cancer diagnosis.
    • Early-AYA and childhood cancer survivors were at greater risk of developing severe and disabling, life-threatening, or fatal (grades 3–5) health conditions than were siblings of the same age (HR, 4.2 [95% CI, 3.7–4.8] for early-AYA and 5.6 [95% CI, 4.9–6.3] for childhood cancer survivors), although the risk was lower for early-AYA survivors than for childhood cancer survivors.
  • In a retrospective, population-based cohort study from Kaiser Permanente, cause-specific mortality in 2-year survivors (N = 10,574) of AYA cancers (patients aged 13–39 years who were diagnosed between 1990 and 2012) was examined and compared with individuals without cancer.[44]
    • AYA cancer survivors were at a 10.4-fold increased risk of death compared with the matched noncancer cohort, and this risk remained elevated at more than 20 years after diagnosis (incidence rate ratio [IRR], 2.9).
    • Beginning at 15 years after diagnosis, the incidence of second cancer–related mortality exceeded the rate of recurrence-related mortality.
    • Mortality risk of suicide was doubled in AYA cancer survivors compared with the noncancer cohort.
  • Chronic comorbidities were investigated in a retrospective, population-based cohort study of 6,778 2-year AYA cancer survivors diagnosed and monitored at Kaiser Permanente.[45]
    • Approximately 17% of the survivors developed more than one comorbidity. The most common comorbidities were dyslipidemia (22 per 1,000 person-years), hypertension (16 per 1,000 person-years), diabetes (10 per 1,000 person-years), thyroid disorders (9 per 1,000 person-years), and severe depression or anxiety (8 per 1,000 person-years).
    • IRRs were higher in survivors than in controls without a history of cancer for avascular necrosis (IRR, 8.25), followed by osteoporosis (IRR, 5.75), joint replacement (IRR, 3.89), stroke (IRR, 3.19), premature ovarian failure (IRR, 2.87), and cardiomyopathy or heart failure (IRR, 2.64).
    • For survivors of AYA cancer, the prevalence of multiple comorbidities approached 40% at 10 years after index date (a 2-year time point from diagnosis), compared with 20% for those without cancer (P < .001).

Monitoring for Late Effects

Recognition of both acute and late modality–specific toxicity has motivated investigations evaluating the pathophysiology and prognostic factors for cancer treatment–related effects. Consequently, the results of late effects research have played an important role in the following areas:

  • Changing pediatric cancer therapeutic approaches to reduce treatment-related mortality among survivors treated in more recent eras.[46]
  • The development of risk counseling and health screening recommendations for long-term survivors by identifying the clinical and treatment characteristics of those at highest risk of therapy-related complications.[47]

The common late effects of pediatric cancer encompass several broad domains, including the following:

  • Growth and development.
  • Organ function.
  • Reproductive capacity and health of offspring.
  • Secondary carcinogenesis.
  • Psychosocial sequelae related to the primary cancer, its treatment, or maladjustment associated with the cancer experience.

Late sequelae of therapy for childhood cancer can be anticipated based on therapeutic exposures, but the magnitude of risk and the manifestations in an individual patient are influenced by numerous factors. Multiple factors should be considered in the risk assessment for a given late effect (see Figure 3).[48]

Cancer-related factors:

  • Organs or tissues affected by the cancer.
  • Direct tissue effects.
  • Cancer-induced organ dysfunction or other tissue effects.

Treatment-related factors:

  • Radiation therapy: Total dose, fraction size, organ or tissue volume exposed.
  • Chemotherapy: Agent type, dose-intensity, cumulative dose, schedule.
  • Surgery: Technique, site, consequential organ dysfunction.
  • HSCT.
  • Combined-modality effects (therapeutic interactions).
  • Blood product transfusion.
  • Chronic graft-versus-host disease.

Host-related factors:

  • Sex.
  • Genetic predisposition.
  • Premorbid, comorbid, posttreatment health states and exposures.
  • Developmental status (age).
  • Time from diagnosis/therapy.
  • Inherent tissue sensitivities and capacity for normal tissue repair.
  • Hormonal milieu.
  • Socioeconomic status.
  • Health habits.

Chart showing factors influencing morbidity and mortality in the childhood cancer survivor.
Figure 3. Factors influencing morbidity and mortality of the childhood cancer survivor. Each arrow indicates a different factor affecting morbidity and mortality that exerts its effect along a continuum of care. Note that all effectors can begin exerting influence on morbidity during the period of cancer-directed therapy. Factors are separated into those that cannot be modified (red), those for which future interventions are plausible (yellow), and those for which there are known targets for interventions or areas in which therapy and surveillance have already been modified (blue). Reprinted from CA: A Cancer Journal for Clinicians, Volume 68, Issue 2, Dixon SB, Bjornard KL, Alberts NM, et al., Factors influencing risk-based care of the childhood cancer survivor in the 21st century, Pages 133–152, Copyright © 2018 American Cancer Society, with permission from John Wiley and Sons.

Resources to Support Survivor Care

Risk-based screening

The need for long-term follow-up of childhood cancer survivors is supported by the American Society of Pediatric Hematology/Oncology, the International Society of Pediatric Oncology, the American Academy of Pediatrics, the Children's Oncology Group (COG), and the Institute of Medicine. A risk-based medical follow-up is recommended, which includes a systematic plan for lifelong screening, surveillance, and prevention that incorporates risk estimates based on the following:[48]

  • Previous cancer.
  • Cancer therapy.
  • Genetic predisposition.
  • Lifestyle behaviors.
  • Comorbid conditions.
  • Sex.

Part of long-term follow-up also focuses on appropriate screening of educational and vocational progress. Specific treatments for childhood cancer, especially those that directly impact nervous system structures, may result in sensory, motor, and neurocognitive deficits that may have adverse effects on functional status, educational attainment, and future vocational opportunities. In support of this, a CCSS investigation observed the following:[49]

  • Treatment with cranial radiation doses of 25 Gy or higher was associated with higher odds of unemployment (health related: OR, 3.47; 95% CI, 2.54–4.74; seeking work: OR, 1.77; 95% CI, 1.15–2.71).
  • Unemployed survivors reported higher levels of poor physical functioning than employed survivors, had lower education and income, and were more likely to be publicly insured than unemployed siblings.

These data emphasize the importance of facilitating survivor access to individualized education services, which has been demonstrated to have a positive impact on education achievement.[50] These services may in turn enhance vocational opportunities.

In addition to risk-based screening for medical late effects, the impact of health behaviors on cancer-related health risks is also emphasized. Health-promoting behaviors are stressed for survivors of childhood cancer. Educational efforts focused on healthy lifestyle behaviors include the following:

  • Abstinence from smoking, excess alcohol use, and illicit drug use to reduce the risk of organ toxicity and, potentially, subsequent neoplasms.
  • Healthy dietary practices (e.g., a diet rich in plant foods and moderate in animal foods) [51] and active lifestyle to reduce treatment-related metabolic and cardiovascular complications.
  • Regular physical activity to reduce neurocognitive problems and enhance psychological outcomes.[52,53]
    • Survivors who engaged in consistent physical activity over time had fewer neurocognitive problems, including difficulties with task efficiency, emotional regulation, organization, and memory. They also experienced larger neurocognitive improvements, compared with those who had inconsistent activity levels.[52]
    • Vigorous exercise in survivors has been associated with a lower prevalence of depression and somatization, as well as less impairment in physical functioning, general health and vitality, emotional role limitations, and mental health quality-of-life domains.[53]

Proactively addressing unhealthy and risky behaviors is pertinent because several research investigations confirm that long-term survivors use tobacco and alcohol and have inactive lifestyles despite their increased risk of cardiac, pulmonary, and metabolic late effects.[54,55,56]

Access to risk-based survivor care

Most childhood cancer survivors do not receive recommended risk-based care. The CCSS observed the following:

  • 92.8% of survivors reported receiving some form of medical care in the previous year.[57]
  • Nearly 40% reported receiving care that focused on their previous cancer (survivor-focused care).[57]
  • Surveillance for new cases of cancer was very low in survivors at the highest risk of colon, breast, or skin cancer, suggesting that survivors and their physicians need education about the risk of subsequent neoplasms and recommended surveillance.[58]
  • Sociodemographic factors have been linked to declining rates of follow-up care over time from diagnosis. CCSS participants who were male, had a household income of less than $20,000 per year, and had lower educational attainment (high school education or less) were more likely to report no care at their most recent follow-up survey. This trend is concerning because the prevalence of chronic health conditions increases with longer elapsed time from cancer diagnosis in adults treated for cancer during childhood.[59]
  • A study that included 975 adult survivors of childhood cancer identified factors associated with attending the recommended risk-based, cancer-related medical visits. The relative risk of having a cancer-related visit was higher among survivors who:[60]
    • Assigned a greater importance to these visits.
    • Perceived a greater susceptibility to health problems.
    • Had experienced a cancer-related chronic health problem that was moderate to life-threatening.
    • Were seeing a primary care provider for a cancer-related problem.
    • Had received a cancer treatment care plan.
    • Expressed greater confidence in physicians' abilities to address questions and concerns.

Access to health insurance appears to play an important role in risk-based survivor care.[61,62] Lack of access to health insurance affects the following:

  • Cancer-related visits. In the CCSS, uninsured survivors were less likely than those privately insured to report a cancer-related visit (adjusted relative risk, 0.83; 95% CI, 0.75–0.91) or a cancer center visit (adjusted relative risk, 0.83; 95% CI, 0.71–0.98). Uninsured survivors had lower levels of utilization in all measures of care than privately insured survivors. In contrast, publicly insured survivors were more likely to report a cancer-related visit (adjusted relative risk, 1.22; 95% CI, 1.11–1.35) or a cancer center visit (adjusted relative risk, 1.41; 95% CI, 1.18–1.70) than were privately insured survivors.[61]
  • Health care outcomes. In a study comparing health care outcomes for long-term AYA cancer survivors with young adults who have no cancer history, the proportion of uninsured survivors did not differ between the two groups.[63]
  • Financial burden. Subgroups of adult survivors of childhood cancer may be at additional risk of health care barriers due to financial hardship. Younger survivors (aged 20–29 years), females, non-White survivors, and survivors reporting poorer health faced more cost barriers, which may inhibit the early detection of late effects.[63] Survivors are more likely than their siblings to forego needed medical care related to financial challenges.[64]

Overall, lack of health insurance—related to health issues, unemployment, and other societal factors—remains a significant concern for survivors of childhood cancer.[65,66] Legislation, including the Health Insurance Portability and Accountability Act (HIPAA),[67,68] has improved access and retention of health insurance among survivors, although the quality and limitations associated with these policies have not been well studied.

Transition to Survivor Care

Long-term follow-up programs

Transition of care from the pediatric to adult health care setting is necessary for most childhood cancer survivors in the United States.

When available, multidisciplinary long-term follow-up programs in the pediatric cancer center work collaboratively with community physicians to provide care for childhood cancer survivors. This type of shared care has been proposed as the optimal model to facilitate coordination between the cancer center oncology team and community physician groups providing survivor care.[69]

An essential service of long-term follow-up programs is the organization of an individualized survivorship care plan that includes the following:

  • Details about therapeutic interventions undertaken for childhood cancer and their potential health risks (e.g., chemotherapy type and cumulative dose, radiation treatment fields and dose, surgical procedures, blood product transfusions, and HSCT).
  • Personalized health screening recommendations.
  • Information about lifestyle factors that modify risks.

A CCSS investigation that evaluated perceptions of future health and cancer risk highlighted the importance of continuing education of survivors during long-term follow-up evaluations. A substantial subgroup of adult survivors reported a lack of concern about future health (24%) and subsequent cancer risks (35%), even after exposure to treatments associated with increased risks. These findings present concerns that survivors may be less likely to engage in beneficial screenings and risk-reduction activities.[70]

The CCSS evaluated the surveillance and screening practices of 11,337 childhood cancer survivors. They found that fewer than half of high-risk survivors at increased risk of developing SMNs or cardiac dysfunction received the recommended surveillance, which likely exposes them to preventable morbidity and mortality.[58]

  • 27% of survivors and 20% of primary care providers (PCP) had a survivorship care plan. Survivors treated after 1990 were more likely to have a survivorship care plan.
  • Survivorship care plan possession by high-risk survivors was associated with increased adherence to COG-recommended breast (22% vs. 8%), skin (35% vs. 23%), and cardiac (67% vs. 33%) surveillance. PCP survivorship care plan possession was associated with increased adherence to skin surveillance (40% vs. 23%).
  • Among high-risk survivors, adherence increased for colorectal (14% to 41%, P < .001) and cardiac (22% to 38%, P < .001) surveillance and decreased for breast surveillance (38% to 13%, P < .001) between 2007 and 2016.
  • For average-risk survivors, better adherence to American Cancer Society recommendations for breast (57%), cervical (84%), and colorectal (69%) screening was observed than with COG recommendations. PCP survivorship care plan possession was associated with increased adherence to breast and colorectal screening. Survivors were less adherent to breast screening than the general population and less adherent to cervical screening than siblings.

For survivors who have not been provided with this information, the COG offers a template that can be used by survivors to organize a personal treatment summary. For more information, see the COG Survivorship Guidelines, Appendix 1.

COG long-term follow-up guidelines for childhood and AYA cancer survivors

To facilitate survivor and provider access to succinct information to guide risk-based care, COG investigators have organized a compendium of exposure- and risk-based health surveillance recommendations, with the goal of standardizing the care of childhood cancer survivors.[71]

The compendium of resources includes the following:

Information concerning late effects is summarized in tables throughout this summary.

Several groups have undertaken research to evaluate the yield from risk-based screening as recommended by the COG and other pediatric oncology cooperative groups.[7,73,74] Pertinent considerations in interpreting the results of these studies include the following:

  • Variability in the cohort's age at treatment.
  • Age at screening.
  • Time from cancer treatment.
  • Participation bias.

Collectively, these studies demonstrate that screening identifies a substantial proportion of individuals with previously unrecognized, treatment-related health complications of varying degrees of severity. Study results have also identified low-yield evaluations that have encouraged revisions of screening recommendations. Ongoing research is evaluating the cost effectiveness of screening in the context of consideration of benefits, risks, and harms.

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Subsequent Neoplasms

Subsequent neoplasms (SNs) are defined as histologically distinct neoplasms developing at least 2 months after completion of treatment for the primary malignancy. SNs may be benign or malignant. Childhood cancer survivors have increased risks of developing SNs that are multifactorial in etiology and vary according to the following:

  • Host factors (e.g., genetics, immune function, hormone status).
  • Primary cancer therapy.
  • Environmental exposures.
  • Lifestyle factors.

SNs are the leading cause of nonrelapse late mortality (standardized mortality ratio, 15.2; 95% confidence interval [CI], 13.9–16.6).[1] The Childhood Cancer Survivor Study (CCSS) reported the following 30-year cumulative incidence rates:[2]

  • All SNs: 20.5% (95% CI, 19.1%–21.8%).
  • Nonmelanoma skin cancer (NMSC): 9.1% (95% CI, 8.1%–10.1%).
  • SNs with malignant histologies (excluding NMSC): 7.9% (95% CI, 7.2%–8.5%).
  • Meningioma: 3.1% (95% CI, 2.5%–3.8%).

This represents a sixfold increased risk of SNs among cancer survivors, compared with the general population.[2]

Several studies have described the excess risk of SNs.[3,4]

Evidence (excess risk of SNs):

  1. A population-based study that leveraged registry data evaluated early second primary tumors occurring within 5 years of a first primary cancer diagnosed before age 15 years (1971–2010).[5]
    • Early second primary tumors developed in 0.4% of cancer survivors, which is a sevenfold excess risk (standardized incidence ratio [SIR], 7.7; 95% CI, 6.7–8.9).
    • Excess risk was higher among children diagnosed between 1981 and 1990 (SIR, 9.5; 95% CI, 7.1–12.5), compared with earlier or later decades (SIR, 6.5–7.5).
    • Cancer predisposition syndromes were implicated in 21% of children with early second primary tumors and suspected in another 5%.
  2. An international case-control study pooled data for an analysis of meningioma risk after treatment for childhood cancer. The study evaluated the magnitude of radiation dose–response association, potential modifiers of radiation risks, and the role of chemotherapy.[6]
    • Increasing radiation dose was associated with increased risk of meningioma (excess odds ratio [OR]/Gy, 1.44; 95% CI, 0.6–3.6), without evidence of departure from linearity.
    • Exposure to radiation doses of 24 Gy or higher was associated with more than 30-fold higher odds of developing a meningioma (OR, 33.7; 95% CI, 14.1–80.3).
    • Patients aged 10 years or older at treatment had a significantly lower radiation dose–response association compared with those treated before the age of 10 years (excess OR/Gy, 0.57; 95% CI, 0.18–1.91 vs. 2.20; 95% CI, 0.87–6.31).
    • Treatment with methotrexate was associated with an increased risk of meningioma (OR, 3.43; 95% CI, 1.56–7.57), but without evidence of a dose-response association or interaction with radiation dose.
    • Meningioma risk associated with radiation exposure remained significantly elevated 30 years after treatment (excess OR/Gy, 3.76; 95% CI, 0.77–29.15).
  3. A CCSS cohort reported on any new SN (including malignant neoplasms, NMSCs, benign meningiomas, and other benign neoplasms) occurring after age 40 years.[3]
    • At the age of 55 years, the cumulative incidence of any new SN was 34.6%. The incidence of malignant SNs was 16.3%.
    • Female sex and therapeutic radiation exposure were associated with an increased risk of developing SNs in multivariate analysis.

    Prolonged follow-up has established that multiple SNs are common among aging childhood cancer survivors.[7,8]

  4. The CCSS also reported the following:[4]
    • Individuals treated in more recent treatment eras experienced decreased risk of SNs (including subsequent malignancies, NMSCs, and benign meningiomas) compared with those treated earlier. This lower risk was attributed to decreased exposure to therapeutic radiation.
    • However, individuals treated in the 1990s remain at increased risk of SNs compared with the general population.
  5. CCSS investigators evaluated morbidity and mortality associated with meningioma among 4,221 participants treated with cranial radiation therapy.[9]
    • The cumulative incidence of subsequent meningioma by age 40 years was 5.6% in this group of patients, and the incidence was without demonstrable plateau.
    • Risk factors for subsequent meningioma included female sex (hazard ratio [HR], 1.7; 95% CI, 1.2–2.3) and higher cranial radiation dose (HR, 2.6; 95% CI, 1.6–4.2 after 30 Gy or higher).
    • Among survivors reporting meningiomas, the risk of neurological sequelae occurring 5 or more years after primary cancer diagnosis was increased for seizures (HR, 10.0; 95% CI, 7.0–15.3); auditory-vestibular-visual sensory deficits (HR, 2.3; 95% CI, 1.3–4.0); focal neurological dysfunction (HR, 4.9; 95% CI, 3.2–7.5); and severe headaches (HR, 3.2; 95% CI, 1.9–5.4).
    • With a median follow-up of 72 months after meningioma diagnosis, 13% of the patients had died, with six deaths attributed to meningioma.
  6. Dutch Childhood Oncology Group (DCOG)–LATER investigators evaluated the cumulative meningioma incidence and performed excess relative risk modeling of benign meningiomas in childhood cancer patients.[10]
    • Among 5,843 childhood cancer survivors (median follow-up, 23.3 years; range, 5.0–52.2 years), 97 patients developed a benign meningioma, including 80 after full-volume cranial radiation and 14 after partial-volume cranial radiation.
    • The 40-year cumulative incidence of meningioma after any cranial radiation was 12.4% (95% CI, 9.8%–15.2%).
    • Compared with cranial radiation doses of 1 to 19 Gy, no cranial radiation was associated with a low meningioma risk (HR, 0.04; 95% CI, 0.01–0.15), while increased risks were observed for doses of 20 to 39 Gy (HR, 1.66; 95% CI, 0.83–3.33) and 40 Gy or higher (HR, 2.81; 95% CI, 1.30–6.08).
    • Survivors diagnosed before the age of 5 years showed significantly increased risks (HR, 2.38; 95% CI, 1.39–4.07) compared with patients diagnosed between the ages of 10 and 17 years.
    • Radiation volume was not significantly associated with increased risk (HR for full vs. partial volume, 1.66; 95% CI, 0.86–3.22) and dose effects did not vary significantly according to exposure age or radiation volume.
    • Treatment with carboplatin was associated with meningioma risk (HR, 3.55; 95% CI, 1.62–7.78), but a dose-response was not observed, and all nine exposed cases had received high-dose cranial radiation.
    • In a follow-up study from the DCOG-LATER cohort, 90% of survivors with meningioma presented with symptoms rather than through late effects clinic screening, and 32% of survivors presented with synchronous meningiomas.[11]
  7. CCSS investigators have also evaluated associations between chemotherapy and subsequent malignant neoplasms (SMNs) among nonirradiated, long-term survivors.[12]
    • Of 1,498 SMNs in 1,344 survivors, 229 occurred in 206 survivors who were treated with chemotherapy only.
    • The 30-year SMN cumulative incidence was 3.9% for the chemotherapy-only group, 9.0% for the chemotherapy-plus-radiation group, 10.8% for the radiation-only group, and 3.4% for the neither-treatment group.
    • SIRs for SMNs were increased for any SMN (SIR, 2.8), subsequent leukemia/lymphoma (SIR, 1.9), breast cancer (SIR, 4.6), soft tissue sarcoma (SIR, 3.4), thyroid cancer (SIR, 3.8), and melanoma (SIR, 2.3).
    • The SMN rate was significantly associated with exposure to platinum chemotherapy doses higher than 750 mg/m2 (relative rate, 2.7) and alkylating agents (relative rate, 1.2 per 5,000 mg/m2).
    • The breast cancer rate showed a linear dose response (relative rate, 1.3 per 100 mg/m2) with anthracycline exposure.
  8. DCOG-LATER investigators evaluated the contribution of chemotherapy to solid cancer risk in a large cohort of childhood cancer survivors diagnosed between 1963 and 2001 (median follow-up, 20.7 years).[13]
    • The 25-year cumulative SN incidence was 3.9% and did not change across decades.
    • Survivors treated with doxorubicin exhibited a dose-dependent increased risk of all solid cancers and breast cancer. This relationship was stronger in survivors with Li-Fraumeni syndrome–associated childhood cancers (leukemia, central nervous system [CNS], and sarcomas other than Ewing) than in survivors of other cancers.
    • Among female survivors who did not receive chest radiation or total-body irradiation (TBI) and developed breast cancer (n = 31), HRs for doxorubicin dose tertiles were 1.3 (95% CI, 0.3–6.1), 5.6 (95% CI, 1.9–16.2), and 9.9 (95% CI, 4.2–23.8).
    • A dose-response relationship was confirmed with cyclophosphamide and subsequent sarcoma, particularly bone sarcoma. The HR for subsequent sarcoma was 3.1 (95% CI, 1.5–6.0) for survivors who received cyclophosphamide at a dose greater than 9,400 mg/m2 and 2.6 (95% CI, 1.3–5.2) for those who received ifosfamide.
  9. St. Jude Life (SJLIFE) cohort study investigators assessed the contribution of pathogenic and likely pathogenic variants in cancer predisposition genes to SN risk in childhood cancer survivors.[14]
    • Of 3,006 study participants evaluated by whole-genome sequencing (30-fold), 1,120 SNs were diagnosed among 439 survivors (14.6%), and 175 pathogenic or likely pathogenic variants were identified in 5.8% of survivors. The prevalence of a pathogenic or likely pathogenic variant among nonirradiated survivors with SNs was much higher, at 18%.
    • Variants were associated with significantly increased rates of breast cancer (relative risk [RR], 13.9) and sarcoma (RR, 10.6) among irradiated survivors and with developing any SN (RR, 4.7), breast cancer (RR, 7.7), nonmelanoma skin cancer (RR, 11), and two or more histologically distinct SNs (RR, 18.6).
    • Variant carriers did not have an increased rate of meningioma or thyroid cancer.

The incidence and type of SNs depend on the following:

  • Primary cancer diagnosis.
  • Type of therapy received.
  • Presence of genetic conditions.

Unique associations with specific therapeutic exposures have resulted in the classification of SNs into the following two distinct groups:

  • Myelodysplastic syndrome postcytotoxic therapy (MDS-pCT) and acute myeloid leukemia postcytotoxic therapy (AML-pCT) (previously termed t-MDS and t-AML).
  • Therapy-related solid SNs.

Myelodysplastic Syndrome and Acute Myeloid Leukemia Postcytotoxic Therapy (MDS-pCT and AML-pCT)

Subsequent primary leukemias have been reported in survivors of Hodgkin lymphoma, leukemia, sarcoma, CNS tumors, non-Hodgkin lymphoma, neuroblastoma, and Wilms tumor. In a cohort of nearly 70,000 5-year childhood cancer survivors, survivors had a fourfold increased risk (SIR, 3.7) of developing a leukemia, with an absolute excess risk of 7.5. Specifically, a sixfold relative risk of developing a myeloid leukemia (SIR, 5.8) was reported.[15]

  • The risk remained significantly elevated beyond 20 years from the first primary malignancy (SIR, 2.4).
  • Hodgkin lymphoma survivors had the greatest excess risk of developing a subsequent leukemia (SIR, 7.9) and specifically a myeloid leukemia (SIR, 12.1), with the largest excess risk seen before 20 years of follow-up.

A pooled analysis examined all published studies with detailed treatment data for children with cancer diagnosed between 1930 and 2000. Treatment data included estimated radiation doses to the active bone marrow and doses of specific chemotherapy agents. In this report, 147 cases of second primary leukemia (69% of cases were AML) were matched to 522 controls.[16]

  • After controlling for other therapies, topoisomerase II inhibitor therapy was associated with an increased risk of second AML (no radiation and >2,500 mg/m2 vs. none: OR, 14.3; 95% CI, 2.7–75.1).
  • Radiation dose to the active bone marrow was also associated with an increased risk of second AML among patients who did not receive chemotherapy (>0–12 Gy: OR, 4.9; 95% CI, 0.95–25.6) but not among those who received chemotherapy.
  • Second primary leukemias were most likely to occur in the first decade after cancer treatment.

Characteristics of MDS-pCT and AML-pCT include the following:[17,18]

  • A short latency (<10 years from primary cancer diagnosis). The risk of MDS-pCT or AML-pCT plateaus after 10 to 15 years. Although the risk of subsequent leukemia remains significantly elevated beyond 15 years from primary diagnosis (SIR, 3.5; 95% CI, 1.9–6.0), these events are relatively rare, with an absolute excess risk of 0.02 cases per 1,000 person-years.[18]
  • An association with alkylating agents and/or topoisomerase II inhibitors.

Based on the updated definitions from the World Health Organization, MDS-pCT and AML-pCT are clonal disorders, which arise in patients previously exposed to cytotoxic therapy, either chemotherapy or large-field radiation therapy, for an unrelated neoplasm.[19] The following two types of MDS-pCT and AML-pCT are the most frequently observed among survivors:

  • Alkylating agent–related type: Alkylating agents associated with MDS-pCT and AML-pCT include cyclophosphamide, ifosfamide, mechlorethamine, melphalan, busulfan, nitrosoureas, chlorambucil, and dacarbazine.[20]

    The risk of alkylating agent–related MDS or AML is dose dependent, with a latency of 3 to 5 years after exposure; it is associated with abnormalities involving chromosomes 5 (-5/del(5q)) and 7 (-7/del(7q)).[20]

  • Topoisomerase II inhibitor–related type: Topoisomerase II inhibitor agents include etoposide, teniposide, and anthracycline-related drugs.

    Most of the translocations observed in patients exposed to topoisomerase II inhibitors disrupt a breakpoint cluster region between exons 5 and 11 of the band 11q23 and fuse KMT2A with a partner gene.[20] Topoisomerase II inhibitor–related AML presents as overt leukemia after a latency of 6 months to 3 years and is associated with balanced translocations involving chromosome bands 11q23 or 21q22.[21]

For more information, see the Therapy-Related AML and Therapy-Related Myelodysplastic Neoplasms section in Childhood Acute Myeloid Leukemia Treatment.

Therapy-Related Solid SNs

Therapy-related solid SNs represent 80% of all SNs, demonstrate a strong relationship with radiation exposure, and are characterized by a latency that exceeds 10 years. The risk of solid SNs continues to increase with longer follow-up. The risk of solid SNs is highest when the following occur:[4,13]

  • Younger age at time of radiation exposure.
  • High total dose of radiation.
  • Longer period of follow-up after radiation exposure.

The histological subtypes of solid SNs encompass a neoplastic spectrum ranging from benign and low-grade malignant lesions (e.g., NMSC, meningiomas) to high-grade malignancies (e.g., breast cancers, glioblastomas) (see Figure 4).[4,13,22,23]

Graph showing fitted radiation dose (Gy) response by type of second cancer: sarcoma, skin cancer (BCC), meningioma, salivary gland cancer, glioma, breast cancer, and thyroid cancer.
Figure 4. Fitted radiation dose-response by type of second cancer, based on previously published studies of second sarcoma, skin, meningioma, salivary gland, glioma, breast, and thyroid gland. The order of second cancers from top to bottom in the graph is the same as in the key to the right of the panel. Reprinted from International Journal of Radiation Oncology*Biology*Physics, Volume 94, Issue 4, Inskip PD, Sigurdson AJ, Veiga L, et al., Radiation-Related New Primary Solid Cancers in the Childhood Cancer Survivor Study: Comparative Radiation Dose Response and Modification of Treatment Effects, Pages 800–807, Copyright © 2016, with permission from Elsevier.

Solid SNs in childhood cancer survivors most commonly involve the following:[4,13,22,24,25,26,27]

  • Breast.
  • Thyroid.
  • CNS.
  • Bone and soft tissue.
  • Skin.

With longer follow-up of adult survivors of childhood cancer cohorts, epithelial neoplasms have been observed in the following:[13,28]

  • Lung.
  • Gastrointestinal tract.
  • Oral cavity.
  • Genitourinary system.
  • Kidney.

Benign and low-grade SNs, including NMSCs and meningiomas, have also been observed with increasing prevalence in survivors who were treated with radiation therapy for childhood cancer.[4,10,29]

Subsequent neoplasms after hematopoietic stem cell transplant (HSCT)

Recipients of HSCT are treated with high-dose chemotherapy and, often, TBI, which makes their risk of SNs unique from that of the general oncology population.

  • Among 4,318 first-time allogeneic HSCT recipients treated for AML and chronic myeloid leukemia between 1986 and 2005, and conditioned with high-dose busulfan and cyclophosphamide (Bu-Cy), 66 solid cancers were reported at a median of 6 years post-HSCT.[30]
    • The cumulative incidence of new solid cancers was 0.9% at 5 years and 2.4% at 10 years and appears to be similar, regardless of exposure to radiation.
    • Bu-Cy conditioning without TBI was associated with higher risks of solid SNs than in the general population.
    • Chronic graft-versus-host disease increased the risk of SNs, especially those involving the oral cavity.
  • A study of 4,905 1-year survivors of allogeneic HSCT who underwent transplant between 1969 and 2014 for malignant or nonmalignant diseases, and were followed for a median 12.5 years, demonstrated a strong effect of TBI dose and dose fractionation on risk of SNs.[31]
    • The 20-year cumulative incidence of SN after HSCT for individuals treated at younger than 20 years was 8.1%.
    • SN risk was highest in survivors exposed to high-dose, single-fraction TBI (6–12 Gy) or very high-dose fractionated TBI (14.4–17.5 Gy).
    • With low-dose TBI (2–4.5 Gy), the SN risk was comparable to the risk with chemotherapy alone, although it was still twofold higher than in the general population.
    • Among individuals treated at younger than 20 years, the number of SNs was 12.5-fold higher than expected in the general population, and the excess absolute risk was 10.6 per 1,000 person-years. Survivors treated with HSCT at this young age were more likely to develop SNs than were survivors who were treated after age 50 years (HR, 2.3).

Some well-established solid SNs are described in the following sections.

Breast cancer

Female survivors of childhood, adolescent, and young adult cancer treated with radiation therapy to fields including the chest are at increased risk of developing breast cancer.

  • The cumulative breast cancer incidence ranges from 8% to 20% by age 40 to 45 years among childhood cancer survivors and is as high as 35% by age 50 years in Hodgkin lymphoma survivors, comparable to that observed among BRCA gene variant carriers.[17,32,33,34,35]
  • Radiation dose and volume of breast exposed are important factors affecting risk. Specific chemotherapeutic agents, particularly alkylating agents and anthracyclines, may affect risk as well.[32,34,36]

Evidence (excess risk of breast cancer):

  1. Breast cancer is the most common therapy-related solid SN after a previous diagnosis of Hodgkin lymphoma.[17,33] The following has been observed in female survivors of childhood Hodgkin lymphoma:
    • Excess risk of breast cancer has been reported in survivors treated with high-dose, extended-volume radiation at age 30 years or younger.[37]
    • Data indicate that females treated with low-dose, involved-field radiation also exhibit excess breast cancer risk.[38]
    • Patients who received limited volume supradiaphragmatic radiation therapy (excluding the axillae) had a significantly lower risk of subsequent breast cancers than patients who received full mantle-field radiation therapy.[36]
    • For patients treated with radiation therapy to the chest before age 16 years, the cumulative incidence of breast cancer approaches 20% by age 45 years.[17]
    • The latency period after chest irradiation ranges from 8 to 10 years, and the risk of subsequent breast cancer increases in a linear fashion with radiation dose (P for trend < .001).[39]
    • Treatment with higher cumulative doses of alkylating agents and ovarian radiation of 5 Gy or higher (exposures predisposing to premature menopause) have been correlated with reductions in breast cancer risk, underscoring the potential contribution of hormonal stimulation on breast carcinogenesis.[36,40,41]
    • The observed number of invasive breast cancer cases among young (aged <30 years) survivors, compared with what is expected in the general population, has decreased over recent treatment eras (1970s SIR, 55.0 vs. 1990s SIR, 14.3).[35]
  2. The risk of breast cancer was also increased in the following studies that used lower radiation doses to treat cancer that metastasized to the chest/lung (e.g., Wilms tumor, sarcoma) and exposed the breast tissue:
    1. In 116 children in the CCSS cohort treated with 2 Gy to 20 Gy to the lungs (median, 14 Gy), the SIR for breast cancer was 43.6 (95% CI, 27.1–70.1).[34]
    2. A report of 2,492 female participants in the National Wilms Tumor Studies 1 through 4 (1969–1995) addressed the excess risk of breast cancer.[42]
      • Sixteen of 369 women who received chest irradiation for metastatic Wilms tumor developed invasive breast cancer (cumulative risk at age 40 years, 14.8% [95% CI, 8.7%–24.5%]). The SIR of 27.6 (95% CI, 16.1–44.2) was based on 5,010 person-years of follow-up.
      • Of the 369 patients, radiation doses to the chest were less than 12 Gy in 4%, 12 Gy in 64%, 13 Gy to 15 Gy in 19%, and more than 15 Gy in 13% of patients.
      • For all patients who developed breast cancer (with or without chest irradiation), the median age at first breast cancer diagnosis was 34.3 years (range, 15.5–48.4) and the median time from Wilms tumor diagnosis was 27.1 years (range, 7.9–35.7).
  3. An international collaborative study pooled individual patient data from 17,903 childhood cancer survivors. The study evaluated the dose-dependent effects of individual anthracycline agents on the development of subsequent breast cancer and interactions with chest radiation therapy. There were 782 survivors (4.4%) who developed a subsequent breast cancer.[43]
    • Doxorubicin was associated with a dose-dependent increase of subsequent breast cancer risk (HR per 100 mg/m2, 1.24; 95% CI, 1.18–1.31).
    • There was a more-than-twofold increased risk for survivors treated with 200 mg/m2 or higher cumulative doxorubicin dose, compared with no doxorubicin (HR, 2.50 for 200–299 mg/m2; HR, 2.33 for 300–399 mg/m2; HR, 2.78 for ≥400 mg/m2).
    • The associations were not statistically significant for daunorubicin, whereas epirubicin was associated with increased subsequent breast cancer risk (exposure yes vs. no: HR, 3.25; 95% CI, 1.59–6.63).
    • The HRs per 100 mg/m2 of doxorubicin were 1.11 (95% CI, 1.02–1.21) for patients treated with chest radiation therapy and 1.26 (95% CI, 1.17–1.36) for patients who did not receive chest radiation therapy.
  4. The risk of developing breast cancer after radiation therapy and chemotherapy with anthracyclines was evaluated in the CCSS. In a nested-case control study of 271 childhood cancer survivors (diagnosed between 1970–1986) who were subsequently diagnosed with breast cancer, the combination of anthracyclines and radiation therapy to the breast was associated with increased risks of breast cancer consistent with an additive interaction.[32]
    • For the study group, the median age of first cancer diagnosis was 15 years and the median age at breast cancer diagnosis was 39 years.
    • The OR for breast cancer increased with increasing radiation dose to the breast (OR per 10 Gy, 3.9; 95% CI, 2.5–6.5) and was similar for estrogen receptor–positive and estrogen receptor–negative cancers.
    • The OR per 10 Gy to the breast was higher for women who received ovarian doses less than 1 Gy (OR, 6.8; 95% CI, 3.9–12.5) than for women who received ovarian doses greater than or equal to 15 Gy (OR, 1.4; 95% CI, 1.0–6.4).
    • The OR for breast cancer increased with cumulative anthracycline dose (OR per 100 mg/m2, 1.23; 95% CI, 1.09–1.39; P < .01 for trend).
    • There was an additive interaction between radiation therapy and anthracycline treatment. The OR was 19.1 (95% CI, 7.6–48.0) for the combined association of anthracycline therapy and breast radiation dose of 10 Gy or more (compared with 0 to less than 1 Gy) versus 9.6 (95% CI, 4.4–20.7) without anthracycline therapy.
  5. Childhood cancer survivors not exposed to chest radiation also have an increased risk of breast cancer at a young age.
    1. The SJLIFE study assessed subsequent breast cancer risk among 1,467 female cancer survivors and evaluated risk associated with anthracycline exposure. The study also evaluated whether surveillance imaging affects breast cancer outcomes.[24]
      • In women who received neither chest radiation nor anthracyclines, the cumulative incidence of breast cancer was 2% at age 35 years and 15% at age 50 years. For women who were treated with 250 mg/m2 or higher of anthracyclines, the rates were 7% at age 35 years and 46% at age 50 years.
      • Anthracycline doses of 250 mg/m2 or higher remained significantly associated with increased risk of breast cancer in models, excluding survivors with cancer predisposition gene variants, chest radiation of 10 Gy or higher, or both.
      • Breast cancers detected by imaging and/or prophylactic mastectomy were more likely to be in situ carcinomas, be smaller masses, have no lymph node involvement, and be treated without chemotherapy, compared with breast cancers detected by physical findings.
      • Dual imaging with mammography and breast magnetic resonance imaging (MRI) in this cohort was a sensitive and specific approach to identify breast cancers that require less aggressive therapy than breast cancers detected by physical findings.
    2. A CCSS investigation examined the breast cancer risk of 3,768 female participants who did not receive chest radiation.[44]
      • A fourfold excess risk (SIR, 4.0; 95% CI, 3.0–5.3) of breast cancer was observed compared with rates in the general population.
      • Breast cancer risk was highest among survivors of sarcoma (SIR, 5.3; 95% CI, 3.6–7.8) and leukemia (SIR, 4.1; 95% CI, 2.4–6.9), for whom the cumulative incidence of breast cancer was estimated to be 5.8% and 6.3%, respectively, by age 45 years.
      • Treatment with alkylating agents and anthracyclines increased the risk of breast cancer in a dose-dependent manner.
    3. CCSS investigators also examined SN risk among 7,448 participants who were treated with chemotherapy only.[12]
      • Breast cancer incidence was 4.6-fold greater than what would be expected in the general population (SIR, 4.6; 95% CI, 3.5–6.0).
      • A linear dose response was demonstrated between anthracyclines and breast cancer rate (RR, 1.3/100 mg/m2; 95% CI, 1.2–1.6).
    4. DCOG-LATER investigators evaluated the contribution of chemotherapy to solid cancer risk in a large cohort of childhood cancer survivors diagnosed between 1963 and 2001.[13]
      • Survivors treated with doxorubicin exhibited a dose-dependent increased risk of breast cancer (HR, 3.1; 95% CI, 1.4–6.5 among survivors treated with anthracycline doses of 250 mg/m2 or higher).
      • The doxorubicin–breast cancer dose response was stronger for survivors of Li-Fraumeni–associated cancers (leukemia, CNS, and sarcomas other than Ewing) than for survivors of other cancers.
  6. A SEER Program–based study evaluated trends in surgical management and the 5- and 10-year cumulative incidence of contralateral breast cancer among women who were treated with radiation therapy for Hodgkin lymphoma before age 30 years and diagnosed with a subsequent breast cancer between 1990 and 2016.[45]
    • Overall, 263 (89.2%) women presented with unilateral breast cancer, 50 of whom (19.0%) underwent breast-conserving surgery and 213 of whom (81.0%) underwent mastectomy (40.5% bilateral).
    • The 5-year incidence of contralateral breast cancer in women who underwent unilateral surgery was 9.4% (95% CI, 5.6%–15.4%), increasing to 20.2% (95% CI, 13.7%–29.2%) at 10 years and 29.9% (95% CI, 20.8%–41.9%) at 15 years. This finding underscores the importance of ongoing breast cancer surveillance and consideration of prophylactic mastectomy.

Breast cancer risk varies among childhood cancer survivors who are treated with chest radiation therapy, and the risk is based on multiple clinical factors. The first personalized breast cancer risk prediction model was developed and validated using multinational cohorts of female 5-year cancer survivors who were diagnosed at younger than 21 years and treated with chest irradiation (n = 2,147). The model includes current age, chest radiation field, whether chest radiation was delivered within 1 year of menarche, anthracycline exposure, age of menopause, and history of a first-degree relative with breast cancer. The model is available as an online risk calculator.[46]

Subsequent versus de novo breast cancer

Several studies have investigated the clinical characteristics of subsequent breast cancers arising in women treated with radiation therapy for childhood cancer.[47,48,49,50,51]

  • In one population-based study, radiation-induced breast cancer was noted to have more adverse clinicopathological features, as evidenced by a twofold increased risk of estrogen receptor–negative, progesterone receptor–negative breast cancer observed among 15-year Hodgkin lymphoma survivors, compared with women who had sporadic breast cancer.[47]
  • Other studies have observed a higher proportion of more histologically aggressive subtypes (e.g., triple-negative breast cancer) than age-matched sporadic invasive cancers.[48,49]
  • These findings are in contrast to other smaller, hospital-based, case-control studies of breast cancer among Hodgkin lymphoma survivors that have not identified a significant variation in hormone receptor status when compared with primary breast cancer controls. Previous studies have also not demonstrated a significant difference in overall risk of high-grade versus low-grade tumors.[50,51]
  • A study using SEER Program data evaluated the clinicopathological features of 321 breast cancers diagnosed in 257 women (median age, 22 years; range, 18–26 years at Hodgkin lymphoma diagnosis) who were previously treated with radiation for Hodgkin lymphoma.[52]
    • Women who developed breast cancer after radiation for Hodgkin lymphoma were younger than women diagnosed with breast cancer without a prior malignancy (43 vs. 60 years) and were less likely to present with ductal carcinoma in situ (0.4% vs. 14.9%).
    • Radiation was not associated with poorer biological features, compared with breast cancers diagnosed in similarly aged women with no prior malignancy. However, higher proportions of upper outer quadrant and smaller tumors (≤2 cm) were found.
    • Most tumors in survivors of Hodgkin lymphoma were hormone sensitive (nearly two-thirds were estrogen receptor–positive/HER2-negative). This finding suggests that endocrine prevention may be an option for this high-risk population.

Mortality after subsequent breast cancer

In a study of female participants in the CCSS who were subsequently diagnosed with breast cancer (n = 274) and matched to a control group of women (n = 1,095) with de novo breast cancer, the following was observed:[53]

  • Survivors of childhood cancer were found to have elevated mortality rates (HR, 2.2; 95% CI, 1.7–3.0), even after adjusting for breast cancer treatment.
  • Survivors were five times more likely to die from other health-related causes, including other SMNs and cardiovascular or pulmonary disease (HR, 5.5; 95% CI, 3.4–9.0).
  • The cumulative incidence of a second asynchronous breast cancer was elevated significantly compared with controls (at 5 years, 8.0% among childhood cancer survivors vs. 2.7% among controls; P < .001).

Although current evidence does not show a survival benefit from the initiation of breast cancer surveillance in women treated with radiation therapy to the chest for childhood cancer, interventions to promote detection of small and early-stage tumors may improve prognosis. Those with more limited treatment options because of previous exposure to radiation or anthracyclines may especially benefit.

In support of surveillance, SJLIFE investigators observed that breast cancers detected by imaging and/or prophylactic mastectomy were more likely to be in situ carcinomas, be smaller masses (3.3 cm mean tumor size detected by physical examination vs. 1.1 cm detected by imaging), have no lymph node involvement, and be treated without chemotherapy, compared with breast cancers detected by physical findings.[24]

Investigators used data from the CCSS and two Cancer Intervention and Surveillance Modeling Network breast cancer simulation models to estimate the clinical benefits, harms, and cost-effectiveness of breast cancer screening among childhood cancer survivors who were previously treated with chest radiation.[54]

  • Screening with mammography and MRI, as recommended in COG Long-Term Follow-Up guidelines, is projected to avert half of the expected breast cancer deaths among high-risk survivors.
  • On an annual schedule, a survivor will have an average of 4 to 5 false-positive screening results and 1 to 2 benign biopsy results over the course of their lifetime.
  • Because of the large survival benefits, the harm-benefit tradeoffs for survivors were found to be appropriate, resulting in more favorable harm-benefit ratios.

Another CCSS investigation quantified the association between temporal changes in cancer treatment over three decades and subsequent breast cancer risk.[35]

  • The cumulative incidence of breast cancer was 8.1% (95% CI, 7.3%–9.0%) by age 45 years among 11,550 female survivors (median age, 34.2 years), representing a more than sixfold excess risk (SIR, 6.6; 95% CI, 6.1–7.2), compared with age-, sex-, and calendar year–matched controls.
  • Concurrent with changes in therapy by decade, including reduced rates of chest and pelvic radiation therapy and increased rates of anthracycline chemotherapy exposure, and adjusting for age and age at diagnosis, the invasive breast cancer rate decreased 18% for every 5 years of primary cancer diagnosis era (rate ratio, 0.82; 95% CI, 0.74–0.90). This finding was largely associated with the reduced rate of chest radiation therapy.

Thyroid cancer

Thyroid cancer is observed after the following:[12,23,55,56]

  • Neck radiation therapy for Hodgkin lymphoma, acute lymphoblastic leukemia (ALL), and brain tumors.
  • Iodine I 131-metaiodobenzylguanidine (131I-MIBG) treatment for neuroblastoma.
  • TBI for HSCT.
  • Chemotherapy only, without therapeutic radiation.

The 25-year cumulative incidence of thyroid cancer among survivors of childhood cancer is 0.5%.[13] The risk of thyroid cancer among childhood cancer survivors is more than tenfold higher than that of the general population (SIR, 10.5; 95% CI, 9.1–12).[4] Significant modifiers of the radiation-related risk of thyroid cancer include the following:[27,57]

  • Female sex.
  • Younger age at exposure.
  • Longer time since exposure.
  • Radiation dose. A linear dose-response relationship between radiation exposure and thyroid cancer is observed up to 10 Gy, with a leveling off between 10 Gy and 30 Gy, and a decline in the OR at higher doses, especially in children younger than 10 years at treatment, suggesting a cell killing effect of the target cells at higher doses.[23,27,58]

In a Dutch case-control study, childhood cancer survivors with subsequent thyroid cancer were more likely to present with smaller tumors and bilateral tumors than the general population. Treatment outcomes were similar between subsequent and sporadic thyroid cancers.[59]

For information about detecting thyroid nodules and thyroid cancer, see the Thyroid nodules section.

CNS tumors

Subsequent CNS tumors represent a spectrum of histological subtypes, from high-grade gliomas to benign meningiomas. The CCSS has reported briefer latency for gliomas than for meningiomas.[60] Accurate assessment of the prevalence of low-grade and benign lesions is challenging because of the variable opinions and practices related to neuroimaging versus symptom surveillance in long-term survivors treated with cranial irradiation. Therefore, the prevalence of these tumors is likely higher than proven.

Brain tumors develop after cranial irradiation for histologically distinct brain tumors or for management of disease among ALL or non-Hodgkin lymphoma patients.[61] SIRs reported for subsequent CNS neoplasms after treatment for childhood cancer range from 8.1 to 52.3 across studies.[23]

The risk of subsequent brain tumors demonstrates a linear relationship with radiation dose.[25,60]

  • The risk of meningioma after radiation increases with radiation dose,[9] and in some studies is further potentiated with increased exposure to intrathecal methotrexate.[25] However, this finding has not been consistently replicated.[10]
  • Cavernomas have also been reported with considerable frequency after CNS irradiation but have been speculated to result from angiogenic processes as opposed to true tumorigenesis.[62,63,64]

The Dutch Long-Term Effects after Childhood Cancer (LATER) investigators have described the clinical characteristics of childhood cancer survivors who developed histologically confirmed meningiomas.[11]

  • In 6,015 childhood cancer survivors from the LATER cohort, 1,551 of whom had prior cranial radiation therapy, 93 survivors developed meningiomas.
  • Of these patients, 89 (95.7%) were treated with prior cranial radiation therapy. The median age at diagnosis was 31.8 years (range, 13.2–50.5 years).
  • Thirty of the survivors presented with synchronous meningiomas, and 84 survivors presented with symptoms. Only 16% of the meningiomas were detected in late effects clinics.
  • All survivors underwent surgery, and one-third (n = 31) of them also received radiation therapy. Twelve survivors had three or more surgeries for growth of residual tumor, recurrences, and new meningiomas. Although the extent of surgical resection was not described, the indications for radiation therapy during follow-up after surgical resection included residual tumor, recurrences, location, or new meningioma. During follow-up, 38 survivors (40.9%) developed new meningiomas, 22 (23.7%) had recurrences, and at least 4 died because of the meningioma.

Neurological sequelae associated with meningiomas can include seizures, auditory-vestibular-visual deficits, focal neurological dysfunction, and severe headaches.[9] Despite the well-established increased risk of subsequent CNS neoplasms among childhood cancer survivors treated with cranial irradiation and the growing recognition of associated morbidity, the current literature is insufficient to evaluate the potential harms and benefits of routine screening for these lesions.[65] The decision to initiate surveillance should be shared by the cancer survivor and health care provider after carefully considering the potential harms and benefits of surveillance for CNS neoplasms, such as meningioma.

Proton radiation therapy for pediatric medulloblastoma is associated with low rates of brain stem injury and secondary malignancies. The long-term effects were reported in 178 pediatric patients with medulloblastoma who were treated with surgery, proton radiation therapy, and chemotherapy between 2002 and 2016 (median follow-up, 9.3 years).[66]

  • At 10 years, eight patients (4.5%) developed a secondary tumor (benign or malignant), with median follow up of 9.1 years. Three patients (1.7%) developed a secondary malignancy.
  • In-field second malignancies were glioblastoma (n = 2), meningioma (n = 2), and high-grade glioma (n = 1). The other malignancies were one each of ovarian fibroma, plexiform fibromyxoma of the esophagus, and papillary thyroid carcinoma.
  • Four patients developed brain stem injury at a median of 4.2 years. The 5-year cumulative incidence of brain stem injury was 1.1%, and the 10-year cumulative incidence was 1.9%.

Bone and soft tissue tumors

Survivors of hereditary retinoblastoma, Ewing sarcoma, and other malignant bone tumors are at a particularly increased risk of developing subsequent bone and soft tissue tumors.[67,68,69,70,71]

  • Radiation therapy is associated with a linear dose-response relationship.[72,73]
  • After adjustment for radiation therapy, treatment with alkylating agents [13] and anthracyclines [74] have both been linked to sarcoma, with the risk increasing with cumulative drug exposure.[74]
  • Soft tissue sarcomas can be of various histological subtypes, including nonrhabdomyosarcoma soft tissue sarcomas, rhabdomyosarcoma, malignant peripheral nerve sheath tumors, Ewing/primitive neuroectodermal tumors, and other rare tumor types.

Evidence (excess risk of bone and soft tissue tumors):

  1. A nested case-control study included 228 cases and 228 matched controls within a cohort of 69,460 5-year survivors of childhood cancer. The study investigated the risks of subsequent primary bone cancer by different levels of cumulative radiation exposure and dose-response relationships according to different specific types of chemotherapy.[75]
    • Compared with unexposed bone tissue, the OR associated with bone tissue exposed to 1 to 4 Gy was 4.8-fold (95% CI, 1.2–19.6). The OR associated with bone tissue exposed to 5 to 9 Gy was 9.6-fold (95% CI, 2.4–37.4). The OR increased linearly with increasing doses of radiation (Ptrend < .001), up to 78-fold (95% CI, 9.2–669.9) for doses of 40 Gy or higher.
    • For cumulative alkylating agent doses of 10,000 to 19,999 mg/m2 and 20,000 mg/m2 or higher, the radiation-adjusted ORs were 7.1 (95% CI, 2.2–22.8) and 8.3 (95% CI, 2.8–24.4), respectively. There were independent contributions from exposure to procarbazine, ifosfamide, or cyclophosphamide.
  2. A population-based study of 69,460 5-year survivors of cancer diagnosed before age 20 years observed the following:[68,69]
    • The risk of subsequent primary bone cancer was 22-fold greater than that of the general population, with an estimated 45-year cumulative incidence of 0.6%, compared with an expected rate of 0.03% in the general population.[68]
    • The observed excess numbers of subsequent primary bone cancer declined with both age and years from diagnosis.[68]
    • The risk of subsequent soft tissue sarcoma was almost 16-fold higher than the general population, with an estimated 45-year cumulative incidence of 1.4%, compared with an expected rate of 0.1%.[69]
    • The median time from diagnosis to occurrence of a soft tissue sarcoma was 19 years.[69]
    • The most commonly observed soft tissue sarcomas were leiomyosarcoma, fibromatous neoplasms, and malignant peripheral nerve sheath tumors.[69]
    • The SIR for subsequent fibromatous primary sarcomas decreased with increasing years from diagnosis and attained age, whereas the SIR for leiomyosarcoma and malignant peripheral nerve sheath tumors remained consistently high across all years from diagnosis and at all attained ages.[69]
    • The absolute excess risks of all sarcoma subtypes were generally low, except for leiomyosarcoma that followed a retinoblastoma diagnosis (absolute excess risks, 52.7 per 10,000 person-years among survivors 45 years or more from diagnosis).[69]
    • The risk of developing a leiomyosarcoma was 30-fold higher among survivors of childhood cancer, compared with an excess risk of 0.7 for the general population.[69]
      • Retinoblastoma survivors were at the highest risk (SIR, 342.9), followed by Wilms tumor survivors (SIR, 74.2).
      • 90% of leiomyosarcomas observed after a Wilms tumor diagnosis developed within the irradiated tissue.
  3. In a CCSS cohort, an increased risk of subsequent bone or soft tissue sarcoma was associated with radiation therapy, a primary diagnosis of sarcoma, a history of other SNs, and treatment with higher doses of anthracyclines or alkylating agents.[26]
    • The 30-year cumulative incidence of subsequent sarcoma in CCSS participants was 1.08% for survivors who received radiation therapy and 0.5% for survivors who did not receive radiation therapy.
  4. Dose-risk modeling was used to study the risk of bone sarcoma in a retrospective cohort of 4,171 survivors of a childhood solid cancer treated between 1942 and 1986 (median follow-up, 26 years).[72]
    • Results demonstrated that the risk of bone sarcoma increased slightly up to a cumulative organ-absorbed radiation dose of 15 Gy (HR, 8.2; 95% CI, 1.6–42.9) and then rapidly increased for higher radiation doses (HR for 30 Gy or more, 117.9; 95% CI, 36.5–380.6), compared with patients not treated with radiation therapy.
    • The excess RR per Gy in this model was 1.77 (95% CI, 0.62–5.94).
  5. In survivors of bilateral retinoblastoma, the most commonly observed malignant SN is sarcoma, specifically osteosarcoma.[76,77,78] The contribution of chemotherapy to solid malignancy carcinogenesis was highlighted in a long-term follow-up study of 906 5-year hereditary retinoblastoma survivors who were diagnosed between 1914 and 1996 and observed through 2009.[67]
    • Treatment with alkylating agents significantly increased risk of subsequent bone tumors (HR, 1.60; 95% CI, 1.03–2.49) and leiomyosarcoma (HR, 2.67; 95% CI, 1.22–5.85) among members of the cohort.
    • Leiomyosarcoma occurrence was more common after treatment with alkylating agent chemotherapy and radiation therapy compared with radiation therapy alone (5.8% vs. 1.6% at age 40 years; P = .01).
  6. The CCSS reported the following on 105 cases and 422 matched controls in a nested case-control study of 14,372 childhood cancer survivors:[74]
    • Soft tissue sarcomas occurred at a median of 11.8 years (range, 5.3–31.3 years) from original diagnoses.
    • Any exposure to radiation was associated with increased risk of soft tissue sarcoma (OR, 4.1; 95% CI, 1.8–9.5), which demonstrated a linear dose-response relationship.
    • Anthracycline exposure was associated with soft tissue sarcoma risk (OR, 3.5; 95% CI, 1.6–7.7), independent of radiation dose.
  7. In a cohort of 952 irradiated survivors of hereditary retinoblastoma diagnosed between 1914 and 2006, CCSS investigators observed that elevated bone and soft tissue sarcoma risks differed by age, location, and sex.[78]
    • Head and neck bone and soft tissue sarcomas were diagnosed beginning in early childhood and continued well into adulthood (60-year cumulative incidence of 6.8% and 9.3%, respectively).
    • Body and extremity bone sarcoma incidence flattened after adolescence (60-year cumulative incidence, 3.5%).
    • Body and extremity soft tissue sarcoma incidence was rare until age 30 years, when incidence rose steeply (60-year cumulative incidence, 6.6%) particularly for females (60-year cumulative incidence, 9.4%).
  8. In a retrospective study of 160 patients with hereditary retinoblastoma who received radiation therapy, no correlation was identified between age (before or after 12 months) at which external-beam radiation therapy was given and development of subsequent malignancy.[70]
    • Patients with and without subsequent malignancies did not differ by RB1 variant type. Also, there was no association with variant type and location of SMN, or SMN type and age at diagnosis.
    • The study showed that patients who have a low penetrance variant and receive external-beam radiation therapy remain at risk of SMNs and should be cautiously monitored.

Skin cancer

Nonmelanoma skin cancers (NMSCs) are one of the most common SNs among childhood cancer survivors and show a strong association with radiation therapy.[4,79] Adherence to sun protection behaviors can reduce exposure to UV radiation that may exacerbate risk.

The CCSS performed a randomized, controlled, comparative effectiveness trial to test methods to improve early detection of skin cancer among survivors of childhood cancer at high risk after radiation therapy exposure. Participants were randomly assigned to the experimental arm, which included print materials in combination with mHealth strategies (text messages and use of the Advancing Survivors' Knowledge website), or the control arm. Screening rates improved by 1.5-fold in the experimental arm. Rates of physician skin examination increased from baseline to 12 months, and rates of self-examination increased from baseline to 18 months in all three intervention groups. However, the increase in rates did not differ between the intervention groups.[80]

Evidence (excess risk of NMSCs):

  1. Compared with participants who did not receive radiation therapy, CCSS participants treated with radiation therapy had a 6.3-fold increased risk of NMSCs (95% CI, 3.5–11.3).[81]
    • 90% of tumors occurred within the radiation field.
    • A CCSS case-control study of the same cohort reported on subsequent basal cell carcinomas (BCCs). Children who received 35 Gy or more to the skin site had an almost 40-fold excess risk of developing BCCs (OR, 39.8; 95% CI, 8.6–185), compared with those who did not receive radiation therapy. Results were consistent with a linear dose-response relationship, with an excess OR per Gy of 1.09 (95% CI, 0.49–2.64).
  2. In 5,843 childhood cancer survivors in the DCOG-LATER cohort, investigators found that childhood cancer survivors had a 30-fold increased risk of developing BCCs.[29]
    • After a first BCC diagnosis, 46.7% of patients developed additional BCCs.
    • BCC risk was associated with any radiation therapy to the relevant radiation field (site of BCC) (HR, 14.32) and with estimated percentage of exposed skin surface area (26%–75%: HR, 1.99; 76%–100%: HR, 2.16 vs. 1%–25% exposed; Ptrend among exposed = .002).
    • BCC risk was not associated with prescribed radiation dose and likelihood of sun-exposed skin area.
    • Of all chemotherapy groups examined, only vinca alkaloids increased the BCC risk (HR, 1.54).
  3. The occurrence of an NMSC as the first SN has been reported to identify a population at high risk of a future invasive malignant SN.[7]
    • CCSS investigators observed a cumulative incidence of a malignant neoplasm of 20.3% (95% CI, 13.0%–27.6%) at 15 years among radiation-exposed survivors who developed an NMSC as a first SN, compared with 10.7% (95% CI, 7.2%–14.2%) among survivors whose first SN was an invasive malignancy.

Malignant melanoma has also been reported as an SN in childhood cancer survivor cohorts, although at a much lower incidence than NMSCs.

Risk factors for malignant melanoma identified among these studies include the following:[82]

  • Radiation therapy.
  • Combination of alkylating agents and antimitotic drugs.

Evidence (excess risk of melanoma):

  1. A systematic review that included data from 19 original studies (total N = 151,575 survivors; median follow-up of 13 years) observed an incidence of 10.8 cases of malignant melanoma per 100,000 childhood cancer survivors per year.[82]
    • Melanomas most frequently developed in survivors of Hodgkin lymphoma, hereditary retinoblastoma, soft tissue sarcoma, and gonadal tumors. However, the relatively small number of survivors represented in the relevant studies preclude assessment of melanoma risk among other types of childhood cancer.
  2. CCSS investigators observed an approximate 2.5-fold increased risk (SIR, 2.42; 95% CI, 1.77–3.23) of melanoma among members of their cohort (median time to development, 21 years).[83]
    • The cumulative incidence of first subsequent melanoma at 35 years from initial cancer diagnosis was 0.55% (95% CI, 0.37%–0.73%), and the absolute excess risk was 0.10 per 1,000 person-years (95% CI, 0.05–0.15).
    • Family history of cancer, demographic characteristics, or treatment-related factors did not predict risk of melanoma.

Skin cancer risk after retinoblastoma

The incidence of melanoma and NMSC was evaluated in a cohort of 1,851 long-term, White survivors of retinoblastoma (1,020 hereditary and 831 nonhereditary) who were diagnosed from 1914 to 2006 and monitored through 2016.[84]

  • Of all patients, 33 hereditary and 7 nonhereditary survivors developed melanoma, and 26 hereditary and 9 nonhereditary survivors developed NMSC. The median age of skin cancer development was about 20 years younger for hereditary survivors than nonhereditary survivors.
  • Most NMSCs were on the head/neck, whereas melanomas were more broadly distributed, with patterns similar to melanoma-prone families.
  • At 50 years after retinoblastoma diagnosis, in hereditary survivors, the cumulative incidence of melanoma was 4.5% and the cumulative incidence of NMSC was 3.7%. In nonhereditary survivors, the cumulative incidence of melanoma was 0.7% and the cumulative incidence of NMSC was 1.5%.

Lung cancer

Among childhood cancer survivor cohorts, lung cancer represents a relatively uncommon SN. There is a long latent period between the childhood cancer diagnosis and the development of a lung SN.[13,85]

Evidence (excess risk of lung cancer):

  1. The 30-year cumulative incidence of lung cancer among CCSS participants was 0.16% (95% CI, 0.09%–0.23%), representing a SIR of 4.0 (95% CI, 2.9–5.4).[85]
    • Lung cancer risk demonstrated a dose-related association with chest radiation dose: 10 to 30 Gy (HR, 3.4; 95% CI, 1.05–11.0), more than 30 to 40 Gy (HR, 4.6; 95% CI, 1.5–14.3), and more than 40 Gy (HR, 9.1; 95% CI, 3.1–27.0).
    • Cumulative incidence of lung SMNs was higher among current or past smokers, compared with those who had never smoked.
    • The SIR for lung cancer was highest among survivors of Hodgkin lymphoma (SIR, 9.3; 95% CI, 6.2–13.4) and bone cancer (SIR, 4.4; 95% CI, 1.8–9.1).
  2. The 25-year cumulative incidence of lung cancer among the DCOG-LATER cohort was 0.1% (95% CI, 0.0%–0.3%).[13]
    • Incidence was approximately fourfold higher than what would be expected in the general population (SIR, 4.3; 95% CI, 1.9–8.5).
  3. Lung cancer has been reported after chest irradiation for Hodgkin lymphoma.[86]
    • The risk increases in association with longer elapsed time from diagnosis.
  4. Smoking has been linked with the occurrence of lung cancer that develops after radiation therapy for Hodgkin lymphoma.[86]
    • The increase in risk of lung cancer with increasing radiation dose is greater among patients who smoke after exposure to radiation than among those who refrain from smoking (P = .04).

Gastrointestinal (GI) cancer

There is substantial evidence that childhood cancer survivors develop GI malignancies more frequently and at a younger age than the general population. This evidence supports the need for early initiation of colorectal carcinoma surveillance.[87,88,89]

Evidence (excess risk of GI cancer):

  1. In a French and British cohort-nested, case-control study of childhood solid tumor survivors diagnosed before age 17 years, the risk of developing a digestive organ SN varied with therapy.[90]
    • The risk of GI cancer was 9.7-fold higher than in population controls.
    • The SNs most often involved the colon/rectum (42%), liver (24%), and stomach (19%).
    • A strong radiation dose-response relationship was observed, with an OR of 5.2 (95% CI, 1.7–16.0) for local radiation doses between 10 Gy to 29 Gy and 9.6 (95% CI, 2.6–35.2) for doses of 30 Gy and above, compared with survivors who had not received radiation therapy.
    • Chemotherapy alone and combined-modality therapy were associated with a significantly increased risk of developing a GI SN (SIR, 9.1; 95% CI, 2.3–23.6; SIR 29.0; 95% CI, 20.5–39.8, respectively).
  2. The PanCare Childhood and Adolescent Cancer Survivor Care and Follow-Up Studies (PanCareSurFup) consortium quantified the absolute risks by radiation therapy treatment characteristics in a cohort of 69,450 5-year childhood cancer survivors in Europe. ORs were calculated from a case-control study comprising 143 subsequent colorectal cancers within the cohort of childhood cancer survivors.[89]
    • Survivors treated with any abdominopelvic radiation therapy were three times more likely to develop a subsequent colorectal cancer than those who did not receive radiation therapy (OR, 3.1; 95% CI, 1.4–6.6).
    • By age 40 years, survivors who were treated with abdominopelvic radiation therapy already have a similar risk of colorectal cancer as individuals aged 50 years in the general population when population-based colorectal cancer screening begins.
    • The risk of colorectal cancer increases with abdominopelvic radiation therapy dose. Survivors treated with spinal or whole-abdomen radiation therapy are at higher risk than those treated with radiation to other abdominopelvic fields.
  3. CCSS investigators reported a 4.6-fold higher risk of GI SNs among their study participants than in the general population (95% CI, 3.4–6.1).[87]
    • The SNs most often involved the colon (39%), rectum/anus (16%), liver (18%), and stomach (13%).
    • The SIR for colorectal cancer was 4.2 (CI, 2.8–6.3).
    • The most prevalent GI SN histology was adenocarcinoma (56%).
    • The highest risk of GI SNs was associated with abdominal irradiation (SIR, 11.2; CI, 7.6–16.4), but survivors not exposed to radiation also had a significantly increased risk (SIR, 2.4; CI, 1.4–3.9).
    • High-dose procarbazine (RR, 3.2; CI, 1.1–9.4) and platinum drugs (RR, 7.6; CI, 2.3–25.5) independently increased the risk of GI SNs.
  4. St. Jude Children's Research Hospital investigators observed that the SIR for subsequent colorectal carcinoma was 10.9 (95% CI, 6.6–17.0) compared with U.S. population controls. Investigators also observed the following:[88]
    • Incidence of a subsequent colorectal carcinoma increased steeply with advancing attained age, with a 40-year cumulative incidence of 1.4% ± 0.53% among the entire cohort (N = 13,048) and 2.3% ± 0.83% for 5-year survivors.
    • Colorectal carcinoma risk increased by 70% with each 10 Gy increase in radiation dose. Increasing radiation volume also increased the risk.
    • Treatment with alkylating agent chemotherapy was also associated with an 8.8-fold excess risk of subsequent colorectal carcinoma.
  5. A multi-institutional prospective study observed that potentially precancerous neoplastic polyps were found in 27.8% of childhood cancer survivors who received radiation to the abdomen/pelvis at least 10 years earlier and who had colonoscopic screening between age 35 and 49 years.[91]
    • This polyp prevalence is at least as high as that previously reported for the average-risk population older than 50 years and is similar to the 24% incidence rate for patients with hereditary nonpolyposis colon cancer. Polyp prevalence rates in the general population for people aged 35 to 49 years are unclear.
  6. A DCOG-LATER record linkage study evaluated the risk of histologically confirmed colorectal adenomas among 5,843 5-year childhood cancer survivors followed for a median of 24.9 years.[92]
    • The cumulative incidence of colorectal adenoma by age 45 years was 3.6% among survivors who received abdominal pelvic radiation versus 2.0% for survivors who did not receive abdominal pelvic radiation, versus 1.0% among siblings.
    • Factors associated with adenoma risk were abdominal pelvic radiation (HR, 2.1), TBI (HR, 10.6), cisplatin (HR, 2.1 for <480 mg/m2; HR, 3.8 for ≥480 mg/m2), diagnosis of hepatoblastoma (HR, 27.1), and family history of early-onset colorectal cancer (HR, 20.5).
    • Procarbazine exposure was also associated with an increased risk among survivors not exposed to abdominal pelvic radiation or TBI (HR, 2.7).
  7. The PanCareSurFup consortium reported on digestive cancers in a cohort of 69,460 5-year childhood cancer survivors in Europe.[93]
    • Survivors of Wilms tumor (SIR, 12.1; 95% CI, 9.6–15.1) and Hodgkin lymphoma (SIR, 7.3; 95% CI, 5.9–9.0) were at the highest risk for GI SMNs.
    • By age 55 years, 2.3% of survivors of Wilms tumor and Hodgkin lymphoma developed a secondary colorectal cancer, a rate that is comparable to that of the general population with two or more first-degree relatives affected by GI cancer.
  8. A nested case-control study examined the rate of colorectal cancer according to large bowel radiation therapy dose and procarbazine dose among 5-year Hodgkin lymphoma survivors who were diagnosed between age 15 and 50 years (only 27% of cases were 15 to 24 years old) at five hospital centers in the Netherlands (diagnosed between 1964 to 2000; median follow-up, 26 years).[94]
    • The median interval between Hodgkin lymphoma diagnosis and subsequent colorectal cancer was 25.7 years (range, 18.2–31.6 years).
    • Treatment with subdiaphragmatic radiation therapy (RR, 2.4; 95% CI, 1.4–4.1) and more than 8.4 g/m2 of procarbazine (RR, 2.5; 95% CI, 1.3–5.0) were associated with increased rates of colorectal cancer on univariable analysis.
    • Colorectal cancer rate increased linearly with mean radiation therapy dose to the whole large bowel and dose to the affected bowel segment. The dose response became steeper with higher doses of procarbazine and increased 1.2-fold (95% CI, 1.1–1.3) for each 1 g/m2 increase in procarbazine.

Oral cancers

The PanCareSurFup consortium reported on risks of oral second primary neoplasms (validated through pathology reports) in a cohort of 69,460 5-year childhood cancer survivors in Europe.[95]

  • Oral second primary neoplasms (n = 145; 64 salivary gland, 38 tongue, 20 pharynx, 2 lip, and 21 other) developed in 143 survivors at a median age of 32 years. This represents a fivefold excess risk compared with that expected in the general population.
  • Childhood cancer diagnostic groups at greatest risk for an oral second primary neoplasm included leukemia (SIR, 19.2; 95% CI, 14.6–25.2), bone sarcoma (SIR, 6.4; 95% CI, 3.7–11.0), Hodgkin lymphoma (SIR, 6.2; 95% CI, 3.9–9.9), and soft tissue sarcoma (SIR, 5.0; 95% CI, 3.0–8.5).
  • Observed specific treatment associations with oral second primary neoplasms included radiation therapy and salivary gland neoplasms (SIR, 33; 95% CI, 25.3–44.5) and chemotherapy (any exposure) and tongue neoplasms (SIR, 15.9; 95% CI, 10.6–23.7).
  • Data were not available to assess the contributions of health behaviors (smoking, alcohol intake) and human papillomavirus (HPV) infection status to the development of oral second primary neoplasms.

Urogenital cancers

Development of subsequent primary urogenital cancers in childhood and adolescent cancer survivors is rare.

Using SEER data of 43,991 patients (aged <20 years) diagnosed with a first primary cancer from 1975 to 2016, the risk of urinary system cancer was higher for both females (SIR, 5.18; 95% CI, 3.65–7.14) and males (SIR, 2.80; 95% CI, 1.94–3.92), compared with the general population.[96]

  • Females were more likely than males to develop a subsequent urinary system cancer (SIR, 1.86; 95% CI, 1.13–3.03) and kidney cancer (SIR, 1.97; 95% CI, 1.11–3.53).
  • Females with any first cancer had higher risks than the general population for developing cancers of the corpus uteri (SIR, 2.32; 95% CI, 1.49–3.45) and vulva (SIR, 4.27; 95% CI, 1.38–9.95).

Renal carcinoma

Consistent with reports among survivors of adult-onset cancer, an increased risk of renal carcinoma has been observed in survivors of childhood cancer.[28,97,98] Underlying genetic predisposition may also play a role in the risk of developing renal carcinomas because rare cases of renal carcinoma have been observed in children with tuberous sclerosis.[97] Cases of secondary renal carcinoma associated with Xp11.2 translocations and TFE3 gene fusions have also been reported and suggest that cytotoxic chemotherapy may contribute to renal carcinogenesis.[99,100,101]

Evidence (excess risk of renal carcinoma):

  1. CCSS investigators reported a significant excess of subsequent renal carcinoma among 14,358 5-year survivors in the cohort (SIR, 8.0; 95% CI, 5.2–11.7) compared with the general population.[97]
    1. The reported overall absolute excess risk of 8.4 per 105 person-years indicates that these cases are relatively rare. Highest risk was observed among the following:
      • Neuroblastoma survivors (SIR, 85.8; 95% CI, 38.4–175.2).[97] Radiation has been hypothesized to predispose children with high-risk neuroblastoma to renal carcinoma.[102]
      • Those treated with renal-directed radiation therapy of 5 Gy or higher (RR, 3.8; 95% CI, 1.6–9.3).[97]
      • Those treated with platinum-based chemotherapy (RR, 3.5; 95% CI, 1.0–11.2).[97]

Human Papillomavirus (HPV)–Associated Malignancies

Evidence (HPV-associated SMNs):

  1. A CCSS study evaluated the occurrence of cancer types in which HPV is an established etiologic risk factor. The study included 24,363 childhood cancer survivors who were a median of 21 years from diagnosis.[103]
    • The 30-year cumulative incidence of an HPV-associated cancer was 0.3% (95% CI, 0.2%–0.4%), reflecting an almost threefold excess risk (SIR, 2.86; 95% CI, 2.05–4.00) to that of the general population.
    • Male and female cancer survivors had an elevated risk of HPV-associated oropharyngeal (SIR in males, 4.06; SIR in females, 8.44) and anorectal (SIR in males, 13.56; SIR in females, 9.16) SMNs. However, females were not at increased risk of cervical or vulvar cancers, compared with the general population.
    • Independent risk factors for HPV-associated cancers identified by multivariable modeling included male sex (vs. females: relative SIR, 1.99; 95% CI, 1.00–3.94); head, neck, and pelvic radiation therapy doses higher than 30 Gy (vs. none: relative SIR, 2.35; 95% CI, 1.11–4.97); and cisplatin-equivalent doses higher than 400 mg/m2 (vs. none: relative SIR, 4.51; 95% CI, 1.78–11.43).
  2. A population-based study used Surveillance, Epidemiology, and End Results (SEER) registry data to evaluate risk factors and trends for HPV-associated SMNs among 374,408 adolescent and young adult (AYA) patients (11% were aged 15–24 years, 28% were aged 25–34 years, and 61% were aged 35–44 years at diagnosis). The patients were diagnosed between 1976 and 2015.[104]
    • The incidence of HPV-associated SMNs declined over the study period, and the overall incidence of HPV-associated SMNs among AYA cancer survivors was low, affecting only 0.4% of survivors.
    • Risk of any HPV-associated SMN was increased by 70% for AYA survivors (SIR, 1.70; 95% CI, 1.61–1.79) and 117% for oropharyngeal cancer (SIR, 2.17; 95% CI, 2.00–2.35), compared with the general population.
    • Cervical cancer risk was overall lower in survivors (SIR, 0.85; 95% CI, 0.76–0.95), but Hispanic AYA survivors had a significant increase in cervical cancer (SIR, 1.46; 95% CI, 1.01–2.06).
    • Among survivors with HPV-related first cancers, prior chemotherapy and radiation therapy were associated with any HPV-related SMN. However, those therapies were not associated with HPV-related SMNs among survivors whose first cancers were not HPV related.

Survival Outcomes After SNs

Outcome after the diagnosis of an SN is variable, as treatment for some histological subtypes may be compromised if childhood cancer therapy included cumulative doses of agents and modalities at the threshold of tissue tolerance.

Using data from the SEER Program, individuals younger than 60 years with first primary malignancies (n = 1,332,203) were compared with childhood cancer survivors (n = 1,409) who had a second primary malignancy.[105]

  • Survivors of childhood cancer diagnosed with a second primary malignancy experienced poorer overall survival than did their peers without a history of cancer (HR, 1.86; 95% Cl, 1.72–2.02) after the study had accounted for cancer type, age, sex, race, and decade of diagnosis.
  • A history of childhood cancer was consistently associated with a twofold to threefold increased risk of death for the most diagnosed second primary malignancies, including breast cancer, thyroid cancer, AML, brain cancer, melanoma, bone cancer, and soft tissue sarcoma.

In a study of female participants in the CCSS who were subsequently diagnosed with breast cancer (n = 274) and matched to a control group of women (n = 1,095) with de novo breast cancer, survivors of childhood cancer were found to have elevated mortality rates (HR, 2.2; 95% CI, 1.7–3.0) even after adjusting for breast cancer treatment.[53]

  • Survivors were five times more likely to die as a result of other health-related causes, including other SMNs and cardiovascular or pulmonary disease (HR, 5.5; 95% CI, 3.4–9.0).
  • The cumulative incidence of a second asynchronous breast cancer was elevated significantly compared with controls (at 5 years, 8.0% among childhood cancer survivors vs. 2.7% among controls; P < .001).

Subsequent Neoplasms and Genetic Susceptibility

Literature clearly supports the role of chemotherapy and radiation therapy in the development of SNs. However, interindividual variability exists, suggesting that genetic variation has a role in susceptibility to genotoxic exposures, or that genetic susceptibility syndromes confer an increased risk of cancer, such as Li-Fraumeni syndrome.[106,107] In a population-based Swiss Childhood Cancer Survivor Study, cancer predisposition syndromes were associated with a high risk of second primary neoplasms before the age of 21 years and represented the most important risk factor (HR, 7.8; 95% CI, 4.8–12.7) for developing a second primary cancer.[108]

Previous studies have demonstrated that childhood cancer survivors with a family history of Li-Fraumeni syndrome in particular, or a family history of cancer, carry an increased risk of developing an SN.[109,110] A prospective registry followed 480 individuals with pathogenic or likely pathogenic germline TP53 variants.[111] Individuals who developed a first cancer were monitored for the development of a second malignant neoplasm. Among individuals who were younger than 17 years at the time of diagnosis of their first cancer, 50% developed a second cancer within 20 years.

The risk of SNs could potentially be modified by variants in high-penetrance genes that lead to these serious genetic diseases (e.g., Li-Fraumeni syndrome).[110] However, the attributable risk is expected to be very small because of the extremely low prevalence of variants in high-penetrance genes.

Likewise, children with neurofibromatosis type 1 (NF1) who develop a primary tumor are at an increased risk of SNs compared with childhood cancer survivors without NF1. Treatment with radiation, but not alkylating agents, increases the risk of SNs in survivors with NF1.[112] SNs represent a major contributor to excess mortality in adult survivors of childhood glioma with NF1.[113] These survivors developed late-onset (>5 years from diagnosis) SMNs at four times the rate of glioma survivors without NF1 (4.02; range, 2.12–7.62). The 30-year, all-cause late mortality rate was 46.3% (95% CI, 23.9%–62.2%) in glioma survivors with NF1, compared with 18% (95% CI, 16.1%–20.0%) in glioma survivors without NF1. The most common causes of death among survivors with NF1 and glioma were SNs.

Table 1 summarizes the spectrum of neoplasms, affected genes, and Mendelian mode of inheritance of selected syndromes of inherited cancer predisposition.

Table 1. Selected Syndromes of Inherited Cancer Predispositiona
Syndrome Major Tumor Types Affected Gene Mode of Inheritance
AML = acute myeloid leukemia; MDS = myelodysplastic syndromes; WAGR = Wilms tumor, aniridia, genitourinary abnormalities, and range of developmental delays.
a Adapted from Strahm et al.[114]
b Dominant in a fraction of patients, spontaneous variants can occur.
Adenomatous polyposis of the colon Colon, hepatoblastoma, intestinal cancers, stomach, thyroid cancer APC Dominant
Ataxia-telangiectasia Leukemia, lymphoma ATM Recessive
Beckwith-Wiedemann syndrome Adrenal carcinoma, hepatoblastoma, rhabdomyosarcoma, Wilms tumor CDKN1C,NSD1 Dominant
Bloom syndrome Leukemia, lymphoma, skin cancer BLM Recessive
Diamond-Blackfan anemia Colon cancer, osteogenic sarcoma, AML/MDS RPS19and otherRPgenes Dominant, spontaneousb
Fanconi anemia Gynecological tumors, leukemia, squamous cell carcinoma FANCA, FANCB, FANCC, FANCD2, FANCE, FANCF, FANCG Recessive
Juvenile polyposis syndrome Gastrointestinal tumors SMAD4 Dominant
Li-Fraumeni syndrome Adrenocortical carcinoma, brain tumor, breast carcinoma, leukemia, osteosarcoma, soft tissue sarcoma TP53 Dominant
Multiple endocrine neoplasia 1 Pancreatic islet cell tumor, parathyroid adenoma, pituitary adenoma MEN1 Dominant
Multiple endocrine neoplasia 2 Medullary thyroid carcinoma, pheochromocytoma RET Dominant
Neurofibromatosis type 1 Neurofibroma, optic pathway glioma, peripheral nerve sheath tumor NF1 Dominant
Neurofibromatosis type 2 Vestibular schwannoma NF2 Dominant
Nevoid basal cell carcinoma syndrome Basal cell carcinoma, medulloblastoma PTCH Dominant
Peutz-Jeghers syndrome Intestinal cancers, ovarian carcinoma, pancreatic carcinoma STK11 Dominant
Retinoblastoma Osteosarcoma, retinoblastoma RB1 Dominant
Tuberous sclerosis Hamartoma, renal angiomyolipoma, renal cell carcinoma TSC1,TSC2 Dominant
von Hippel-Lindau syndrome Hemangioblastoma, pheochromocytoma, renal cell carcinoma, retinal and central nervous system tumors VHL Dominant
WAGR syndrome Gonadoblastoma, Wilms tumor WT1 Dominant
Wilms tumor syndrome Wilms tumor WT1 Dominant
Xeroderma pigmentosum Leukemia, melanoma XPA, XPB, XPC, XPD, XPE, XPF, XPG, POLH Recessive

The McGill Interactive Pediatric OncoGenetic Guidelines (MIPOGG) tool identifies children with cancer who have an increased likelihood of having a cancer predisposition syndrome. This tool guides clinicians through a series of yes or no questions, and it generates a recommendation for or against genetic evaluation.[115,116]

  • In a population-based, nested, case-control study, the MIPOGG tool identified survivors who were at increased risk of developing SMNs, after controlling for radiation and chemotherapy exposures (HR, 1.53; 95% CI, 1.06–2.19).
  • SMN prediction was superior in survivors of CNS and solid tumor neoplasms and in survivors who were not irradiated during treatment of their primary malignancy.
  • Use of the MIPOGG tool in pediatric oncology patients, at diagnosis or in survivorship follow-up, may help prioritize those who should undergo genetic evaluation.

Drug-metabolizing enzymes and DNA repair polymorphisms

The interindividual variability in risk of SNs is more likely related to common polymorphisms in low-penetrance genes that regulate the availability of active drug metabolites or are responsible for DNA repair. Gene-environment interactions may magnify subtle functional differences resulting from genetic variations.

In related research, SJLIFE investigators evaluated cancer treatments and pathogenic germline variants in 127 genes from six major DNA repair pathways to identify childhood cancer survivors at an increased risk of SNs.[117]

  • Among 4,402 survivors who underwent whole-genome sequencing, 495 (11.2%) developed 1,269 SNs.
  • Among 508 survivors (11.5%), 538 pathogenic germline variants were identified in 98 DNA repair pathways (e.g., POLG, MUTYH, ERCC2, and BRCA2).

    The following three groups were identified to have an elevated risk of SNs:

    • Female survivors with variants in homologous recombination genes who were treated with high doses (≥20 Gy) of chest radiation (RR, 4.4; 95% CI, 1.6–12.4) or a cumulative dose of anthracyclines in the second or third tertile (RR, 4.4; 95% CI, 1.7–11.4) had a significantly increased risk of breast cancer.
    • Survivors with variants in homologous recombination genes who received alkylating agent doses in the third tertile had an increased rate of subsequent sarcomas (RR, 14.9; 95% CI, 4.0–38.0).
    • Survivors with variants in nucleotide excision repair genes who were treated with neck radiation (≥30 Gy) had an increased risk of subsequent thyroid cancer (RR, 12.9; 95% CI, 1.6–46.6).

Drug-metabolizing enzymes

Metabolism of genotoxic agents occurs in two phases.

  1. Phase I involves activation of substrates into highly reactive electrophilic intermediates that can damage DNA, a reaction principally performed by the cytochrome p450 (CYP) family of enzymes.
  2. Phase II enzymes (conjugation) function to inactivate genotoxic substrates. The phase II proteins comprise the glutathione S-transferase (GST) enzymes, NAD(P)H:quinone oxidoreductase-1 (NQO1) enzyme, and others.

The balance between the two sets of enzymes is critical to the cellular response to xenobiotics; for example, high activity of a phase I enzyme and low activity of a phase II enzyme can result in DNA damage.

DNA repair polymorphisms

DNA repair mechanisms protect somatic cells from variants in tumor suppressor genes and oncogenes that can lead to cancer initiation and progression. An individual's DNA repair capacity appears to be genetically determined.[118] A number of DNA repair genes contain polymorphic variants, resulting in large interindividual variations in DNA repair capacity.[118] Evaluation of the contribution of polymorphisms influencing DNA repair to the risk of SN represents an active area of research.

Polygenic risk

With the decreased use of radiation therapy, it has become important to define the role of genetic susceptibility in chemotherapy-related SMNs. SJLIFE cohort study investigators evaluated treatment-related SMNs among long-term survivors of childhood cancer. An externally validated 179-variant polygenic risk score (PRS) associated with risks of common adult-onset cancers in the general population was calculated for each survivor.[119]

  • The most frequent SMNs developing in 1,594 survivors included basal cell carcinoma (n = 822), breast cancer (n = 235), and thyroid cancer (n = 221).
  • SMN risk associations with the PRS were extremely modest in survivors with European ancestry who were exposed to radiation therapy (HR, 1.22; n = 4,630).
  • Among survivors with European ancestry who did not receive radiation therapy (n = 4,322), the increase in 30-year SMN cumulative incidence and HRs comparing top and bottom PRS quintiles was statistically significant for those treated with alkylating agents (17% vs. 6%; HR, 2.46; P < .01), anthracyclines (20% vs. 8%; HR, 2.86; P < .001), epipodophyllotoxins (23% vs. 1%; HR, 12.20; P < .001), or platinums (46% vs. 7%; HR, 8.58; P < .01).
  • Among survivors with African ancestry who did not receive radiation therapy (n = 414), the PRS also significantly predicted epipodophyllotoxin-related SMN risk. The greatest improvements in risk prediction were for survivors who were exposed to epipodophyllotoxins (HR, 2.68; P < .01).

Screening and Follow-Up for Subsequent Neoplasms

Vigilant screening is important for childhood cancer survivors at risk.[120] Because of the relatively small size of the pediatric cancer survivor population and the prevalence and time to onset of therapy-related complications, undertaking clinical studies to assess the impact of screening recommendations on the morbidity and mortality associated with the late effect is not feasible.

Well-conducted studies of large populations of childhood cancer survivors have provided compelling evidence linking specific therapeutic exposures and late effects. This evidence has been used by several national and international cooperative groups (Scottish Collegiate Guidelines Network, Children's Cancer and Leukaemia Group, Children's Oncology Group [COG], DCOG) to develop consensus-based clinical practice guidelines to increase awareness and standardize the immediate care needs of medically vulnerable childhood cancer survivors.[121]

All pediatric cancer survivor health screening guidelines employ a hybrid approach that is both evidence-based (using established associations between therapeutic exposures and late effects to identify high-risk categories) and grounded in the collective clinical experience of experts (matching the magnitude of the risk with the intensity of the screening recommendations). The screening recommendations in these guidelines represent a statement of consensus from a panel of experts in the late effects of pediatric cancer treatment.[120,121]

The COG Guidelines for malignant SNs indicate that certain high-risk populations of childhood cancer survivors merit heightened surveillance because of predisposing host, behavioral, or therapeutic factors.[120]

  • Screening for leukemia: MDS-pCT or AML-pCT usually manifests within 10 years after exposure. Recommendations include monitoring with history and physical examination for signs and symptoms of pancytopenia for 10 years after exposure to alkylating agents or topoisomerase II inhibitors.
  • Screening after radiation exposure: Most other SNs are associated with radiation exposure and usually manifest more than 10 years after exposure. Screening recommendations include careful annual physical examination of the skin and exposed (often underlying) tissues in the radiation field.

    Specific comments about screening for more common radiation-associated SNs are as follows:

    • Screening for early-onset skin cancer: Annual dermatological examination focusing on skin lesions and pigmented nevi in the radiation field is recommended. Survivors are counseled about the following:
      • Increased risk of skin cancer.
      • Potential exacerbation of risk through tanning.
      • Benefits of adhering to behaviors to protect the skin from excessive UV radiation exposure.
    • Screening for early-onset breast cancer: Because outcome after breast cancer is directly linked to stage at diagnosis, close surveillance that results in early diagnosis may improve survival.[122] Several pediatric cancer groups have endorsed the recommendation for early (before population breast cancer screening) initiation of breast cancer surveillance using mammography, breast MRI, or both imaging modalities in young women who were treated with chest irradiation.[122]

      Mammography, the most widely accepted screening tool for breast cancer in the general population, may not be the ideal screening tool by itself for radiation-related breast cancers occurring in relatively young women with dense breasts. On the basis of research among young women with inherited susceptibility to breast cancer, dual-imaging modalities may enhance early detection related to the higher sensitivity of MRI in detecting lesions in premenopausal dense breasts and the superiority of mammography in identifying ductal carcinoma in situ;[123,124,125] therefore, the American Cancer Society recommends including adjunct screening with MRI.[126] The high sensitivity and specificity in detecting early-stage lesions with dual-imaging surveillance is offset by a substantial rate of additional investigations attributable to false-positive results.[125]

      Many clinicians are concerned about potential harms related to radiation exposure associated with annual mammography in these young women. In this regard, it is important to consider that the estimated mean breast dose with contemporary standard two-view screening mammograms is about 3.85 mGy to 4.5 mGy.[127,128,129] Thus, 15 additional surveillance mammograms from age 25 to 39 years would increase the total radiation exposure in a woman treated with 20 Gy of chest radiation to 20.05775 Gy. The benefits of detection of early breast cancer lesions in high-risk women must be balanced by the risk predisposed by a 0.3% additional radiation exposure.

      To keep young women engaged in breast health surveillance, the COG Guideline recommends the following for females who received a radiation dose of 10 Gy or higher to the mantle, mediastinal, whole lung, and axillary fields:

      • Monthly breast self-examination beginning at puberty.
      • Annual clinical breast examinations beginning at puberty until age 25 years.
      • A clinical breast examination every 6 months, with annual mammograms and MRIs beginning 8 years after radiation therapy or at age 25 years (whichever occurs later).

      The risk of breast cancer in patients who received less than 10 Gy of radiation with potential impact to the breast is of a lower magnitude compared with those who received 10 Gy or higher. Monitoring of patients treated with less than 10 Gy of radiation with potential impact to the breast is determined on an individual basis after a discussion with the provider regarding the benefits and risk/harms of screening. If a decision is made to screen, the recommendations for women exposed to 10 Gy or higher are used.

    • Screening for thyroid cancer: Surveillance recommendations for thyroid cancer among survivors treated with radiation therapy to the thyroid gland vary a great deal. Consensus recommendations for surveillance were developed by the International Guidelines Harmonization Group (IGHG) with the PanCareSurFup consortium. Ultimately, neither of the two surveillance strategies, thyroid ultrasonography and neck palpation, was demonstrated to be superior. This finding highlights the need for shared decision-making between the medical provider and patient.[130]
    • Screening for subsequent CNS neoplasms: The IGHG identified a paucity of high-quality evidence for CNS screening. The group determined there was insufficient evidence to establish whether early CNS neoplasm detection results in reduced morbidity and/or mortality. Therefore, a recommendation was not made for or against MRI surveillance. Shared decision-making between the medical provider and survivor is recommended to formulate a screening plan.[65]
    • Screening for early-onset colorectal cancer: Screening of those at risk of early-onset colorectal cancer (i.e., radiation doses of 20 Gy or higher to the abdomen, pelvis, or spine) includes colonoscopy every 5 years or multitarget stool DNA test every 3 years beginning at age 30 years or 5 years after radiation therapy (whichever occurs later). For more information, see the COG Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers.

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Late Effects of the Cardiovascular System

Cardiovascular disease, after recurrence of the original cancer and development of second primary cancers, has been reported to be the leading cause of premature mortality among long-term childhood cancer survivors.[1,2,3]

Evidence (excess risk of premature cardiovascular mortality):

  1. In the North American Childhood Cancer Survivor Study (CCSS), more than 34,000 5-year survivors of childhood cancer were diagnosed and treated from 1970 to 1999.[1]
    • Participants followed for 15 years had a standardized mortality ratio (SMR) of 11.7 (95% confidence interval [CI], 9.4–14.4) for cardiac mortality.
    • Late cardiac mortality in children who were treated more recently (i.e., in the 1990s) appears to have decreased (e.g., the cumulative incidence was 0.5% in 1970–1974 vs. 0.1% in 1990–1994).
  2. In the CCSS, outcomes for patients diagnosed and treated in adolescence and early adulthood (aged >15 to <21 years) were compared with survivors of similar cancers diagnosed in childhood (aged <15 years) and the general population.[4]
    • Childhood cancer survivors (n = 5,804) had a greater SMR than early-adolescent and young adult survivors (n = 5,804) for cardiac deaths beginning 20 years after diagnosis (SMR, 5.4; 95% CI, 3.7–7.8 vs. SMR, 1.8; 95% CI, 0.7–4.3).
    • When compared with siblings of the same age, survivors of childhood cancer (n = 4,082) had a higher risk of developing grades 3 to 5 chronic cardiac conditions than early adolescents and young adults (n = 4,082) (hazard ratio [HR], 5.6 [4.5–7.1] vs. 4.3 [3.5–5.4]).
  3. Cardiac disease becomes increasingly important as survivors of childhood cancer reach mature adulthood. This finding was observed in the population-based British Childhood Cancer Survivor Study, comprised of 34,489 5-year survivors of childhood cancer diagnosed from 1940 to 2006.[2,5]
    • In survivors of childhood cancer aged 60 years and older, circulatory disease overtakes subsequent primary neoplasms as the leading cause of excess mortality (37% of the excess number of deaths observed were caused by circulatory conditions compared with 31% of excess number of deaths caused by subsequent primary neoplasms).[2]
    • The risk of both overall cardiac and cardiomyopathy/heart failure mortality was greatest among those diagnosed between 1980 and 1989. Survivors who were diagnosed from 1980 to 1989 had 28.9 times the excess number of cardiac deaths as did survivors who were diagnosed either before 1970 or from 1990 to the present.[5]

The specific late effects covered in this section include the following:

  • Cardiomyopathy/heart failure.
  • Ischemic heart disease.
  • Pericardial heart disease.
  • Valve disease.
  • Conduction disorders.
  • Cerebrovascular disease.
  • Venous thromboembolism.

This section will also briefly discuss the influence of related conditions such as hypertension, dyslipidemia, and diabetes. However, this section will not provide a detailed review of those conditions as a consequence of childhood cancer treatment. A comprehensive review of long-term cardiovascular toxicity in childhood and young adult survivors of cancer has been published.[6]

Cardiovascular Outcomes

  • Numerous studies focus on cardiac events among childhood cancer survivors. Very large cohort studies exist, many with several decades of follow-up, that are either hospital based,[7,8,9] clinical trial based,[10,11] or population based.[2,3,5]
  • Notably, the average age of these populations is still relatively young (early or mid-adulthood). Consequently, the reported risk of serious cardiovascular outcomes is very high relative to the age-matched general population, whereas the absolute risk often remains low, limiting the power of many studies.
  • Among the large studies featuring thousands of survivors, the main limitation has been inadequate ability to clinically ascertain late cardiovascular complications, with a greater reliance on either administrative records (e.g., death registries) and/or self-report or proxy-report.
  • While each study design has some inherent biases, the overall literature, based on a combination of self-reported outcomes, clinical ascertainment, and administrative data sources, is robust. These studies conclude that certain cancer-related exposures are associated with a significantly greater risk of cardiovascular morbidity and mortality in survivors.
  • Although late effects research often lags behind changes in contemporary therapy, many therapies linked to cardiovascular late effects remain in common use today. However, restricted doses of these therapies are often given to patients with biologically favorable disease presentations. In addition, dexrazoxane cardioprotection is also widely used for patients exposed to these therapies.[12,13,14]
  • Ongoing research is important to ensure that use of newer targeted agents does not result in unexpected cardiovascular effects.[15]

Evidence (selected cohort studies describing cardiovascular outcomes):

  1. A case-control study of the PanCareSurFup and ProCardio cohort evaluated treatment-related risk factors for heart failure in survivors of childhood cancer (5 or more years) diagnosed between 1940 and 2009.[16]
    • The 50-year cumulative incidence of heart failure among the entire cohort was 2% (95% CI, 1.7%–2.2%).
    • A subcohort study evaluated 500 cases with symptomatic heart failure and 500 controls without heart failure (matched for sex, age, calendar year of first diagnosis, and length of follow-up) for whom detailed treatment exposures were available. The risk of heart failure was increased more than fivefold (odds ratio [OR], 5.5; 95% CI, 2.5–12.3) among survivors who received a mean heart radiation therapy dose of 5 Gy to 15 Gy or less, compared with those who did not receive heart radiation therapy. The risk increased with a larger volume of radiation exposing the heart.
    • Heart failure risk increased in a linear fashion with higher mean heart radiation therapy doses.
    • Survivors who received a cumulative anthracycline dose of more than 100 mg/m2 had a substantially increased risk of heart failure (OR, 5.8; 95% CI, 2.9–11.3 for 100 to <250 mg/m2 and OR, 21.2; 95% CI, 11.4–39.2 for >250 mg/m2).
    • An anthracycline dose of less than 100 mg/m2 was not a significant risk factor for heart failure.
  2. CCSS investigators reported on major cardiac events among participants diagnosed with childhood cancer between 1970 and 1999.[17]
    • In this update, the 20-year cumulative incidence of heart failure and coronary artery disease for patients treated in the 1990s declined over the decades to 0.54% and 0.19%, respectively, but was significant only for coronary artery disease.
    • The risk of coronary artery disease was significantly decreased from the 1970s, 1980s, and 1990s (0.38%, 0.24%, and 0.19%, respectively; HR, 0.65) and was attributed to historical reductions in exposure to cardiac radiation, particularly among survivors of Hodgkin lymphoma.
    • For patients treated in the 1990s, the 20-year cumulative incidence was 0.05% for valvular disease, 0.03% for pericardial disease, and 0.13% for arrhythmias. These numbers did not change over the eras (1970–1990).
  3. In the CCSS, data from 24,214 5-year survivors diagnosed between 1970 and 1999 were used to assess the impacts of radiation therapy dose and exposed cardiac volume, select chemotherapeutic agents, and age at exposure on the risk of late-onset cardiac disease.[18]
    • The cumulative incidence of cardiac disease (any cardiac disease, coronary artery disease, and heart failure) 30 years from diagnosis was 4.8%. Male survivors were more likely to develop coronary artery disease and less likely to develop heart failure than were female survivors. Non-Hispanic Black survivors were more likely to develop any cardiac disease than were non-Hispanic White survivors.
    • Low-to-moderate radiation therapy doses (5.0–19.9 Gy) to large cardiac volumes (>50% of the heart) were associated with a 1.6-fold increased risk of cardiac disease compared with survivors who did not have any cardiac radiation therapy exposure.
    • High doses (>20 Gy) to small cardiac volumes (0.1%–29.9%) were associated with an elevated rate of cardiac disease compared with unexposed survivors.
    • A dose-response relationship was observed between anthracycline exposure and heart failure, with younger children (<13 years) at the greatest risk of heart failure after comparable dosing.
  4. Another CCSS study evaluated radiation dose–response relationships for cardiac substructures and cardiac outcomes among 25,481 5-year survivors treated between 1970 to 1999. Of these survivors, 48.2% were exposed to radiation therapy.[19]
    • At a median age of 30 years, the cumulative incidence (35 years from diagnosis) was 3.9% (95% CI, 3.4%–4.3%) for coronary artery disease, 3.8% (95% CI, 3.4%–4.2%) for heart failure, 1.2% (95% CI, 1.0%–1.5%) for valvular disease, and 1.4% (95% CI, 1.1%–1.96%) for arrythmia.
    • Mean doses of 5 to 9.9 Gy to the whole heart did not increase the risk of any cardiac disease, whereas mean doses of 5 to 9.9 Gy to the right coronary artery (relative risk [RR], 2.6; 95% CI, 1.6–4.1) and left ventricle (RR, 2.2; 95% CI, 1.3–3.7) increased the risk of coronary artery disease.
    • Mean doses of 5 to 9.9 Gy to the tricuspid valve (RR, 5.5; 95% CI, 2.0–15.1) and right ventricle (RR, 8.4; 95% CI, 3.7–19.0) increased the risk of valvular disease.
    • Statistical modeling suggested that any radiation to the cardiac substructures elevate the risk of cardiac diseases, and there is no threshold dose that can mitigate this risk.
  5. A cross-sectional CCSS study included 571 adult-aged survivors of childhood cancer (median age, 37.7 years; 28.5 years from cancer diagnosis). The study compared rates of underdiagnosis and undertreatment of modifiable risk factors among survivors and respondents to the National Health and Nutrition Examination Survey (NHNES).[20]
    • Rates of cardiovascular disease risk factor underdiagnosis were similar (27.1% of survivors vs. 26.1% of participants from the NHNES; P = .73). However, survivors were more likely to be undertreated (21.0% versus 13.9%, P = .007; OR, 1.8; 95% CI, 1.2–2.7).
    • Hypertension (18.9%) and dyslipidemia (16.3%) represented the most underdiagnosed and undertreated risk factors.
    • Men and survivors who were overweight or had obesity were more likely to be underdiagnosed and undertreated.
    • These adult-aged childhood cancer survivors were nearly twice as likely to be undertreated for these conditions.
  6. Dyslipidemia is more common and is an independent predictor of cardiovascular disease among survivors, compared with controls. Specific lipid abnormalities and the risk of atherosclerotic cardiovascular disease were investigated in 4,115 childhood cancer survivors from the St. Jude Life (SJLIFE) cohort.[21]
    • Of this cohort, 3,406 survivors did not have a previous dyslipidemia diagnosis.
    • Low HDL cholesterol (HR, 2.9) and elevated triglycerides (HR, 3.1) were associated with an increased risk of myocardial infarction.
    • Diagnosis of high LDL cholesterol (HR, 2.2), high non-HDL cholesterol (HR, 2.2), low HDL cholesterol (HR, 3.9), and elevated triglycerides (HR, 3.8) were associated with an increased risk of cardiomyopathy.
  7. A Dutch CCSS-LATER study evaluated the prevalence of and risk factors for hypertension in childhood cancer survivors (median age, 32.5 years; median follow-up, 25.5 years) who were treated with potentially nephrotoxic therapies.[22]
    • Survivors (16.3%) and controls (18.2%) had comparable rates of hypertension. Undiagnosed hypertension was prevalent in 12% of survivors and 17.8% of controls.
    • Treatment factors associated with risk of hypertension included abdominal radiation therapy of more than 20 Gy and total-body irradiation (TBI).
    • Among childhood cancer survivors, glomerular filtration rate (GFR) of less than 60 mL/min/1.73 m2 was significantly associated with hypertension (OR, 3.4; 95% CI, 1.4–8.5).
  8. The CCSS demonstrated that the cumulative incidence of serious cardiac events (myocardial infarction, congestive heart failure, pericardial disease, and valvular abnormalities) in childhood cancer survivors continues to increase beyond age 45 years.[7]
    • The risk of these events was potentiated (i.e., beyond what would be expected by an additive model) by the presence of concurrent, but potentially modifiable, conditions such as obesity, dyslipidemia, diabetes, and, particularly, hypertension.
    • Hypertension was independently associated with all serious cardiac outcomes (rate ratios, 6-fold to 19-fold), even after adjustment for anthracycline use and chest irradiation.
  9. Of 670 survivors of Hodgkin lymphoma who were treated at St. Jude Children's Research Hospital (SJCRH) and survived 10 or more years, 348 patients were clinically assessed in the SJLIFE cohort study.[23]
    • Overall, survivors had a higher cumulative burden (a novel measurement of disease burden that incorporates multiple health conditions and recurrent events into a single metric) than community controls, with the total grade 3 to 5 cumulative burden among survivors at age 30 years being comparable with that of community controls at 50 years.
    • At age 50 years, the cumulative incidence of those survivors experiencing at least one grade 3 to grade 5 cardiovascular condition was 45.5% (95% CI, 36.6%–54.3%), compared with 15.7% (95% CI, 7.0%–24.4%) in community controls.
    • Myocardial infarction and structural heart defects were the major contributors to the excess grade 3 to grade 5 cumulative burden in survivors, whereas there was no notable difference in survivors and community controls at age 50 years for grades 3 to 5 cumulative burden of dyslipidemia and essential hypertension.
  10. Another SJLIFE cohort study compared the prevalence of major and minor electrocardiography (ECG) abnormalities among 2,715 participants and 268 community controls.[24]
    • Major ECG abnormalities were significantly more prevalent in survivors (10.7%) than in controls (4.9%). The most common abnormalities included isolated ST-T wave abnormalities (7.2%), evidence of myocardial infarction (3.7%), and left ventricular hypertrophy with strain pattern (2.8%).
    • Treatment exposures predicting increased risk of major abnormalities were anthracycline doses of 300 mg/m2 or greater (OR, 1.7; 95% CI, 1.1–2.5) and cardiac radiation (OR, 2.1; 95% CI, 1.5–2.9 [0.01–19.99 Gy]; OR, 2.6; 95% CI, 1.6–3.9 [20–29.99 Gy]; OR, 10.5; 95% CI, 6.5–16.9 [≥30 Gy]).
    • Major ECG abnormalities were predictive of all-cause mortality (HR, 4.0; 95% CI, 2.1–7.8).
  11. In the Teenage and Young Adult Cancer Survivor Study, cardiac mortality was investigated in more than 200,000 5-year survivors of adolescent and young adult cancer (aged 15–39 years).[3]
    • Age at diagnosis and type of cancer were identified as being important in determining risk of cardiac mortality.
    • The SMRs for all cardiac disease combined was greatest for individuals diagnosed at age 15 to 19 years (4.2), decreasing to 1.2 for individuals aged 35 to 39 years (2-sided P for trend < .0001). This age effect was most apparent for survivors of Hodgkin lymphoma, who were also found to be at greatest risk overall.
    • Limitations of this study included lack of detailed information on exposures to radiation therapy (doses, fields), exposures to chemotherapy (primarily anthracycline dose), and cardiovascular risk factors (e.g., smoking, obesity, hypertension, diabetes, family history).
  12. Dutch investigators evaluated the risk of heart failure, temporal changes by treatment periods, and the risk factors for heart failure in 6,165 childhood cancer survivors (median age, 27.3 years; median follow-up, 19.8 years) diagnosed between 1963 and 2002.[25]
    • The cumulative incidence of developing a heart failure 40 years after a childhood cancer diagnosis was 4.4% (3.4%–5.5%) among cohort members.
    • The 20-year cumulative incidence of grade 3 or higher heart failure was greater among survivors treated in the more recent treatment periods (for survivors diagnosed between 1990 and 2001, 1.5%; between 1980 and 1989, 1.6%; and between 1970 and 1979, 0.5%) than in survivors treated earlier; however, mortality caused by heart failure decreased in the patients who were treated in the more recent periods.
    • Multivariable analysis demonstrated that patients who received higher doses of mitoxantrone or cyclophosphamide had an increased risk of heart failure compared with survivors who were exposed to lower doses.
  13. The Pediatric Normal Tissue Effects in the Clinic (PENTEC) initiative reported on the risk of late cardiac disease for childhood cancer survivors who were treated with chemotherapy or radiation therapy.[26]
    • For each 10-Gy increase in corrected mean cardiac radiation dose in 1.8- to 2.0-Gy fractions, the estimated HRs were 2.01 (95% CI, 1.79–2.25) for coronary artery disease, 1.87 (95% CI, 1.70–2.06) for heart failure, 1.87 (95% CI, 1.78–1.96) for valvular disease, and 1.88 (95% CI, 1.75–2.03) for any cardiac disease.
    • For each 100-mg/m2 increase in cumulative anthracycline dose, the HR was 1.93 (95% CI, 1.58–2.36) for the development of heart failure, which is equivalent to an increase in mean heart radiation dose of approximately 10.5 Gy.

Treatment Risk Factors

Chemotherapy (in particular, anthracyclines and anthraquinones) and radiation therapy, both independently and in combination, increase the risk of cardiovascular disease in survivors of childhood cancer and are considered to be the most important risk factors contributing to premature cardiovascular disease in this population.[3,9,16,27]

Anthracyclines and related agents

Anthracyclines (e.g., doxorubicin, daunorubicin, idarubicin, and epirubicin) and anthraquinones (e.g., mitoxantrone) are known to directly injure cardiomyocytes through inhibition of topoisomerase 2-beta in cardiomyocytes and formation of reactive oxygen species, resulting in activation of cell-death pathways and inhibition of mitochondrial apoptosis.[28,29] The downstream results of cell death are changes in heart structure, including wall thinning, which leads to ventricular overload and pathological remodeling that, over time, leads to dysfunction and eventual clinical heart failure.[30,31]

Risk factors for anthracycline-related cardiomyopathy include the following:[18,32]

  • Cumulative dose, particularly greater than 250 to 300 mg/m2.
  • Younger age at time of exposure, particularly children younger than 5 years.
  • Increased time from exposure.
  • While there is no definitive safe lower dose threshold, doses in excess of 250 to 300 mg/m2 have been associated with a substantially increased risk of cardiomyopathy, with cumulative incidences exceeding 5% after 20 years of follow-up, and in some subgroups, reaching or exceeding 10% cumulative incidence by age 40 years.[17,18,31]
  • Concurrent chest or heart radiation therapy also further increases risk of cardiomyopathy,[9,27,33] as does the presence of other cardiometabolic traits such as hypertension.[7,34]
  • While development of clinical heart failure can occur within a few years after anthracycline exposure, in most survivors—even those who received very high doses—clinical manifestations may not occur for decades.

Anthracycline dose equivalency

Traditionally, anthracycline dose equivalence has largely been based on acute hematologic toxicity equivalence rather than late cardiac toxicity.

  • Analyses that pooled data from more than 28,000 long-term childhood cancer survivors monitored through age 40 years (resulting in 399 cardiomyopathy cases) have challenged previous assumptions that consider daunorubicin equivalent or nearly equivalent to doxorubicin.[35,36]
    • These investigations found that daunorubicin may be significantly less cardiotoxic than doxorubicin (equivalence ratio, 0.5; 95% CI, 0.4–0.7).[35]
    • Compared with doxorubicin, mitoxantrone may be significantly more cardiotoxic than previously thought (equivalence ratio, 10.5; 95% CI, 6.2–19.1), while epirubicin appeared to be doxorubicin isoequivalent (equivalence ratio, 0.8; 95% CI, 0.3–1.4).[36]
    • Data were too sparse to compare idarubicin with doxorubicin.

Anthracycline cardioprotection

Cardioprotective strategies that have been explored include the following:

  • New, less cardiotoxic agents and liposomal formulations. In general, data on whether liposomal formulations of anthracyclines reduce cardiac toxicity in children are limited.[37,38]
  • Prolonged infusion time. Prolonged infusion time has been associated with reduced heart failure in adult patients, but not in children.[39,40]
  • Concurrent administration of cardioprotectants. A variety of agents have been tested as cardioprotectants (amifostine, acetylcysteine, calcium channel blockers, carvedilol, coenzyme Q10, and L-carnitine), but none were beneficial and are not considered standard of care.[41,42]
  • Dexrazoxane. There are more data for dexrazoxane as a cardioprotectant, but mainly in adult patients with cancer. In particular, the U.S. Food and Drug Administration approved dexrazoxane for women with metastatic breast cancer who have received 300 mg/m2 of anthracyclines and who may benefit from further anthracycline-based therapy.[41]
    • Pediatric data show that dexrazoxane may ameliorate some markers of early cardiac toxicity for up to 5 years after therapy.[43,44,45,46]
    • Dexrazoxane may be associated with an increased risk of acute toxicities in some regimens.[47]
    • A long-term study assessed outcomes of newly diagnosed children with cancer who were treated with dexrazoxane-containing regimens in randomized clinical trials (cumulative prescribed doxorubicin dose, 100–360 mg/m2; median follow-up, 18.6 years). Dexrazoxane was not associated with cancer relapse (HR, 0.84; 95% CI, 0.63–1.13), second cancers (HR, 1.19; 95% CI, 0.62–2.30), all-cause mortality (HR, 1.07; 95% CI, 0.78–1.47), or cardiovascular mortality (HR, 1.45; 95% CI, 0.41–5.16).[48]
    • Another study evaluated long-term cardiac outcomes of 195 children with acute lymphoblastic leukemia or Hodgkin lymphoma who received doxorubicin with or without dexrazoxane in four randomized trials and patients with osteosarcoma who all received doxorubicin with dexrazoxane in a nonrandomized trial.[49]
      • At 18.1 years since cancer diagnosis (51% dexrazoxane exposed; cumulative doxorubicin dose, 297 mg/m2), dexrazoxane administration was associated with superior left ventricular fractional shortening (absolute difference, 1.4%; 95% CI, 0.3–2.5) and ejection fraction (absolute difference, 1.6%; 95% CI, 0.0–3.2) and lower myocardial stress per B-type natriuretic peptide (-6.7 pg/mL; 95% CI, -10.6 to -2.8).
      • Dexrazoxane use was associated with a reduced risk of lower left ventricular function (30% fractional shortening or 50% ejection fraction; OR, 0.24; 95% CI, 0.07–0.81), which was primarily observed in those treated with cumulative doxorubicin doses of 250 mg/m2 or higher.

Radiation therapy

While anthracyclines directly damage cardiomyocytes, radiation therapy primarily affects the fine vasculature of affected organs.[6]

Cardiovascular disease

Late effects of radiation therapy to the heart specifically include the following:

  • Delayed pericarditis, which can present abruptly or as a chronic pericardial effusion.
  • Pancarditis that includes pericardial and myocardial fibrosis, with or without endocardial fibroelastosis.
  • Cardiomyopathy (in the absence of significant pericardial disease), which can occur even without anthracycline exposure.
  • Ischemic heart disease.
  • Functional valve injury, often aortic.
  • Conduction defects.

These cardiac late effects are related to the following:

  • Individual radiation fraction size.
  • Volume of the heart that is exposed to radiation.[18,50]
  • Total radiation dose.
    • Various studies have demonstrated a substantially increased risk of these outcomes with higher radiation doses, particularly doses to the heart exceeding 35 Gy.[9,11,17,18,27]
    • At higher radiation doses, rates of heart failure, pericardial disease, and valvular disease have been reported to exceed 10% after 20 to 30 years. Although some studies suggest that doses less than 5 Gy may be associated with an increased risk of cardiovascular disease, the relative risk is small (i.e., 2.5) and the 95% CI is large (i.e., 0.2–41.5); moreover, the dosimetric analyses are generally estimations of incidental cardiac exposure.[9,17,27]
    • Low to moderate doses of radiation therapy (5.0–19.9 Gy) to large cardiac volumes (>50% of the heart) are associated with an increased rate of cardiac disease (i.e., 1.6-fold) compared with survivors who did not have any cardiac radiation therapy exposure.[18]
    • High doses of radiation (>20 Gy) to small cardiac volumes (0.1%–29.9%) are associated with an elevated rate of cardiac disease (relative rate, 2.4).[18,51]
    • Additional confirmatory data are needed for an accurate assessment of risk at very low cardiac doses.
    • Similar to anthracyclines, manifestation of these late effects may take years, if not decades, to present.

Patients who were exposed to both radiation therapy affecting the cardiovascular system and cardiotoxic chemotherapy agents are at even greater risk of late cardiovascular outcomes.[9,18] This risk may be decreasing based on Children's Oncology Group (COG) Hodgkin lymphoma clinical trials spanning from 2002 to 2022.[52]

  • In a cohort study of 2,563 patients with Hodgkin lymphoma treated in four consecutive COG clinical trials between 2002 and 2022 (AHOD0031, AHOD0831, AHOD1331, S1826), the cumulative incidence of grades 3 to 5 cardiac disease was estimated to decrease, from 10% in the first trial to 6% in the last trial.
  • All patients received doxorubicin, 1,362 received mediastinal radiation therapy, and 307 received the cardioprotectant dexrazoxane (80% of children in the S1826 study). Radiation therapy was substantially reduced and refined, whereas the anthracycline doses were increased.
  • Based on modeling used as part of this study, survivors treated in the recent high-risk Hodgkin lymphoma trial (S1826), the 30-year risk of serious cardiac morbidity will be increased less than 2% above the expected rate in an untreated population (5%). Reductions in the proportion of children receiving mediastinal radiation therapy and increases in dexrazoxane use were estimated to offset the increased doxorubicin dose, producing a net reduction in late cardiac disease.
  • These results suggest that cardiac toxic effects are estimated to decrease from older to newer Hodgkin lymphoma trials, even in females aged 12 years and younger, who are most susceptible to anthracycline-induced heart failure.

Cerebrovascular disease

Cerebrovascular disease after radiation therapy exposure is another potential late effect observed in survivors.

  • Radiation-induced vascular damage is a complex process that involves both arterial and capillary damage, with veins being less sensitive.
  • The spectrum of abnormalities includes lacunar lesions, vascular malformations, telangiectasias, intracranial hemorrhage, moyamoya, microbleeds, and cavernomas, each with potential symptomatic consequences.[53,54]
  • While brain tumor survivors have traditionally had the greatest risk, other survivors exposed to cranial irradiation (≥18 Gy) and neck irradiation (≥40 Gy), such as leukemia and lymphoma survivors, have also been reported to be at increased risk.[55,56,57,58]
  • In a PENTEC analysis, risk of cerebrovascular toxicity and future risk of stroke were analyzed and modeled (COX proportional hazards and baseline cumulative incidences of stroke in nonradiation therapy exposed, age-matched cancer patients and the general population).[59]
    • Of 3,898 pediatric patients analyzed in five reports, 101 experienced at least one cerebrovascular toxicity (e.g., transient ischemic attack [TIA], stroke, moyamoya, or arteriopathy).
    • The risk of any cerebrovascular toxicity was 0.2% at 30 Gy, 1.3% at 45 Gy, and 4.4% at 54 Gy (D50, 75.6 Gy; 68.4–89.4 Gy).
    • At an attained age of 35 years, the predicted stroke incidence at d doses was 0.9% to 1.3% at 30 Gy, 1.8% to 2.7% at 45 Gy, and 2.8% to 4.1% at 54 Gy (population baseline risk, 0.2%–0.3%).
    • At an attained age of 45 years, the predicted stroke incidence was 2.1% to 4.2% at 30 Gy, 4.5% to 8.6% at 45 Gy, and 6.7% to 13.0% at 54 Gy (population baseline risk, 0.5%–1.0%).
    • Thus, the risk of future cerebrovascular toxicity continues to rise as follow-up duration increases. Additionally, because the stroke hazard was based on prescribed tumor bed dose rather than circle-of-Willis dose, the reported stroke risk was likely underestimated.
  • In lymphoma survivors who received only chest and/or neck radiation therapy, cerebrovascular disease is thought to be caused by large-vessel atherosclerosis and cardiac embolism.[56]
  • The risk increases with cumulative dose received. One study (N = 325) reported that the stroke hazard increased by 5% (HR, 1.05; 95% CI, 1.01–1.09; P = .02), with each 1 Gy increase in the radiation dose, leading to a cumulative incidence of 2% for the first stroke after 5 years and 4% after 10 years.[60]
  • Survivors who experienced a stroke were at much greater risk of recurrent strokes.[61]

Evidence (selected studies describing prevalence of and risk factors for cerebrovascular accident [CVA]/vascular disease):

  1. The population-based British Childhood Cancer Survivor Study (n = 13,457) used Hospital Episode Statistics data for England to assess the risk of cerebrovascular-related hospitalizations (e.g., nontraumatic intracranial hemorrhage, cerebral infarction, or cerebral artery occlusion), particularly in patients older than 50 years.[58]
    • They found that 2.3% of the survivors had been hospitalized at least once for cerebrovascular disease, with a fourfold risk compared with the expected rate.
    • Survivors of central nervous system (CNS) tumors or leukemia who received cranial irradiation were at greatest risk of cerebrovascular disease (CNS tumor standardized hospitalization ratio [SHR], 15.6; 95% CI, 14.0–17.4 and leukemia SHR, 5.4; 95% CI, 4.5–6.4).
    • Beyond age 60 years, on average, 3.1% of CNS tumor survivors treated with cranial irradiation were hospitalized annually for cerebrovascular disease. By age 65 years, as many as 26% of these patients will have been hospitalized for a cerebrovascular event.
  2. CCSS investigators observed that 295 of 13,060 participants (35% treated with cranial radiation therapy) reported having a stroke (6.3%; 95% CI, 5.1%–7.5%) by age 50 years (median follow-up, 19 years). For survivors considered to be high risk, the cumulative incidence of cerebrovascular disease up to age 50 was 19.9%.[62]
  3. A retrospective study of 3,172 5-year survivors of childhood cancer monitored for a mean time of 26 years was formed from the Euro2K cohort, which included eight centers in France and the United Kingdom. Radiation doses to the circle of Willis were estimated for each of the 2,202 children who received radiation therapy.[63]
    • Patients who received radiation therapy had an 8.5-fold increased risk (95% CI, 6.3–11.0) of stroke in contrast to a nonelevated risk for patients who did not receive radiation therapy.
    • The relative risk was 15.7 (95% CI, 4.9–50.2) for doses of 40 Gy or higher.
    • At age 45 years, the cumulative incidence was 11.3% (95% CI, 7.1%–17.7%) in patients who received 10 Gy or higher to the circle of Willis, compared with 1% in the general population.
  4. Investigators from the Teenage and Young Adult Cancer Survivor Study (N = 178,962) evaluated the risk of hospitalization for a cerebrovascular event among 5-year survivors of cancer diagnosed between age 15 and 39 years.[64]
    • The investigators found that survivors of adolescent and young adult cancers had a 40% increased risk of hospitalization for cerebrovascular event compared with the general population.
    • Survivors of CNS tumors (SHR, 4.6), head and neck tumors (SHR, 2.6), and leukemia (SHR, 2.5) had the highest risk of hospitalization for a cerebrovascular complication.
    • Males had significantly higher absolute excess risks than did females, especially among head and neck tumor survivors. By age 60 years, 9% of CNS tumor survivors, 6% of head and neck tumor survivors, and 5% of leukemia survivors had been hospitalized for a cerebrovascular event.
    • The risk of hospitalization for a cerebral infarction was particularly increased among survivors of a CNS tumor older than 60 years, whereas this risk was increased across all ages in survivors of head and neck tumors.
  5. CCSS investigators evaluated the rates and predictors of recurrent stroke among participants who reported a first stroke.[61]
    • Among responding participants (329 of 443), 271 confirmed a first stroke (at median age, 19 years) and 70 reported a second stroke (at median age, 32 years).
    • Independent predictors of recurrent stroke included treatment with a cranial radiation therapy dose of 50 Gy or higher (vs. no cranial radiation therapy), history of hypertension, and age 40 years or older at first stroke (vs. age 0–17 years).
    • The 10-year cumulative incidence of late recurrent stroke was 21% overall and 33% for those treated with 50 Gy or higher of cranial radiation therapy.
    • A follow-up study of 224 CCSS participants who experienced stroke demonstrated an increased risk of all-cause and health-related mortality and a negative impact on social attainment, neurocognitive function, emotional distress, and other health-related quality-of-life measures.[65]
  6. A multicenter retrospective Dutch study evaluated 5-year survivors of Hodgkin lymphoma diagnosed before age 51 years (25% pediatric-aged patients) who were followed for a median of 18 years. Among 2,201 survivors, 96 developed cerebrovascular disease (CVA and TIA).[56]
    • Most ischemic events were from large-artery atherosclerosis (36%) or cardiac embolism (24%).
    • The cumulative incidence of ischemic CVA or TIA 30 years after lymphoma treatment was 7%.
    • The overall standardized incidence ratio (SIR) was 2.2 for CVA and 3.1 for TIA. However, SIR estimates appeared to be greater among childhood cancer survivors, with SIRs of 3.8 for CVA and 7.6 for TIA.
    • Irradiation to the neck and mediastinum was an independent risk factor for ischemic cerebrovascular disease (HR, 2.5; 95% CI, 1.1–5.6) versus no radiation therapy. Treatment with chemotherapy was not associated with increased risk.
    • Hypertension, diabetes mellitus, and hypercholesterolemia were associated with the occurrence of ischemic cerebrovascular disease.

Venous thromboembolism

Children with cancer have an excess risk of venous thromboembolism within the first 5 years after diagnosis. However, the long-term risk of venous thromboembolism among childhood cancer survivors has not been well studied.[66]

CCSS investigators evaluated self-reported late-onset (5 or more years after cancer diagnosis) venous thromboembolism among cohort members (median follow-up, 21.3 years).[67]

  • The 35-year cumulative incidence of venous thromboembolism among survivors was 4.9%. This risk was twofold higher when compared with a sibling cohort (rate ratio, 2.2; 95% CI, 1.7–2.8).
  • Risk factors for venous thromboembolism among survivors included female sex, treatment with cisplatin or asparaginase, being affected by obesity or underweight, and recurrent primary or subsequent cancer.
  • The risk of late venous thromboembolism was higher among survivors of lower-extremity osteosarcoma treated with limb-sparing surgery compared with patients treated with amputation, possibly resulting from alterations in peripheral vascular anatomy and homeostasis.
  • Venous thromboembolism was associated with an almost-twofold increased risk of late mortality (RR, 1.9; 95% CI, 1.6–2.3).

Conventional cardiovascular conditions

  • Various cancer treatment exposures may also directly or indirectly influence the development of hypertension, diabetes mellitus, and dyslipidemia.
  • These conditions remain important among cancer survivors, as they do in the general population, in that they are independent risk factors in the development of cardiomyopathy, ischemic heart disease, and cerebrovascular disease.[7,68,69,70,71]
  • Childhood cancer survivors should be closely monitored for the development of these cardiovascular conditions because they represent potentially modifiable targets for intervention.
  • Related conditions such as obesity and various endocrinopathies (e.g., hypothyroidism, hypogonadism, growth hormone deficiency) that may be more common among subsets of childhood cancer survivors also need to be monitored. If these conditions are untreated/uncontrolled, they may be associated with a metabolic profile that increases cardiovascular risk.[8] For more information, see the Risk prediction for cardiovascular diseases section.

Other Risk Factors

  • Sex. Some, but not all, studies suggest that female sex may be associated with a greater risk of anthracycline-related cardiomyopathy.[6]
  • Genetics. There is emerging evidence that genetic factors, such as single nucleotide polymorphisms in genes regulating drug metabolism and distribution, could explain the heterogeneity in susceptibility to anthracycline-mediated cardiac injury.[72,73,74,75,76,77,78,79,80] However, these genetic findings still require additional validation before integration into any clinical screening algorithm.[80]

Peripartum Cardiac Dysfunction

Long-term survivors of childhood, adolescent, and young adult malignancies with past exposure to potentially cardiotoxic treatments are at risk of peripartum cardiac dysfunction.

In the general population, peripartum cardiomyopathy (PPCM) is a rare condition characterized by heart failure during pregnancy (usually the last trimester or <5 months postpartum). The estimated incidence in the general population is 1 case per 3,000 live births.[81]

There are limited data available about the prevalence in survivors of pediatric, adolescent, and young adult malignancies who have received cardiotoxic therapies.

  • In a retrospective series from SJCRH, 3 cases of peripartum cardiac dysfunction occurred in 1,554 completed pregnancies, which was an incidence of 0.2%; 27% of the 847 long-term survivors had not been exposed to cardiotoxic therapies.[82]
  • In a series of 64 women who had all received cardiotoxic therapy (44% received chest radiation therapy plus anthracyclines, 14% received chest radiation therapy, 42% received anthracycline alone), 5 women (7.8%) had peripartum cardiac events (3 symptomatic, 2 subclinical). Of the 110 live births, 2 involved PPCM, representing a 55-fold increased risk over the general population. Risk factors were younger age at cancer diagnosis and higher anthracycline dose. Postpartum cardiac function failed to return to baseline in four women (80%).[83]
  • A single-center study estimated the risk of developing congestive heart failure (CHF) during pregnancy as 1 out of 3 female cancer survivors with a history of cardiotoxicity.[84] Seventy-eight consecutive female cancer survivors previously exposed to potentially cardiotoxic treatments (chemotherapy and/or radiation therapy to the thorax as children, adolescents or young adults) who had 94 pregnancies were retrospectively identified through high-risk clinics between 2005 and 2015.
    • A total of 55 women received anthracyclines (range, 90–500 mg/m2), while 23 received nonanthracycline chemotherapy and/or radiation therapy only. Of the 13 women with prior cardiotoxicity, 8 had reduced left ventricular ejection fraction at the first antenatal visit. CHF occurred in five pregnancies (4 women; 5.3%).
    • The incidence of CHF was 31% for women with a history of cardiotoxicity and 0% for women without a history of cardiotoxicity. When comparing clinical characteristics between women with and without CHF, there was no difference in age of cancer diagnosis, cancer type, or exposure to anthracyclines.
    • Risk factors for developing CHF were history of cardiotoxicity before pregnancy, left ventricular systolic dysfunction at first antenatal visit, or receiving cardiac medications.

Based on available evidence about peripartum cardiomyopathy, the International Guideline Harmonization Group assessed that cardiomyopathy surveillance is reasonable before pregnancy or in the first trimester for female survivors of childhood, adolescent, and young adult cancer who are at moderate and high risk because they were treated with anthracyclines or chest radiation therapy.[32]

Mortality Risk After Major Cardiovascular Events

Survivors of childhood cancer represent a population at high risk of mortality after major cardiovascular events. Investigators estimated the cumulative incidence of all-cause and cardiovascular cause–specific mortality among survivors from the CCSS who had experienced a major cardiovascular event and compared them to siblings. They also compared the outcomes from the CCSS cancer survivors with a population-based cohort of racially diverse adults from the Coronary Artery Risk Development in Young Adults (CARDIA) study.[85]

  • Among the 25,658 childhood cancer survivors (median age at diagnosis, 7 years; median age at follow-up or death, 38 years) and 5,051 siblings, 1,780 survivors and 91 siblings experienced a cardiovascular event.
  • The 10-year all-cause mortality rate for survivors was 30% after heart failure, 36% after cardiovascular artery disease, and 29% after stroke. The 10-year all-cause mortality rate for siblings was 14% after heart failure, 14% after coronary artery disease, and 4% after stroke (P < .001 for all survivors).
  • All-cause mortality risks among childhood cancer survivors were increased after heart failure (HR, 7.32), coronary artery disease (HR, 5.54), and stroke (HR, 3.57).
  • Among 5,114 CARDIA participants, 345 had a major event. CARDIA participants were, on average, decades older at events (median age, 57 years vs. 31 years). However, mortality risks were similar, except that all-cause mortality after coronary artery disease was significantly increased among childhood cancer survivors (HR, 1.85).

Heart Transplant After Childhood Cancer

Data about the prevalence and outcomes of survivors with heart failure requiring heart transplant are limited.

  • In a study of solid organ transplants in 13,318 survivors in the CCSS, 62 survivors had end-stage heart failure that warranted heart transplants, 37 of whom received a heart transplant.[86]
  • At 35 years after cancer diagnosis, the cumulative incidence of heart transplant was 0.30%, and the cumulative incidence of being placed on the waiting list or receiving a heart was 0.49%.[86]
  • The 5-year survival rate from heart transplant was 80.6%, which is similar to the outcome in the general population of the same age range.[86]

Knowledge Deficits

While much knowledge has been gained over the past 20 years in better understanding the long-term burden and risk factors for cardiovascular disease among childhood cancer survivors, many areas of inquiry remain, and include the following:

  • Radiation may have both direct and indirect effects on vascular endothelium, contributing to vascular damage beyond the primary radiation field.[87]
  • The long-term effects of lower radiation doses, particularly in the setting of advanced technology that allows tumor targeting from multiple directions and reduces exposure to surrounding normal tissues, remain to be determined.[88]
  • The long-term effects of many newer anticancer agents that are based on molecular targets remain unclear, although some of them are known to have shorter-term cardiac toxicity.[15]
  • The efficacy of cardioprotective strategies, including the use of alternative anthracycline formulations that appear promising in adults, requires further study in children.[42]

Screening, Surveillance, and Counseling

The International Guideline Harmonization Group has worked collaboratively to harmonize evidence-based cardiac surveillance recommendations and have identified knowledge deficits to help guide future studies.[32,71] Risk groups defined by cumulative exposures of anthracycline and chest-directed radiation therapy as well as cardiomyopathy surveillance recommendations are summarized in Table 2.

Consensus regarding evidence about screening, surveillance, and counseling

  • There is no clear evidence (at least through age 50 years or 30–40 years posttreatment) that a plateau in risk occurs after a certain time among survivors exposed to cancer treatments associated with cardiovascular late effects.[89,90] Thus, life-long surveillance is recommended by one group, even if the cost-effectiveness of certain screening strategies remains unclear.[32,91,92,93]
    Table 2. Risk Groups and Cardiomyopathy Surveillance Recommendations for Survivors of Childhood, Adolescent, and Young Adult Cancera
    Risk Group Anthracycline (mg/m2) Chest-Directed Radiation Therapy (Gy) Anthracycline (mg/m2) + Chest-Directed Radiation Therapy (Gy) Is Screening Recommended? At What Interval?
    NA = not applicable.
    a Adapted from Ehrhardt et al.[32]
    High risk ≥250 ≥30 ≥100 and ≥15 Yes 2 years
    Moderate risk 100 to <250 15 to <30 NA Maybe 5 years
    Low risk >0 to <100 >0 to <15 NA No No screening
  • A growing body of literature is beginning to establish the yield from these screening studies, which will help inform future guidelines.[8,94,95,96] In these studies, for example, among adult-aged survivors of childhood cancer, evidence for cardiomyopathy on the basis of echocardiographic changes was found in approximately 6% of at-risk survivors. Overall, in a cohort of more than 1,000 survivors (median age, 32 years), nearly 60% of screened at-risk survivors had some clinically ascertained cardiac abnormality identified.[8]
  • Given the growing evidence that conventional cardiovascular conditions such as hypertension, dyslipidemia, and diabetes substantially increase the risk of more serious cardiovascular disease among survivors, clinicians should carefully consider baseline and follow-up screening and treatment of these comorbid conditions that impact cardiovascular health (see Table 3).[7,56,68,97]
  • There is also emerging evidence that adoption of healthier lifestyle factors may decrease future cardiovascular morbidity in at-risk survivors.[98,99] Thus, similar to the general population, survivors should be counseled about maintaining a healthy weight, participating in regular physical activity, adhering to a heart-healthy diet, and abstaining from smoking.
  • The COG has organized handouts on cardiovascular disease and related topics, including lifestyle choices, written for a lay audience to facilitate counseling and education of survivors. For more information, see the COG Survivorship Guidelines.

Predicting Cardiovascular Disease Risk

  • Attempts to develop more individualized risk prediction for cardiovascular disease may help refine surveillance and counseling in the future.
  • Several groups have collaborated to develop and validate individualized risk calculators for heart failure, ischemic heart disease, and stroke through age 50 years.[33,62,97]
  • Updated models based only on CCSS data have incorporated hypertension, dyslipidemia, and diabetes status across time to further refine prediction.[97]
  • An online risk calculator incorporating these models is available on the CCSS website.

Risk prediction and interventions for cardiovascular diseases

  • Using data from four large, well-annotated childhood cancer survivor cohorts (CCSS, National Wilms Tumor Study Group, the Netherlands, and SJCRH), a heart failure risk calculator based on readily available demographic and treatment characteristics has been created and validated. This calculator may provide more individualized clinical heart failure risk estimation for 5-year survivors of childhood cancer who have recently completed therapy, through age 40 years. Because of the young age of participants at the time of baseline prediction (5-year survival), this estimator is limited in that information on conventional cardiovascular conditions such as hypertension, dyslipidemia, or diabetes could not be incorporated.[33]
  • In another collaborative study, data from the CCSS, Netherlands, and SJCRH were used to develop risk-prediction models for ischemic heart disease and stroke among 5-year survivors of childhood cancer through age 50 years. Risk scores derived from a standard prediction model that included sex, chemotherapy exposure, and radiation therapy exposure identified statistically distinct low-risk, moderate-risk, and high-risk groups. The cumulative incidences at age 50 years among CCSS low-risk groups were less than 5%, compared with approximately 20% for high-risk groups and only 1% for siblings.[62]
  • Traditional cardiovascular risk factors remain important for predicting risk of cardiovascular disease among adult-aged survivors of childhood cancer. This finding was demonstrated by a CCSS investigation that constructed prediction models accounting for cardiotoxic cancer treatment exposures, combined with information on traditional cardiovascular risk factors such as hypertension, dyslipidemia, and diabetes. Risk scores based on demographic, cancer treatment, hypertension, dyslipidemia, and diabetes information showed good performance (area under the receiver operating characteristic curve and concordance statistics ≥0.70) for predicting cardiovascular events in the models applied to the discovery and replication cohorts. The most influential exposures were anthracycline chemotherapy, radiation therapy, diabetes, and hypertension.[97]
  • Physical activity has been shown to be a safe intervention against the high burden of cardiovascular late effects in childhood cancer survivors. A randomized controlled trial investigated the effect of a partially supervised, personalized, 1-year physical activity intervention on cardiovascular health in long-term survivors of childhood cancer.[100] There were 151 childhood cancer survivors randomly assigned (1:1) to either perform more than 2.5 hours of additional intense physical activity per week (intervention group) or continue exercise as usual (control group). A significant and robust reduction of the cardiovascular disease risk score was noted at 6 months and 12 months in the intervention group, compared with the control group. The difference in the reduction of the cardiovascular disease risk z-score of -0.18 (P = .003) at 12 months favored the intervention group.
Table 3. Cardiovascular Late Effectsa,b
Predisposing Therapy Potential Cardiovascular Effects Health Screening
a The Children's Oncology Group (COG) guidelines also cover other conditions that may influence cardiovascular risk, such as obesity and diabetes mellitus/impaired glucose metabolism.
b Adapted from theChildren's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers.
Any anthracycline and/or any radiation exposing the heart Cardiac toxicity (arrhythmia, cardiomyopathy/heart failure, pericardial disease, valve disease, ischemic heart disease) Yearly medical history and physical examination
Electrocardiography at entry into long-term follow-up
Echocardiography at entry into long-term follow-up, periodically repeat based on previous exposures and other risk factors
Radiation exposing the neck and base of skull (especially ≥40 Gy) Carotid and/or subclavian artery disease Yearly medical history and physical examination; consider Doppler ultrasonography 10 years after exposure
Radiation exposing the brain/cranium (especially ≥18 Gy) Cerebrovascular disease (cavernomas, moyamoya, occlusive cerebral vasculopathy, stroke) Yearly medical history and physical examination
Radiation exposing the abdomen Diabetes Diabetes screening every 2 years
Total-body irradiation (usually <14 Gy) Dyslipidemia; diabetes Fasting lipid profile and diabetes screening every 2 years
Heavy metals (carboplatin, cisplatin), and ifosfamide exposure; radiation exposing the kidneys; HSCT; nephrectomy Hypertension (from renal toxicity) Yearly blood pressure test; renal function laboratory studies at entry into long-term follow-up and repeat as clinically indicated
HSCT = hematopoietic stem cell transplant.

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Late Effects of the Central Nervous System

Neurocognitive

Neurocognitive late effects are commonly observed after treatment of malignancies that require central nervous system (CNS)–directed therapies, including the following:

  • Cranial radiation therapy.
  • Systemic therapy with high-dose methotrexate or cytarabine.
  • Intrathecal chemotherapy.
  • Neurosurgical procedures.[1,2]

Children with CNS tumors or acute lymphoblastic leukemia (ALL) are most likely to be affected. Risk factors for the development of neurocognitive late effects include the following:[3,4,5,6,7]

  • Female sex.
  • Younger age at the time of treatment.
  • Tumor location.
  • Treatment with cranial radiation therapy and/or chemotherapeutic agents (systemic or intrathecal).
  • Higher cranial radiation dose.
  • Time since treatment.

Cognitive phenotypes observed in childhood survivors of ALL and CNS tumors may differ from traditional developmental disorders. For example, the phenotype of attention problems in ALL and brain tumor survivors appears to differ from developmental attention-deficit/hyperactivity disorder (ADHD) in that few survivors demonstrate significant hyperactivity/impulsivity, but instead have associated difficulties with processing speed and executive function.[8,9]

A Pediatric Normal Tissue Effects in the Clinic (PENTEC) comprehensive review was performed to develop models to facilitate the identification of dose constraints for radiation-associated CNS morbidities.[10]

  • Models suggest a 5% risk of a subsequent intelligence quotient (IQ) lower than 85 when the following occurs:
    • 10% of the brain is irradiated to 35.7 Gy.
    • 20% of the brain is irradiated to 29.1 Gy.
    • 50% of the brain is irradiated to 22.2 Gy.
    • 100% of the brain is irradiated to 18.1 Gy.
    • Note: All at 2 Gy/fraction and without methotrexate.
  • Methotrexate exposure increased the risk of an IQ score lower than 85, similar to a generalized uniform brain radiation dose of 5.9 Gy. However, a limitation to this analysis was a lack of data about the total methotrexate doses, both intravenous and intrathecal.
  • The model for predicting expected IQ, which also included the effect of dose, age, and methotrexate, suggested that each of these factors has an independent but probably cumulative effect on IQ.

In addition to the direct effects of neurotoxic therapies like cranial radiation, Childhood Cancer Survivor Study (CCSS) investigators observed that chronic health conditions resulting from non-neurotoxic treatment exposures (e.g., thoracic radiation) can adversely impact neurocognitive function presumably mediated by chronic cardiopulmonary and endocrine dysfunction.[11] In addition, some sequelae of neurotoxic therapy (e.g., severe hearing loss) have been associated with neurocognitive deficits independent of the neurotoxic treatment received.[12]

A related investigation from the CCSS evaluated longitudinal associations between physical activity and neurocognitive problems in adult survivors of childhood cancer.[13]

  • Survivors were less likely than their siblings to report consistent physical activity (28.1% vs. 33.6%).
  • Survivors who reported more consistent physical activity had fewer neurocognitive problems and larger improvements in cognitive concerns years after treatment.
  • Body mass index (BMI) and severe chronic health conditions partially mediated the physical activity–neurocognitive associations, but the mediation effects were small.

A subsequent systematic review and meta-analysis compared the effects of physical activity or exercise interventions on cognitive function among individuals diagnosed with cancer (aged 0–19 years) with that of controls. Twenty-two unique studies (16 randomized controlled trials) were found with data on 12,767 individuals.[14] The median age at the start of the study was 12 years (interquartile range [IQR], 11–14 years), the median time from the end of cancer treatment was 2.5 years (IQR, 1.1–3.0 years), and the median intervention period was 12 weeks (IQR, 10–24 weeks).

  • Compared with controls, there was moderate-quality evidence that physical activity and exercise improved cognitive performance measures and patient-reported measures of cognitive function in cancer survivors.

Childhood cancer survivors may be at risk for cognitive decline throughout their lives (even if not present in the first 10 years after therapy). In a study of 2,375 adult survivors of childhood ALL, Hodgkin lymphoma, or CNS tumors (mean age at evaluation, 31.8 years) and their sibling controls, new onset memory impairment emerged more often in survivors, decades after cancer diagnosis and treatment.[15]

  • Compared with siblings, a higher proportion of survivors with no impairment in memory at baseline had new-onset memory impairment at follow-up, as follows:
    • Sibling proportion, 7.8%.
    • ALL survivors treated with chemotherapy only, 14.0%.
    • ALL survivors treated with cranial radiation therapy, 25.8%.
    • CNS tumor survivors, 34.7%.
    • Hodgkin lymphoma survivors, 16.6%.
  • Factors associated with new-onset memory impairment included cranial radiation in survivors of CNS tumor (relative risk [RR], 1.97) and dose of 8,000 mg/m2 or more of alkylator chemotherapy in survivors of ALL treated without cranial radiation therapy (RR, 2.80).
  • Neurological conditions mediated the impact of cranial radiation therapy on new-onset memory impairment in survivors of CNS tumors.
  • Smoking, obesity, low education attainment, and low physical activity were associated with an elevated risk of new onset-memory impairment.

Neurocognitive outcomes in brain tumor survivors

Long-term cognitive effects caused by illness and associated treatments are well-established morbidities in survivors of childhood and adolescent brain tumors. Risk factors for adverse neurocognitive effects in this group include the following:

  • Cranial radiation therapy.
    • Cranial radiation therapy has been associated with the highest risk of long-term cognitive morbidity, particularly in younger children.[3,4]
    • There is an established dose-response relationship, with patients who receive higher-dose cranial radiation therapy consistently performing more poorly on intellectual measures.[3,4]
    • Radiation dose to specific regions of the brain, including the temporal lobes and hippocampi, have been shown to significantly impact longitudinal IQ scores and academic achievement scores among children treated with craniospinal irradiation for medulloblastoma.[16]
  • Tumor site.[3]
  • Shunted hydrocephalus.[17,18]
  • Postsurgical cerebellar mutism.[19]
  • Auditory difficulties, including sensorineural hearing loss.[12,17]
  • History of stroke.[20]
  • Seizures.[3,21]
  • Socioeconomic status (SES).[22]

The negative impact of radiation treatment has been characterized by changes in IQ scores, which have been noted to drop about 2 to 5 years after diagnosis.[23,24,25]

  • The decline continues 5 to 10 years afterward, although less is known about potential stabilization or further decline of IQ scores several decades after diagnosis.[23,25]
  • The decline in IQ scores over time typically reflects the child's failure to acquire new abilities or information at a rate similar to that of his or her peers, rather than a progressive loss of skills and knowledge.[26]
  • Affected children also may experience deficits in other cognitive areas, including academic domains (reading and math) and problems with attention, processing speed, memory, and visual or perceptual motor skills.[27]
  • Changes in cognitive functioning may be partially explained by radiation-induced reduction of normal-appearing white matter volume or integrity of white matter pathways, as evaluated through magnetic resonance imaging (MRI).[28,29]
    • Reduced white matter integrity has been directly linked to slowed cognitive processing speed in survivors of brain tumors,[30] while greater white matter volume has been associated with better working memory, particularly in females.[29]
    • Data from contemporary protocols show that using lower doses of cranial radiation, proton beam radiation, and more targeted treatment volumes appears to reduce the severity of neurocognitive effects of therapy.[3,18]

Evidence (predictors of cognitive decline among survivors of CNS tumors):

Longitudinal cohort studies have provided insight into the trajectory and predictors of cognitive decline among survivors of CNS tumors.

  1. A multisite, prospective, longitudinal trial evaluated predictors of cognitive performance among 139 infants with brain tumors who were treated with chemotherapy, with or without focal proton or photon radiation therapy.[31]
    • IQ, parent-reported working memory, and parent-reported adaptive functioning were worse than normative expectations at baseline, with younger age and lower SES representing predictive factors.
    • IQ remained stable over time, whereas parent-reported attention and executive dysfunction increased.
    • Cognitive outcomes did not differ by treatment exposure (chemotherapy only vs. chemotherapy with radiation therapy).
    • Changes in cognitive function were associated with supratentorial tumor location and cerebrospinal fluid diversion.
  2. St. Jude Children's Research Hospital (SJCRH) studied 78 children younger than 20 years (mean, 9.7 years) diagnosed with a low-grade glioma.[32]
    • Cognitive decline after 54 Gy of conformal cranial radiation therapy was noted (see Figure 5).
    • Age at time of cranial irradiation was more important than was cranial radiation dose in predicting cognitive decline, with children younger than 5 years estimated to experience the greatest cognitive decline.

      Graph shows modeled IQ scores after conformal radiation therapy, by age measured in years, and time measured in months, after the start of CRT for pediatric low-grade glioma.
      Figure 5. Modeled intelligence quotient (IQ) scores after conformal radiation therapy (CRT) by age for pediatric low-grade glioma. Age is measured in years, and time is measured in months after the start of CRT. Thomas E. Merchant, Heather M. Conklin, Shengjie Wu, Robert H. Lustig, and Xiaoping Xiong, Late Effects of Conformal Radiation Therapy for Pediatric Patients With Low-Grade Glioma: Prospective Evaluation of Cognitive, Endocrine, and Hearing Deficits, Journal of Clinical Oncology, volume 27, issue 22, pages 3691-3697. Reprinted with permission. © (2009) American Society of Clinical Oncology. All rights reserved.

  3. In a study of 51 children with low-grade gliomas and low-grade glioneural tumors diagnosed within the first year of life, the following was reported:[33]
    • Mean IQ score was 75.5; 75% of the children had IQ scores lower than 85.
    • Predictors of low IQ included a supratentorial location of the primary tumor and treatment with more chemotherapy regimens but not radiation use.
    • The child's ability to complete age-appropriate tasks was as affected as IQ scores.
  4. A study of 126 medulloblastoma survivors treated with 23.4 Gy or 36 Gy to 39.6 Gy of craniospinal radiation (with a conformal boost dose of 55.8 Gy to the primary tumor bed) assessed processing speed, attention, and memory performance.[34]
    • Processing speed scores declined significantly over time, while less decline was observed in attention and memory performance. Higher doses of radiation and younger age at diagnosis predicted slower processing speed over time.
    • Studies of working memory and academic achievement in patients enrolled on the same medulloblastoma trial (SJCRH SJMB03 [NCT00085202]) indicated that performance was largely within the age-expected range up to 5 years postdiagnosis,[35,36] although in both studies, posterior fossa syndrome, higher cranial radiation dose, and younger age at diagnosis predicted worse performance over time.
    • Serious hearing loss was associated with intellectual and academic decline over time.[36]
  5. In a prospective study of 178 children with medulloblastoma, 60 (34%) developed posterior fossa syndrome. Of these patients, 40 (23%) developed complete mutism and 20 (11%) developed diminished speech.[37]
    • All children with posterior fossa syndrome had severe ataxia, and 42.5% of patients with posterior fossa syndrome and complete mutism had movement disorders.
    • Independent risk factors for posterior fossa syndrome included younger age and surgery in a low-volume surgery center. Risk was lower among children with sonic hedgehog (SHH) tumors.
    • Speech and gait returned in children with posterior fossa syndrome and complete mutism at a median of 2.3 and 0.7 months, respectively. Speech and gait returned in children with posterior fossa syndrome and diminished speech at a median of 2.1 and 1.5 months, respectively. However, with 12 months of follow-up, 12 of 27 children (44.4%) with posterior fossa syndrome and complete mutism were nonambulatory at 1 year.
    • The presence of a movement disorder or high ataxia score was associated with delayed speech recovery, whereas older age and high ataxia score were associated with delayed gait return.
    • Symptoms improved in all children, but no child with posterior fossa syndrome had a normal neurological examination at a median of 23 months after surgery.
  6. A prospective study compared 36 pediatric patients with medulloblastoma who experienced posterior fossa syndrome with 36 patients with medulloblastoma who did not experience posterior fossa syndrome but were matched on treatment and age at diagnosis.[37,38]
    • The posterior fossa syndrome group demonstrated lower mean scores at 1, 3, and 5 years postdiagnosis on general intellectual ability, processing speed, working memory, and spatial relations compared with the non–posterior fossa syndrome group.
    • The group who experienced posterior fossa syndrome showed little recovery over time and further decline over time in some domains (attention and working memory), compared with the non–posterior fossa syndrome group.
  7. Canadian investigators evaluated the impact of radiation (dose and boost volume) and neurological complications on patterns of intellectual functioning in a cohort of 113 medulloblastoma survivors (mean age at diagnosis, 7.5 years; mean time from diagnosis to last assessment, 6 years).[4]
    • Survivors treated with reduced-dose craniospinal radiation therapy plus tumor bed boost showed stable intellectual functioning.
    • Neurological complications, such as hydrocephalus requiring cerebrospinal fluid diversion and mutism, and treatment with higher doses and larger boost volumes of radiation resulted in intellectual declines with distinctive trajectories.
  8. Studies are beginning to examine cognitive outcomes in histologically distinct subtypes of brain tumors.
    • Data from a sample of 121 medulloblastoma patients demonstrated variation in cognitive outcomes by four distinct molecular subgroups and differences in patterns of change over time.[39]
    • Future research is required to establish if neurocognitive outcomes vary across biologically distinct subtypes of childhood brain tumors.
  9. SES has been shown to predict long-term cognitive outcomes in brain tumor survivors. In a prospective, longitudinal, phase II study of 248 children who were treated with conformal radiation therapy (54–59.4 Gy) for ependymoma, low-grade glioma, or craniopharyngioma, patients were monitored serially with cognitive assessment for 10 years.[22]
    • At preradiation therapy baseline, significant associations were seen between SES and IQ, reading and math scores, sustained attention, and adaptive function. Higher SES was associated with better performance (P < .005).
    • SES predicted change over time in IQ and reading and math scores. Higher SES was associated with less decline (P < .001).
    • These results suggest that higher SES is a protective factor for cognitive late effects.

Evidence (predictors of cognitive decline among long-term survivors of CNS tumors):

Although adverse neurocognitive outcomes observed 5 to 10 years after treatment are presumed to be pervasive, and potentially worsen over time, few empirical data are available regarding the neurocognitive functioning in very long-term survivors of CNS tumors.

  1. A longitudinal study evaluated the relationship of hippocampal dose and short-term memory decline in 80 children and adolescents with low-grade gliomas (median age, 9.5 years at treatment) who received 54 Gy of radiation therapy.[40]
    • At a median neurocognitive follow-up of 9.8 years, higher hippocampal dose (volume receiving 40 Gy) was associated with a greater decline in delayed recall.
  2. Among adult survivors participating in the CCSS, CNS tumor survivors (n = 802) self-reported significantly more problems with attention/processing speed, memory, emotional control, and organization than did survivors of non-CNS malignancies (n = 5,937) and sibling controls (n = 382).[41]
  3. Another CCSS study evaluating patterns of late mortality and morbidity in 2,821 adult survivors of CNS tumors reported impairment on measures of attention/processing speed (42.9%–73.3%) and memory (14.3%–37.4%), with differences observed by diagnosis and cranial radiation dose.[42]
  4. A study of 224 adult survivors of pediatric brain tumors participating in the St. Jude Life (SJLIFE) cohort study revealed that 20% to 30% of the survivors demonstrated severe neurocognitive impairment (defined as at least two standard deviations below normative mean) on clinical assessments of intelligence, memory, and executive function (e.g., planning, organization, and flexibility).[3]
    • Among adults in the general population, the expected impairment rate at this threshold is 2%.
    • Survivors who received whole-brain cranial irradiation were 1.5 to 3 times more likely to have severe neurocognitive impairment than were survivors who did not receive any cranial irradiation.
    • Hydrocephalus with shunt placement and seizures were also associated with increased risk of impairment.
  5. In the CCSS, investigators compared long-term neuropsychological and SES outcomes of 181 adult survivors of pediatric low-grade gliomas with the outcomes of an age-matched and sex-matched sibling comparison group.[43]
    • Survivors who were treated with surgery and radiation therapy (median age at diagnosis, 7 years; median age at assessment, 41 years) scored lower on estimated IQ than did survivors who were treated with surgery only, who scored lower than siblings (surgery and radiation therapy, 93.9; surgery only, 101.2; siblings, 108.5; all P values < .0001).
    • Younger age at diagnosis was predictive of low scores for all neuropsychological outcomes except for attention/processing speed.
    • Survivors who were treated with surgery and radiation therapy had more-than-twofold–lower occupation scores, income, and education than did survivors who were treated with surgery only.
  6. In a retrospective review of 528 brain tumor survivors diagnosed between 2000 and 2015, the prevalence of a clinical diagnosis of ADHD was 13.1%.[44]
    • Of the survivors, 12.1% used medications for ADHD, and 19.9% of survivors had symptoms of ADHD without a clinical diagnosis.
    • ADHD diagnosis was associated with younger age at tumor diagnosis and supratentorial tumor location, but not with sex, tumor type, or treatment type.

The neurocognitive consequences of CNS disease and treatment may have a considerable impact on functional outcomes for brain tumor survivors.

  • In childhood and adolescence, neurocognitive deficits have been associated with poor social adjustment, including problems with peer relations, social withdrawal, and reduced social skills.[45,46]
  • CNS tumor survivors are more likely to need special education services than are survivors of other malignancies.[47]
  • Adult CNS tumor survivors are less likely to live independently, marry, and graduate from college than are survivors of other malignancies and siblings.[48]

Cognitive outcomes after proton radiation therapy

Data are emerging regarding cognitive outcomes after proton radiation to the CNS.[49,50,51] However, these studies have been limited by retrospective analysis of cognitive outcomes among relatively small clinically heterogenous pediatric brain tumor cohorts and the use of historically treated photon patients or population standards as comparison groups.

  • In studies largely describing IQ changes during early follow-up (<5 years from radiation), results demonstrate lack of difference in slopes of IQ change among photon-treated and proton-treated patients [49] and significant declines in cognitive processing speed among patients treated with proton radiation.[50]
  • One study compared the intellectual trajectories between pediatric patients with medulloblastoma who were treated with proton and photon radiation therapy (4.3-year mean follow-up after median 23.4-Gy craniospinal irradiation dose). Notably, boost dose and margins were significantly different between the two groups.[51]
    • Children treated with proton radiation therapy exhibited superior long-term outcomes in global IQ, perceptual reasoning, and working memory compared with children who were treated with photon radiation therapy.
    • The photon radiation therapy group exhibited a significant decline in global IQ, working memory, and processing speed.
    • The proton radiation therapy group exhibited stable scores over time in all domains, except for processing speed.

Considering the relatively brief follow-up time from radiation, longitudinal follow-up is important to determine whether proton radiation provides a clinically meaningful benefit in sparing cognitive function compared with photon radiation. In addition, more targeted radiation treatment volumes with photons may diminish potential differences.

Neurocognitive outcomes in acute lymphoblastic leukemia (ALL) survivors

To minimize the risk of late cognitive sequelae, contemporary therapy for ALL uses a risk-stratified approach that reserves cranial irradiation for children who are considered at high risk of CNS relapse.

ALL and cranial radiation

In survivors of ALL, cranial radiation therapy may result in clinical and radiographic neurological late sequelae, including the following:

  • Clinical leukoencephalopathy. Clinical leukoencephalopathy characterized by fluctuating encephalopathy, stroke-like symptoms, spasticity, ataxia, dysarthria, dysphagia, hemiparesis, and seizures is uncommon after contemporary ALL therapy. Neuroimaging frequently demonstrates white matter abnormalities among survivors treated with cranial irradiation and/or high-dose methotrexate.
    • Radiographic leukoencephalopathy has been reported in up to 80% of children on some treatment regimens.
    • Higher doses and more courses of intravenous methotrexate have been reported to increase risk of leukoencephalopathy.[52]
    • In many patients, white matter anomalies are transient and decrease in prevalence, extent, and intensity with longer elapsed time from completion of therapy.[52]
    • Leukoencephalopathy results in smaller white matter volumes that have been correlated with cognitive deficits.[52]
    • Although these abnormalities are mild among the irradiated patients (overall IQ decline of approximately 10 points), those who have received higher doses at a young age may have significant learning difficulties.[53,54]
  • Neurocognitive deficits. Deficits in neurocognitive functions such as visual-motor integration, processing speed, attention, and short-term memory are reported in children treated with 18 Gy to 24 Gy.[53,55,56]
    • Females and children treated at a younger age are more vulnerable to the adverse impact of cranial radiation on the developing brain.[5]
    • The decline in intellectual functioning appears to be progressive, showing more impairment of cognitive function with increasing time since radiation therapy.[5,6]
    • Limited studies suggest that long-term survivors of childhood ALL treated with cranial irradiation are at risk of progressive decline consistent with early-onset mild cognitive impairment; this risk is most prominent among those treated with cranial radiation doses of 24 Gy.[57,58]

ALL and chemotherapy-only CNS therapy

Because of its penetrance into the CNS, systemic methotrexate has been used in a variety of low-dose and high-dose regimens for leukemia CNS prophylaxis.

  • Systemic methotrexate in high doses with or without radiation therapy can lead to an infrequent but well-described leukoencephalopathy, which has been linked to neurocognitive impairment.[52]
  • When neurocognitive outcomes after radiation therapy and chemotherapy-only regimens are directly compared, the evidence suggests a better outcome for those treated with chemotherapy alone, although some studies show no significant difference.[59,60]
  • In a longitudinal analysis of 210 childhood ALL survivors, the development of acute leukoencephalopathy during chemotherapy-only CNS therapy predicted higher risks of developing long-term neurobehavioral problems (e.g., deficits in organization and task initiation [components of executive function]) and reduced white matter integrity in frontal brain regions.[61]
  • Compared with cranial irradiation, chemotherapy-only CNS-directed treatment produces neurocognitive deficits involving processes of attention, speed of information processing, memory, verbal comprehension, visual-spatial skills, visual-motor functioning, and executive functioning. Global intellectual function is typically preserved.[55,59,62,63,64]
  • Few longitudinal studies evaluating long-term neurocognitive outcome report adequate data for a decline in global IQ after treatment with chemotherapy alone.[62]
  • The academic achievement of ALL survivors in the long term seems to be generally average for reading and spelling, with deficits mainly affecting arithmetic performance.[59,65]
  • Risk factors for poor neurocognitive outcome after chemotherapy-only CNS-directed treatment are younger age and female sex.[64,66]
  • Reduced cognitive status has been observed in association with reduced integrity in neuroanatomical regions essential in memory formation (e.g., reduced hippocampal volume with increased activation and thinner parietal cortices).[61]
  • The long-term impact of these prevalent neurocognitive and neuroimaging abnormalities on functional status in aging adults treated for childhood ALL, particularly those treated with contemporary approaches using chemotherapy alone, remains an active area of research.
  • Research in childhood ALL survivors treated with chemotherapy alone suggests that genetic predisposition may modulate risk of developing neurocognitive late effects. It also provides insights into potential mechanisms underlying neurocognitive deficits.[67,68]

Evidence (neurocognitive functioning in large pediatric cancer survivor cohorts):

  1. CCSS investigators identified sex-specific associations between treatment and chronic health conditions with neurocognitive impairment among 1,207 survivors of ALL (mean age, 30.6 years) who were treated with chemotherapy only.[7]
    • Both male and female survivors reported increased prevalence of impaired task efficiency (attention and processing speed; adjusted odds ratio [OR], 1.89 for males; OR, 1.50 for females) and impaired memory (OR, 1.89 for males; OR, 1.96 for females) compared with 2,273 same-sex siblings.
    • Among male survivors, impaired task efficiency was associated with grades 2 to 4 neurological conditions (OR, 4.33) and pulmonary conditions (OR, 4.99). Impaired memory was associated with increased cumulative dose of intrathecal methotrexate (OR, 1.68) and exposure to dexamethasone (OR, 2.44).
    • In female survivors, grades 2 to 4 endocrine conditions were associated with higher risk of impaired task efficiency (OR, 2.19) and memory (OR, 2.26).
  2. The CCSS examined parent-reported cognitive, behavior, and learning problems from 1,560 adolescent survivors of childhood ALL who were treated with chemotherapy alone between 1970 and 1999.[69]
    • Survivors treated with cranial irradiation had significantly higher frequency of problems in anxiety-depression, inattention-hyperactivity, and social withdrawal than did patients who were not treated with cranial irradiation.
    • Compared with siblings, survivors treated with chemotherapy only were more likely to demonstrate headstrong behavior (19% of survivors vs. 14% of siblings, P = .010), inattention-hyperactivity (19% vs. 14%, P < .0001), social withdrawal (18% vs. 12%, P = .002), and had higher rates of learning problems (28% vs. 14%, P < .0001).
    • In multivariable models among survivors, increased cumulative dose of intravenous methotrexate (i.e., >4.3 g/m2) conferred increased risk of inattention-hyperactivity (RR, 1.53).
    • Adolescent survivors with cognitive or behavior problems and those with learning problems were less likely to graduate from college as young adults than adolescent survivors without cognitive or behavior problems.
    • Inattention and hyperactivity problems were associated with the highest risk of special education placement during adolescence. Participation in special education during adolescence did not improve adult educational attainment.
  3. The SJCRH TOTAL XVI (NCT00549848) trial evaluated whether a higher dose of pegaspargase and early intensification of triple intrathecal therapy (ITT; methotrexate, hydrocortisone, and cytarabine) would improve systemic and CNS control in children with newly diagnosed ALL. Intensified ITT was defined as more than 21 cumulative doses for patients with low-risk ALL (70 of 194) and more than 27 doses for those with standard- and high-risk ALL (81 of 206). Neurocognitive testing was completed at the end of therapy.[70]
    • The overall group had below age-based norms on measures of global intelligence (P < .0001), attention (P = .0051), working memory (P = .0001), processing speed (P = .0002), fine motor speed (P = .0001), and math skills (P = .0087). Caregiver ratings of patient functioning showed elevated risks of problems in attention (P = .0173), executive function (P = .0001), and adaptive skills (P = .0001).
    • In the low-risk group, there were no significant differences between patients treated with and without intensified ITT.
    • Patients with standard- and high-risk ALL who were treated with intensified ITT had poorer working memory (P = .0328) and fine motor speed (P = .0403), and elevated ratings of inattention (P = .0189) and executive dysfunction (P = .0245). Females in this risk group treated with intensified ITT had lower working memory scores.
  4. In the SJCRH Total XV (NCT00137111) trial, which omitted prophylactic cranial irradiation, comprehensive cognitive testing of 243 participants at week 120 revealed the following:[71]
    • A higher risk of below-average performance on a measure of sustained attention but not on measures of intellectual functioning, academic skills, or memory.
    • The risk of cognitive deficits correlated with treatment intensity but not with age at diagnosis or sex.
    • Prolonged follow-up (average, 7.7 years from diagnosis) of this cohort demonstrated that intelligence was within normal limits compared with population expectations, but measures of executive function, processing speed, and memory were less than population means.
    • Higher plasma methotrexate was associated with executive dysfunction, thicker cerebral cortex, and higher activity in frontal brain regions on functional MRI.
  5. In a large prospective study of neurocognitive outcomes in children with newly diagnosed ALL, 555 children were randomly assigned to receive CNS-directed therapy according to risk group.[72]
    1. The low-risk group was randomly assigned to receive either intrathecal methotrexate or high-dose methotrexate.
    2. The high-risk group was randomly assigned to receive either high-dose methotrexate or 24 Gy of cranial radiation therapy.
    • A significant reduction in IQ scores (4–7 points) was observed in all patient groups when compared with controls, regardless of the CNS treatment delivered.
    • Children younger than 5 years at diagnosis were more likely to have IQs below 80 at 3 years posttherapy than were children older than 5 years at diagnosis, irrespective of treatment allocation, suggesting that younger children are more vulnerable to treatment-related neurological toxic effects.
  6. Persistent cognitive deficits and progressive intellectual decline have been observed in cohorts of adults treated for ALL during childhood and associated with reduced educational attainment and unemployment.[5,54,58] The results of a study of more than 500 adult survivors of childhood ALL (average, 26 years postdiagnosis) showed the following:[54]
    • Survivors demonstrated increased rates of impairment across all neurocognitive domains (ranging from 28.6%–58.9% for each domain).
    • Rate of severe impairment increased as a function of cranial radiation dose and was common among survivors treated with lower doses of cranial irradiation and chemotherapy only.
    • Impairment in executive function skills increased with time since diagnosis in a cranial radiation dose-dependent manner; impairment in intellect, academics, and memory progressively increased with younger age at treatment in a cranial radiation dose-dependent manner; and neurocognitive impairment was related to functional outcomes as adults, including reduced likelihood of college graduation and full-time employment.

ALL and steroid therapy

The type of steroid used for ALL systemic treatment may affect cognitive functioning.

  • In a study that involved long-term neurocognitive testing (mean follow-up, 9.8 years) of 92 children with a history of standard-risk ALL who had received either dexamethasone or prednisone during treatment, no meaningful differences in mean neurocognitive and academic performance scores were observed.[73]
  • In contrast, in a study of 567 adult survivors of childhood leukemia (mean age, 33 years; mean time since diagnosis, 26 years), the following was reported:[54]
    • Dexamethasone exposure was associated with increased risk of impairment in attention (RR, 2.12; 95% confidence interval [CI], 1.11–4.03) and executive function (RR, 2.42; 95% CI, 1.20–4.91), independent of methotrexate exposure.
    • Intrathecal hydrocortisone also increased risk of attention problems (RR, 1.24; 95% CI, 1.05–1.46).

Other cancers

Neurocognitive abnormalities have been reported in other groups of cancer survivors. A study of adult survivors of childhood non-CNS cancers (including ALL, n = 5,937) reported the following:[56]

  • 13% to 21% of survivors reported impairment in task efficiency, organization, memory, or emotional regulation. This rate of impairment was approximately 50% higher than that reported in the sibling comparison group.
  • Factors such as diagnosis before age 6 years, female sex, cranial radiation therapy, and hearing impediment were associated with impairment.

Emerging data suggest that the development of chronic health conditions in adulthood may contribute to cognitive deficits in long-term survivors of non-CNS cancers.

An SJLIFE cohort study evaluated whether children who experienced CNS injury were at higher risk of neurocognitive impairment associated with subsequent late-onset chronic health conditions. A total of 2,859 survivors who were aged 18 years or older and at least 10 years from diagnosis completed a neurocognitive battery and clinical examination. Of these patients, 1,598 had received CNS-directed therapy, including cranial radiation, intrathecal methotrexate, or neurosurgery.[74]

  • CNS-treated survivors performed worse than non–CNS-treated survivors on all neurocognitive tests, and they were more likely to have global neurocognitive impairment (46.9% vs. 35.3%).
  • A dose-response association was observed between severity/burden score of chronic health conditions and global neurocognitive impairment only among CNS-treated survivors (high OR, 2.24; 95% CI, 1.42–3.53; very high OR, 4.07; 95% CI, 2.30–7.17).
  • Cardiovascular and pulmonary conditions were associated with cognitive outcomes (processing speed, executive function, and memory impairment) only in CNS-treated survivors with neurological conditions.

Neurocognitive abnormalities have been reported for the following cancers:

  • Acute myeloid leukemia (AML). CCSS investigators compared the neurocognitive and psychosocial outcomes of 482 survivors (median age, 30 years) with those of 3,190 sibling controls (median age, 32 years).[75]
    • Compared with siblings, AML survivors were more likely to report impairment in overall emotional (RR, 2.19; 95% CI, 1.51–3.18), neurocognitive (RR, 2.03; 95% CI, 1.47–2.79), and physical quality of life (RR, 2.71; 95% CI, 1.61–4.56) outcomes.
    • Survivors were also at increased risk of psychosocial deficits, including lower educational attainment (RR, 1.15; 95% CI, 1.03–1.30), unemployment (RR, 1.41; 95% CI, 1.16–1.71), and lower income (RR, 1.39; 95% CI, 1.17–1.65).
    • Outcomes were not statistically different between survivors who were treated with transplant and survivors who were treated with intensive chemotherapy alone.
  • Osteosarcoma. In a study evaluating neurocognitive function among 80 long-term survivors of osteosarcoma (mean time since diagnosis, 24.7 years), survivors demonstrated lower mean scores in reading skills, attention, memory, and processing speed than did community controls.[76]
    • The presence of cardiac, pulmonary, and endocrine conditions were significantly associated with worse performance on measures of memory and processing speed.
  • Soft tissue sarcoma. SJLIFE study investigators evaluated neurocognitive function and health status through objective clinical assessments in 150 survivors of childhood soft tissue sarcoma (median age, 33 years; median time from diagnosis, 24 years).[77]
    • Compared with community and population controls, survivors demonstrated lower measures of verbal reasoning, mathematics, and long-term memory.
    • Cumulative anthracycline exposure (per 100 mg/m2) was found to be associated with poorer verbal reasoning, reading, and patient-reported vitality.
    • Neurological and neurosensory chronic conditions were associated with poorer mathematics scores and hearing impairment.
    • Better cognitive performance was associated with higher social attainment.
  • Wilms tumor. SJLIFE study investigators examined the prevalence and predictors of neurocognitive outcomes, social attainment, emotional distress, and health-related quality of life in long-term survivors of pediatric Wilms tumor (n = 158; median time since diagnosis, 29 years; median age, 33 years) and compared the results to community controls.[78]
    • Long-term Wilms tumor survivors demonstrated lower neurocognitive function, including verbal reasoning, academics, attention, memory, and executive function, than did controls.
    • Wilms tumor survivors were less likely to graduate from college (OR, 2.23) and had more moderate-to-severe neurological conditions than did controls (18.4% vs. 8.2%; P < .001).
  • Retinoblastoma. Serial assessment of cognitive and adaptive functioning in a group of retinoblastoma survivors younger than 6 years revealed declines in developmental functioning over time, with the most pronounced declines observed in patients with 13q deletions.[79]
    • Further longitudinal follow-up of this cohort identified improvement in adaptive functioning in all treatment groups and in cognitive function in survivors who were treated with enucleation alone from the age of 5 years to the age of 10 years.[80]
    • At age 10 years, overall functioning was generally within the average range, although estimated IQ was significantly below the normative mean for children who were treated with enucleation alone.[80]

    A study of very long-term adult survivors, who were on average 33 years postdiagnosis, demonstrated largely average cognitive functioning across domains of intelligence, memory, attention, and executive function.[81]

  • Lymphoma. Survivors of lymphoma have not historically been considered at risk of developing neurocognitive late effects.
    • However, one report observed that more than two-thirds of survivors of childhood non-Hodgkin lymphoma experienced at least mild neurocognitive impairment, including severe deficits in executive function (13%), attention (9%), and memory (4%).[82]
    • Similarly, in a study of 62 adult survivors of childhood Hodgkin lymphoma, survivors demonstrated worse performance on measures of sustained attention, short- and long-term memory, and cognitive fluency when compared with national normative data.[83] Importantly, measures of cardiac and pulmonary function were also associated with neurocognitive impairment in this group of survivors.
  • Neuroblastoma. CCSS investigators compared cognitive outcomes among 837 survivors of neuroblastoma (median age, 1 year at diagnosis; median attained age, 25 years) and a sibling cohort (median attained age, 23 years) using the CCSS Neurocognitive Questionnaire (NCQ).[84]
    • Survivors had a 50% higher risk of impairment with attention/processing speed and emotional regulation.
    • The risk of neurocognitive impairments was higher among survivors with chronic health conditions.
    • Survivors were also less likely to attain adult milestones, such as living independently.

Hematopoietic stem cell transplant (HSCT)

Cognitive and academic consequences of HSCT in children have also been evaluated and include, but are not limited to, the following:

  • A survey study evaluated late neurocognitive outcomes among 199 survivors of HSCT (HSCT at age <21 years; median follow-up from HSCT, 27.6 years).[85]
    • As assessed by the CCSS NCQ, 18.9% to 32.5% of survivors reported impairments in task efficiency, memory, emotional regulation, or organization, compared with the expected rate of 10% (general population).
    • Quality of life, as assessed by Neuro-Quality of Life Cognitive Function Short Form (Neuro-QoL), among survivors (average T score, 49.6) was comparable to that of the normative population (50).
    • Independent risk factors for impaired Neuro-QoL (T score <40) included hearing issues (OR, 4.7; 95% CI, 1.96–12.6), history of stroke or seizure (OR, 4.46; 95% CI, 1.44–13.8), and sleep disturbances (OR, 6.96; 95% CI, 2.53–19.1).
  • SJCRH investigators examined the influence of age and conditioning with total-body irradiation (TBI) on the trajectory of cognitive function after HSCT. Among 315 patients who completed a baseline assessment, 183 were alive at 1 year after HSCT and completed additional assessments at 1, 3, and 5 years.[86]
    • At 5 years after HSCT, younger patients (aged <3 years at baseline) who received TBI demonstrated a significantly lower IQ than those who did not receive TBI.
    • Longitudinal analyses demonstrated a significant impact of age and TBI over time with declines in cognitive functioning during the first year among the youngest patients and recovery of functioning in subsequent years among patients who did not receive TBI.
    • Young patients who received TBI failed to recover the losses experienced during the first year after HSCT, demonstrating stability in their functioning, but at a lower level.

Neurological Sequelae

Risk of neurological complications may be predisposed by the following:

  • Tumor location.
  • Neurosurgical procedures.
  • Cranial radiation therapy.
  • Spinal radiation therapy.
  • Specific neurotoxic chemotherapeutic agents.

In children with CNS tumors, mass effect, tumor infiltration, and increased intracranial pressure may result in motor or sensory deficits, cerebellar dysfunction, and secondary effects such as seizures and cerebrovascular complications.[87]

Numerous reports describe abnormalities of CNS integrity and function, but such studies are typically limited by small sample size, cohort selection and participation bias, cross-sectional ascertainment of outcomes, and variable time of assessment from treatment exposures. In contrast, relatively few studies comprehensively or systematically ascertain outcomes related to peripheral nervous system function.

CNS tumor survivors remain at higher risk of new-onset adverse neurological events across their lifetimes than siblings. No plateau has been reached for new adverse sequelae, even 30 years from diagnosis, according to a longitudinal study of 1,876 5-year survivors of CNS tumors from the CCSS. The median time from diagnosis was 23 years, and the median age of the patients studied was 30.3 years.[88]

  • Cranial radiation, stroke, tumor recurrence, and development of meningioma were independently associated with late-onset neurological sequelae (seizures, focal neurological dysfunction, and neurosensory abnormalities).
  • This finding supports the need to monitor these patients carefully with continued neurological follow-up within or in close association with a multidisciplinary cancer survivor clinic.

Neurological complications that may occur in survivors of childhood cancer include the following:

Seizures

The development of seizures may occur secondary to tumor mass effect within the CNS and/or from neurotoxic CNS-directed therapies.

  • In 1,876 5-year survivors of CNS tumors from the CCSS, the incidence of seizures increased from 27% in survivors 5 years from diagnosis to 41% in survivors 30 years from diagnosis.[88]
    • Late-onset seizures were associated with frontal lobe radiation of 50 Gy (hazard ratio [HR], 1.8) and temporal lobe radiation in a dose-dependent fashion (HR, 1.9 for 1–49 Gy; HR, 2.2 for >50 Gy).
    • Other risk factors associated with late-onset seizures included recurrence (HR, 2.3), development of meningioma (HR, 2.6), and history of stroke (HR, 2.0).
    • The risk of seizures was elevated for survivors compared with siblings (HR, 12.7).
  • Among survivors of childhood leukemia in the CCSS (N = 4,151; 64.5% treated with cranial irradiation), 6.1% reported the development of a seizure disorder, and seizures occurred more than 5 years after diagnosis in 51% of these patients.[89]
  • An SJLIFE study evaluated the impact of seizure-related factors on neurocognitive, health-related quality of life (HRQOL), and social outcomes in 2,022 childhood cancer survivors (median age, 31.5 years; median time from diagnosis, 23.6 years).[90]
    • Seizures were identified in 232 survivors (11.5%; 29.9% of survivors with CNS tumors and 9.0% of survivors without CNS tumors).
    • Among CNS tumor survivors, seizures were associated with poorer (based on expected age-adjusted standard z-scores) executive function and processing speed. Seizure resolution was associated with improved attention and memory.
    • Among non-CNS tumor survivors, seizures were associated with worse function in all cognitive domains compared with survivors without seizures. Seizure severity was associated with worse processing speed, and resolution of seizures was associated with better executive function and attention.
    • Non-CNS survivors with seizures had poorer HRQOL outcomes (physical functioning, physical role limitations, and general health). Seizures in both non-CNS and CNS tumor survivors increased the risk of unemployment and part-time employment.

Peripheral neuropathy

Vinca alkaloid agents (vincristine and vinblastine) and heavy metals (cisplatin and carboplatin) may cause peripheral neuropathy.[91,92,93]

  • Peripheral neuropathy presents during treatment and appears to improve or clinically resolve after completion of therapy.[91] However, recent studies of long-term survivors suggest that chemotherapy-induced peripheral neuropathy is likely under-ascertained.[94]
  • Higher cumulative doses of vincristine and/or intrathecal methotrexate have been linked to neuromuscular impairments in long-term survivors of childhood ALL, which suggests that persistent effects of these agents may affect functional status in aging survivors.[91]
  • SJLIFE study investigators observed associations between peripheral neuropathy and impairment in performance measures of movement (mobility and walking endurance) and quality of life (physical functioning, role physical, and general health) among survivors of childhood ALL.[95]
  • Static-standing balance impairment (a predictor of falling within the next 90 days) was more common in survivors compared with controls but was not associated with peripheral neuropathy.[95]
  • Among adult survivors of extracranial solid tumors of childhood (median time from diagnosis, 25 years), standardized assessment of neuromuscular function disclosed motor impairment in association with vincristine exposure and sensory impairment in association with cisplatin exposure.[92]
    • Survivors with sensory impairment demonstrated a higher prevalence of functional performance limitations related to poor endurance and mobility restrictions.

Stroke or other cerebrovascular effects

  • Childhood CNS tumor survivors have a 43-fold elevated risk of stroke compared with siblings.[42,96]
    • Cranial radiation therapy (dose dependent), baseline atherosclerosis, hypertension, and African American ethnicity are identified risk factors.[97,98,99] For information about stroke, see the Cerebrovascular disease section.
  • A British CCSS (n = 13,457 survivors) that included 2,885 childhood CNS tumor survivors reported the following:[100]
    • CNS tumor survivors who were treated with cranial irradiation had an increased risk of developing cerebrovascular disease between the ages of 50 years and 65 years.
    • Compared with an expected incidence of 4.2%, the cumulative incidence of cerebrovascular disease in survivors was 11.6% by age 40 years, 16% by age 50 years, and 26% by age 65 years.
  • Among 271 CCSS participants with a history of stroke at a median age of 19 years, 70 reported a second stroke at a median age of 32 years.[101]
    • The 10-year cumulative incidence of late recurrent stroke was 21% overall, and 33% for those treated with 50 Gy or higher cranial radiation therapy.
    • Risk factors for recurrent stroke included the following:
      • Cranial radiation therapy 50 Gy or higher (HR, 4.4; 95% CI, 1.4–13.7).
      • Hypertension (HR, 1.9; 95% CI, 1.0–3.5).
      • Older age at first stroke (HR, 6.4; 95% CI, 1.8–23).
  • A PENTEC review identified 101 of 3,989 pediatric patients who experienced at least one cerebrovascular toxicity (transient ischemic attack, stroke, moyamoya, or arteriopathy).[102]
    • Predicted incidences were based on the radiation dose to the Circle of Willis: 0.2% at 30 Gy, 1.3% at 45 Gy, and 4.4% at 54 Gy.
    • At an attained age of 35 years, the predicted stroke incidence was 0.9% to 1.3% for 30 Gy, 1.8% to 2.7% for 45 Gy, and 2.8% to 4.1% for 54 Gy (compared with a baseline risk of 0.2%–1.0%).
    • At an attained age of 45 years, the predicted stroke incidence was 1.2% to 4.2% for 30 Gy, 4.5% to 8.6% for 45 Gy, and 6.7% to 13% for 54 Gy (compared with a baseline risk of 0.5%–1.0%).

Hypersomnia (daytime sleepiness) or narcolepsy

  • In a retrospective review of brain tumor patients treated at SJCRH, investigators identified 39 of 2,336 patients who were diagnosed with hypersomnia/narcolepsy, for a prevalence rate of 1,670 cases per 100,000, which is much higher than a prevalence rate of 20 to 50 cases per 100,000 reported in the general population.[103]
    • This may be an underestimate in childhood brain tumor survivors because many patients with mild-to-moderate symptoms, such as fatigue and sleep disturbances, may not be recognized or referred to a sleep specialist.
    • Hypersomnia/narcolepsy was diagnosed at a median of 6 years (range, 0.4–13.2 years) from tumor diagnosis and 4.7 years (range, 1.5–10.4 years) from cranial radiation.
    • Midline tumor location and antiepilepsy drug use correlated with hypersomnia/narcolepsy, while radiation dose higher than 30 Gy trended toward significance.
    • Posterior fossa tumor location was associated with a reduced risk of hypersomnia.
    • Treatment of hypersomnia/narcolepsy should be individualized and pharmacologic intervention with stimulants may be beneficial.
  • In a baseline evaluation of 82 childhood CNS tumor survivors (median age, 13.8 years) participating in a randomized controlled trial of neurofeedback, 48% of survivors endorsed sleep problems and scored significantly worse than the norm on the Sleep Disturbance Scale for Children in the subscales for initiating and maintaining sleep, excessive somnolence, and total scale.[104]
    • Emotional problems and/or hyperactivity/inattention were independent potential risk factors for sleep problems. Sleep problems were also associated with worse parent-reported executive functioning.

Other neurological sequelae

  • In a report from the CCSS that compared self-reported neurological late effects among 4,151 adult survivors of childhood ALL with siblings, survivors were at elevated risk for late-onset coordination problems, motor problems, seizures, and headaches.[89]
    • The overall cumulative incidence was 44% at 20 years. Serious headaches were most common, with a cumulative incidence of 25.8% at 20 years, followed by focal neurological dysfunction (21.2%) and seizures (7%).
    • Children who were treated with regimens that included cranial irradiation for ALL and those who suffered relapse were at increased risk for late-onset neurological sequelae.
  • A cross-sectional study evaluated neurological morbidity and quality of life in 162 survivors of childhood ALL (median age at evaluation, 15.7 years; median time from completion of therapy, 7.4 years) in concert with a clinical neurological examination.[105]
    • Neurological symptoms were present in 83% of survivors, but symptom-related morbidity was low and quality of life was high in most survivors.
    • The most commonly reported symptoms included neuropathy (63%), headache (46.9%), dizziness (33.3%), and back pain (22.8%).
    • Female sex, ten doses or more of intrathecal chemotherapy, cranial irradiation, CNS leukemia at diagnosis, and history of ALL relapse were associated with neurological morbidity.
  • Neuroimaging studies of irradiated and nonirradiated ALL survivors demonstrate a variety of CNS abnormalities, including leukoencephalopathy, cerebral lacunes, cerebral atrophy, and dystrophic calcifications (mineralizing microangiopathy).[52,58,106,107]
    • Among these, abnormalities of cerebral white matter integrity and volume have been correlated with neurocognitive outcomes.
  • Cavernomas have also been observed in ALL survivors treated with cranial irradiation. They have been speculated to result from angiogenic processes as opposed to tumorigenesis.[108]
  • In a retrospective cross-sectional study, 101 survivors of childhood ALL (mean time since diagnosis, 27.6 years) who were treated with cranial irradiation (63.4% received ≤18 Gy) underwent neurocognitive testing and 3T brain MRI.[109]
    • Small focal intracerebral hemorrhages that are only visible on exquisitely sensitive MRI sequences were identified and localized using susceptibility weighted imaging.
    • At least one microbleed was present in 85% of survivors, and they occurred more frequently in frontal lobes.
    • A radiation dose of 24 Gy conveyed a fivefold greater risk of having multiple microbleeds when compared with a dose of 18 Gy.
    • No significant difference was found in neurocognitive scores with either the absence or presence of microbleeds or their location.
  • CCSS investigators evaluated treatment-related neurological sequelae in survivors of childhood CNS tumors.[88]
    • In 1,876 5-year survivors of CNS tumors from the CCSS, the cumulative incidence of headaches increased from 38% at 5 years to 53% at 30 years since diagnosis.
    • Coordination problems increased from 21% at 5 years to 53% at 30 years since diagnosis, and motor impairment increased from 21% to 35% during this same time period.
    • Increased risk of motor impairment was associated with tumor recurrence (HR, 2.6), development of a meningioma (HR, 2.3), and stroke (HR, 14.9).
    • The cumulative incidence of hearing loss increased from 9% at 5 years to 23% at 30 years, cumulative incidence of tinnitus increased from 8% at 5 years to 21% at 30 years, and cumulative incidence of vertigo increased from 9% at 5 years to 17% at 30 years.
    • Risks of motor impairment (HR, 7.6) and hearing loss (HR, 18.4) were elevated compared with siblings.
  • CCSS investigators estimated the prevalence and cumulative incidence of neuromuscular dysfunction (motor or sensory dysfunction) among 25,583 childhood cancer survivors and 5,044 siblings.[110]
    • Neuromuscular dysfunction was prevalent in 14.7% of survivors 5 years after diagnosis, compared with 1.5% in siblings (prevalence ratio [PR], 9.9%; 95% CI, 7.9–12.4).
    • The prevalence of neuromuscular dysfunction was highest in survivors of CNS tumors (PR, 27.6; 95% CI, 22.1–34.6) and sarcomas (PR, 11.5; 95% CI, 9.1–14.5).
    • The 20-year cumulative incidence increased to 24.3% in survivors 20 years after diagnosis.
    • Cancer treatments associated with increased prevalence of neuromuscular dysfunction included spinal radiation therapy, increasing doses of cranial radiation therapy, and platinum agents.
    • Neuromuscular dysfunction was associated with downstream adverse outcomes, including concurrent or later obesity (PR, 1.1; 95% CI, 1.1–1.2), anxiety (PR, 2.5; 95% CI, 2.2–2.9), depression (PR, 2.1; 95% CI, 1.9–2.3), and lower likelihood of graduating college (PR, 0.92; 95% CI, 0.90–0.94) and finding employment (PR, 0.8; 95% CI, 0.8–0.9).

Table 4 summarizes CNS late effects and the related health screenings.

Table 4. Central Nervous System Late Effectsa
Predisposing Therapy Neurological Effects Health Screening
IQ = intelligence quotient; IT = intrathecal; IV = intravenous.
a Adapted from theChildren's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers.
Heavy metals (carboplatin, cisplatin) Peripheral sensory neuropathy Neurological examination
Vinca alkaloid agents (vinblastine, vincristine) Peripheral sensory or motor neuropathy (areflexia, weakness, foot drop, paresthesias) Neurological examination
Methotrexate (high dose IV or IT); cytarabine (high dose IV or IT); radiation exposing the brain Clinical leukoencephalopathy (spasticity, ataxia, dysarthria, dysphagia, hemiparesis, seizures); headaches; seizures; sensory deficits History: cognitive, motor, and/or sensory deficits, seizures
Neurological examination
Radiation exposing cerebrovascular structures Cerebrovascular complications (stroke, Moyamoya disease, occlusive cerebral vasculopathy) History: transient/permanent neurological events
Blood pressure test
Neurological examination
Neurosurgery–brain Motor and/or sensory deficits (paralysis, movement disorders, ataxia, eye problems [ocular nerve palsy, gaze paresis, nystagmus, papilledema, optic atrophy]); seizures Neurological examination
Neurology evaluation
Neurosurgery–brain Hydrocephalus; shunt malfunction Abdominal x-ray
Neurosurgery evaluation
Neurosurgery–spine Neurogenic bladder; urinary incontinence History: hematuria, urinary urgency/frequency, urinary incontinence/retention, dysuria, nocturia, abnormal urinary stream
Neurosurgery–spine Neurogenic bowel; fecal incontinence History: chronic constipation, fecal soiling
Rectal examination
Predisposing Therapy Neurocognitive Effects Health Screening
Methotrexate (high-dose IV or IT); cytarabine (high-dose IV or IT); radiation exposing the brain; neurosurgery–brain Neurocognitive deficits (executive function, memory, attention, processing speed, etc.); learning deficits; diminished IQ; behavioral change Assessment of educational and vocational progress
Formal neuropsychological evaluation

Psychosocial

Many childhood cancer survivors report reduced quality of life, impaired health status, or other adverse psychosocial outcomes, compared with siblings or noncancer population groups.[111,112] Vulnerable groups have been identified related to sociodemographic factors (e.g., female sex), specific cancer diagnoses (e.g., CNS tumor), cancer treatments (e.g., cranial radiation therapy), health behaviors (e.g., smoking), and type/cumulative burden of chronic health conditions. The diagnosis of childhood cancer may also affect psychosocial outcomes and the expected attainment of functional and social independence in adulthood. Several investigations have demonstrated that survivors of pediatric CNS tumors are particularly vulnerable.[48,113]

Evidence for adverse psychosocial adjustment after childhood cancer has been derived from sources, ranging from patient-reported or proxy-reported outcomes to data from population-based registries. The former may be limited by small sample size, cohort selection and participation bias, and variable methods and venues (clinical vs. distance-based survey) of assessments. The latter is often not well correlated with clinical and treatment characteristics that permit the identification of survivors at high risk of psychosocial deficits.

Achievement of social milestones

Survivors with neurocognitive deficits are particularly vulnerable to deficits in achievement of expected social outcomes during adulthood.

  • In a population-based study of adult survivors of CNS tumors diagnosed in childhood or adolescence, survivors had significantly poorer self-perception and self-esteem than did individuals in the general population. Female sex, persistent visible physical sequelae, specific tumor type, and treatment with cranial radiation therapy predicted poor self-perception outcomes.[114]
  • In a series of CNS malignancy survivors (n = 802) reported from the CCSS, adverse outcome on multiple indicators of successful adult adjustment (educational achievement, income, employment, and marital status) were most prevalent among survivors who reported neurocognitive dysfunction.[41]
  • Collectively, studies evaluating psychosocial outcomes among CNS tumor survivors indicate deficits in social competence that worsen over time.[115] This includes problems with peer rejection and isolation in childhood/adolescence, and the inability to develop friendships and romantic relationships as adults.
  • In a CCSS study that evaluated predictors of independent living status across diagnostic groups, adult survivors of childhood cancer with neurocognitive, psychological, or physical late effects were less likely to live independently as adults than were siblings in the comparison group.[116]
  • In an SJLIFE study of 224 survivors of CNS tumors (median current age, 26 years; median time from diagnosis, 18 years), neurocognitive impairment was significantly associated with lower educational attainment, unemployment, and dependent living.[3]
    • Among one subgroup, significant impairments in social perceptions skills, including affect recognition, contributed to limited achievement of functional outcomes. Self-reports of social adjustment were generally within normal limits, suggesting limited self-insight into social deficits.[117]
  • In a series of 1,560 adolescent survivors of childhood ALL treated with chemotherapy alone, the CCSS identified a significant proportion of survivors who still experienced problems with headstrong behavior, inattention-hyperactivity, and social withdrawal, which were associated with an increased risk of special education placement and predicted reduced adult educational attainment.[69]
  • In a cross-sectional study of 855 childhood leukemia survivors (mean, 10.2 years from diagnosis) in the Leucémie de l'Enfant et de l'Adolescent (LEA) cohort, investigators identified independent factors associated with repeating a grade in school, including low parental education and household financial difficulties, emphasizing the importance of considering socioeconomic factors that may affect access to educational support. Survivors who were adolescents (aged 11–17 years) at diagnosis were also at greater risk than were survivors who were children (aged <11 years) at diagnosis.[118]
  • In a population-based, cross-sectional, survivorship study, 28% of adolescent and young adult (AYA) survivors of sarcoma (aged 18–39 years at diagnosis; median time from diagnosis, 6.2 years) experienced impaired social functioning.[119] Multivariable analysis identified independent associations with impaired social functioning and unemployment (OR, 3.72; 95% CI, 1.26–10.97) and having to make lifestyle changes because of financial problems caused by an individual's physical condition or medical treatment (OR, 3.39; 95% CI, 1.12–10.30). In contrast, better social support reduced the risk of impaired social functioning (OR, 0.74; 95% CI, 0.57–0.96).

Psychological distress and suicidality

Childhood cancer survivors are also at risk of developing symptoms of psychological distress and suicidality.[120]

  • The SJLIFE study was used to compare the risks of suicidal ideation, suicidal behaviors, and mortality in adult survivors of childhood cancer with those of the general population.[121]
    • Survivors (n = 3,096) reported a similar 12-month prevalence of suicidal ideation compared with the general population (standardized incidence ratio [SIR], 0.68) and a lower prevalence of suicidal behaviors (planning: SIR, 0.17; attempts: SIR, 0.07) and mortality (standardized mortality ratio, 0.60).
    • Among survivors, depression (RR, 12.30), anxiety (RR, 2.19), and financial stress (RR, 1.47) were found to be risk factors associated with suicidal ideation.
    • Survivors who were currently single, widowed, or divorced; who were not working full time; who reported financial stress during the previous year; and who reported sleep disturbances had an approximately 30% to 50% higher prevalence of suicidal ideation.
  • A CCSS study evaluated the prevalence of recurrent suicidal ideation among 9,128 adult long-term survivors of childhood cancer.[122]
    • Survivors were more likely to report late suicidal ideation (OR, 1.9; 95% CI, 1.5–2.5) and recurrent suicidal ideation (OR, 2.6; 95% CI, 1.8–3.8) compared with siblings.
    • History of seizure was associated with a twofold increased likelihood of suicide ideation in survivors.
  • A population-based study evaluated suicide among adults treated for cancer before age 25 years.[123]
    • The absolute risk of suicide was low (24 cases among 3,375 deaths).
    • The HR of suicide was increased among individuals treated for cancer in childhood (0–14 years; HR, 2.5; 95% CI, 1.7–3.8) and in adolescence and young adulthood (15–24 years; HR, 2.3; 95% CI, 1.2–4.6).

The presence of chronic health conditions can also impact aspects of psychological health.

  • In a study that evaluated psychological outcomes among long-term survivors treated with HSCT, 22% of survivors and 8% of sibling controls reported adverse outcomes. Somatic distress was the most prevalent condition and affected 15% of HSCT survivors, representing a threefold higher risk compared with siblings. HSCT survivors with severe or life-threatening health conditions and active chronic GVHD had a twofold increased risk of somatic distress.[124]
  • A report from the CCSS revealed that the presence of chronic pulmonary, endocrine, and cardiac conditions was associated with increased risk of psychological distress symptoms in a sample of 5,021 adult survivors of childhood cancer.[125]
  • In a CCSS investigation that evaluated long-term psychological and educational outcomes among survivors of neuroblastoma, survivors demonstrated elevated risks of psychological impairment, which was associated with the use of special education services and lower educational attainment. The presence of two or more chronic health conditions, but not common treatment exposures, predicted psychological impairment. Specifically, pulmonary disease predicted impairment in all five psychological domains, whereas endocrine disease and peripheral neuropathy each predicted impairment in three domains.[126]

Incorporation of psychological screening into clinical visits for childhood cancer survivors may be valuable. However, limiting such evaluations to those returning to long-term follow-up clinics may result in a biased subsample of survivors with more difficulties, and precise prevalence rates may be difficult to establish.

  • In a study of 101 adult survivors of childhood cancer, psychological screening was performed during a routine annual evaluation at the survivorship clinic at the Dana Farber Cancer Institute.[127]
    • On the Symptom Checklist 90 Revised, 32 survivors had a positive screen (indicating psychological distress), and 14 survivors reported at least one suicidal symptom.
    • Risk factors for psychological distress included survivors' dissatisfaction with physical appearance, poor physical health, and treatment with cranial irradiation.
    • This instrument was shown to be feasible for use in the clinic-visit setting because the psychological screening was completed in less than 30 minutes and did not appear to cause distress in the survivors in 80% of cases.

For more information about psychological distress, depression, and cancer patients, see Adjustment to Cancer: Anxiety and Distress and Depression.

Serious mental illnesses

A population-based study from Taiwan compared the prevalence of serious mental illnesses in 5,121 childhood and adolescent cancer survivors with that of population controls.[128]

  • Survivors (mean age, 9 years; 60% were 5 or more years from diagnosis) showed increased risks of six serious mental illnesses compared with controls. These disorders included the following:
    • Autism spectrum disorder (HR, 10.42; 95% CI, 4.58–23.69).
    • ADHD (HR, 6.59; 95% CI, 4.91–8.86).
    • Bipolar disorder (HR, 2.93; 95% CI, 1.26–6.80).
    • Major depressive disorder (HR, 1.88; 95% CI, 1.26–2.79).
    • Obsessive-compulsive disorder (OCD) (HR, 3.37; 95% CI, 1.33–8.52).
    • Post-traumatic stress disorder (PTSD) (HR, 6.10; 95% CI, 1.46–25.54).
  • Survivors were younger than controls at the time of diagnosis of ADHD, schizophrenia, major depressive disorder, and OCD.
  • Risks of serious mental illnesses varied according to specific cancer types. The greatest number of major psychiatric disorders was observed among survivors of brain cancer and lymphatic/hematopoietic tissue cancer.

A population-based study linked individuals with a history of six common cancers diagnosed at age 15 to 21 years to provincial health care data to compare rates of outpatient (family physician and psychiatrist) visits for psychiatric indications and time to severe psychiatric events (emergency room visit, hospitalization, and suicide). The study included 2,208 AYA cancer patients and 10,457 matched controls.[129]

  • Five-year AYA survivors experienced higher rates of outpatient mental health visits than did controls (671 vs. 506 visits per 1,000 person-years; RR, 1.3), higher risk of a severe psychiatric episode (HR, 1.2), and higher risk of a psychotic disorder–associated severe event (HR, 2.0).
  • Treatment in an adult center was associated with substantially higher outpatient visit rates compared with treatment in pediatric settings (RR, 1.8).

PTSD after childhood cancer

Despite the many stresses associated with the diagnosis of cancer and its treatment, studies have generally shown low levels of post-traumatic stress symptoms and PTSD in children with cancer, typically no higher than those in healthy comparison children.[130]

  • The prevalence of PTSD and post-traumatic stress symptoms has been reported in 15% to 20% of young adult survivors of childhood cancer, with estimates varying based on criteria used to define these conditions.[131]
  • In a cohort of 5,121 childhood and adolescent cancer survivors (mean age, 9 years), the incidence of PTSD was 0.59%. Compared with controls, survivors showed a 6.10-fold elevated risk of being diagnosed with PTSD. Brain cancer survivors had the highest risk of all cancer diagnoses for PTSD (HR, 18.50; 95% CI, 2.11–162.64).[128]
  • Patient and parent adaptive style appear to be significant determinants of PTSD in the pediatric oncology setting.[132,133]
  • Survivors with PTSD reported more psychological problems and negative beliefs about their illness and health status than did those without PTSD.[134,135]
  • A subset of adult survivors (9%) from the CCSS reported functional impairment and/or clinical distress in addition to the set of symptoms consistent with a full diagnosis of PTSD.[136]
    • PTSD was significantly more prevalent in survivors than in sibling comparisons.
    • PTSD was significantly associated with being unmarried, having an annual income of less than $20,000, being unemployed, having a high school education or less, and being older than 30 years.
    • Survivors who were treated with cranial irradiation before age 4 years were at particularly higher risk of developing PTSD.
    • Intensive cancer-directed therapy was also associated with increased risk of full PTSD.
  • Because avoidance of places and persons associated with the cancer is part of PTSD, the syndrome may interfere with obtaining appropriate health care.[137]
    • Those with PTSD perceive greater current threats to their lives or the lives of their children.
    • Other risk factors for PTSD include poor family functioning, decreased social support, and noncancer stressors.

Psychosocial outcomes among childhood, adolescent, and young adult cancer survivors

Most research on late effects after cancer has focused on individuals with a cancer diagnosis during childhood. Little is known about the specific impact of a cancer diagnosis with an onset in adolescence or the impact of childhood cancer on AYA psychosocial outcomes.

Evidence (psychosocial outcomes in AYA cancer survivors):

  1. Adult survivors of cancer diagnosed during adolescence (aged 15–18 years) (N = 825) were compared with an age-matched sample from the general population and a comparison group of adults without cancer.[138]
    • Female survivors of adolescent cancers achieved fewer developmental milestones related to their psychosexual development, such as having their first boyfriend, or they reached these milestones later.
    • Male survivors were more likely to live with their parents than were same-sex controls.
    • Adolescent cancer survivors were less likely to have ever married or have had children. Survivors were significantly older at their first marriage and at the birth of their first child than were their age-matched samples.
    • Survivors in this cohort were also significantly less satisfied with their general and health-related life than were people in a community-based control group. Impaired general and health-related life satisfaction were associated with somatic late effects, symptoms of depression and anxiety, and lower rates of posttraumatic growth.[139]
  2. A survey of 4,054 AYA cancer survivors and 345,592 respondents who had no history of cancer reported the following:[140]
    • AYA cancer survivors were more likely to smoke (26% vs. 18%), be affected by obesity (31% vs. 27%), and have chronic conditions such as cardiovascular disease (14% vs. 7%), hypertension (35% vs. 9%), asthma (15% vs. 8%), disability (36% vs. 18%), and poor mental health (20% vs. 10%).
    • They were also less likely to receive medical care because of cost (24% vs. 15%).
  3. The CCSS evaluated outcomes of 2,979 adolescent survivors and 649 siblings of childhood cancer survivors to determine the incidence of difficulty in six behavioral and social domains (depression/anxiety, being headstrong, attention deficit, peer conflict/social withdrawal, antisocial behaviors, and social competence).[141]
    • Survivors were 1.5 times (95% CI, 1.1–2.1) more likely than siblings to have symptoms of depression/anxiety and 1.7 times (95% CI, 1.3–2.2) more likely than siblings to have antisocial behaviors.
    • Scores in the depression/anxiety, attention deficit, and antisocial domains were significantly elevated in adolescents treated for leukemia or CNS tumors, compared with the scores in siblings.
    • In addition, survivors of neuroblastoma had difficulty in the depression/anxiety and antisocial domains.
    • CNS-directed treatments (cranial radiation therapy and/or intrathecal methotrexate) were specific risk factors for adverse behavioral outcomes.
  4. Another CCSS study evaluated psychological and neurocognitive function in 2,589 long-term cancer survivors who were diagnosed during adolescence and young adulthood.[142]
    • Compared with a sibling cohort, survivors diagnosed during adolescence and young adulthood reported higher rates of depression (OR, 1.55; 95% CI, 1.04–2.30) and anxiety (OR, 2.00; 95% CI, 1.17–3.43) and reported more cognitive problems affecting task efficiency (OR, 1.72; 95% CI, 1.21–2.43), emotional regulation (OR, 1.74; 95% CI, 1.26–2.40), and memory (OR, 1.44; 95% CI, 1.09–1.89).
    • Survivors of lymphoma and sarcoma diagnosed during later adolescence were at reduced risk of psychosocial and neurocognitive problems than were those diagnosed before age 11 years. These outcomes did not differ by age at diagnosis among CNS tumor and leukemia survivors.
    • Survivors diagnosed during adolescence and young adulthood were also significantly less likely than sibling controls to have attained a post–high school education, be working full time, be married, or be living independently; inferior social outcomes were related to neurocognitive symptoms.
  5. A follow-up CCSS study evaluated profiles of symptom comorbidities in 3,993 adolescents (aged 13–17 years) treated for cancer.[143] Latent profile analysis identified four symptom profiles:
    • No significant symptoms.
    • Elevated internalizing symptoms (anxiety and/or depression, social withdrawal, and attention problems).
    • Elevated externalizing symptoms (headstrong behavior and attention problems).
    • Elevated internalizing and externalizing symptoms.

    Overall results support that behavioral, emotional, and social symptoms frequently co-occur and are associated with treatment exposures (cranial radiation, corticosteroids, and methotrexate) and late effects (obesity, cancer-related pain, and sensory impairments) in adolescent survivors diagnosed between 1970 and 1986.

  6. Another CCSS study characterized the prevalence and risk of pain, clinically significant interference in daily activities because of pain, and recurrent pain in 10,012 adult survivors of childhood cancer (median time since diagnosis, 23 years).[144]
    • A significant minority of survivors endorsed moderate to severe pain (29%), moderate to extreme pain interference (20%), and moderate to severe recurrent pain (9%).
    • Older age at diagnosis and follow-up, female sex, and presence of grades 3 to 4 chronic medical conditions were consistently associated with an increased risk of worse pain outcomes.
    • Minority racial and ethnic groups, diagnosis of CNS tumor, and treatment with platinum-based chemotherapy and cranial radiation were associated with an increased risk of late-occurrence pain and pain interference.
    • Depression and anxiety were associated with increased risk of all pain outcomes, and poor vitality mediated the effects of anxiety on high pain and pain interference.
  7. An SJLIFE study evaluated the associations between comprehensive medical, neurocognitive, and physical performance assessments and self-reported pain, quality of life, and social functioning in 2,836 survivors (mean age, 32.2 years; mean time since diagnosis, 23.7 years) and 343 noncancer community controls.[145]
    • Moderate-to-very-severe pain with moderate-to-extreme daily interference was endorsed by 18% of survivors, compared with 8% of controls (P < .001).
    • Survivors of soft tissue sarcoma (OR, 9.25), non-Hodgkin lymphoma (OR, 4.13), and Ewing sarcoma and/or osteosarcoma (OR, 3.93) had the highest odds of pain with daily interference, compared with controls.
    • In multivariable models that included treatment exposures, histories of amputation (OR, 1.89) and/or limb-sparing surgery (OR, 2.30) were associated with increased odds of pain with daily interference.
    • Pain with daily interference was associated with an increased risk of impaired neurocognition (attention: RR, 1.88; memory: RR, 1.65) and physical functioning (aerobic capacity: RR, 2.29; mobility: RR, 1.71).
    • Pain with daily interference was also associated with an increased risk of impaired social functioning (inability to hold a job and/or attend school: RR, 4.46; assistance with routine and/or personal care needs: RR, 5.64), and health-related quality of life (physical: RR, 6.34; emotional: RR, 2.83).
  8. A Nordic, register-based cohort study evaluated whether childhood cancer survivors (n = 18,621) were at a higher risk of developing psychiatric disorders later in life than their siblings (n = 24,775) and the general population (n = 88,630).[146]
    • The cumulative incidence of contact with a psychiatric hospital by age 30 years was 15.9% for childhood cancer survivors, 14.0% for siblings, and 12.7% for matched (by birth year, sex, and country/municipality) population controls.
    • The absolute difference was small, but survivors were still at a higher RR for any psychiatric hospital contact than their siblings (1.39) and matched controls (HR, 1.34).

Evidence (functional and social independence):

  1. In a study of 665 survivors of CNS tumors (54% male; 52% treated with cranial radiation therapy; median age, 15 years; and 12 years from diagnosis), CCSS investigators observed the following:[113]
    • Almost 50% of survivors experienced social difficulties related to peer relationships that exceeded those of survivors of solid tumors and sibling controls.
    • Cranial radiation exposure predicted impaired social and peer relationships, and cognitive impairment mediated these associations.
  2. An SJLIFE study investigated functional and social independence in 306 CNS tumor survivors (astrocytoma [n = 130], medulloblastoma [n = 77], ependymoma [n = 36], and other [n = 63]; median age, 25 years; and time since diagnosis, 16.8 years).[48]
    • Only 40% of long-term survivors in the study cohort achieved complete independence as adults.
    • Predictors of nonindependence included treatment with craniospinal irradiation, history of hydrocephalus with shunting, and younger age at diagnosis.
    • Beyond impaired IQ scores, functional limitations in aerobic capacity, flexibility, and adaptive physical function were significantly associated with nonindependence.

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Late Effects of the Digestive System

Dental

Overview

Chemotherapy, radiation therapy, and surgery can result in cosmetic and functional abnormalities of the oral cavity and dentition. The quality of current evidence regarding this outcome is limited by retrospective data collection, small sample size, cohort selection and participation bias, and heterogeneity in treatment approach, time since treatment, and method of ascertainment.

Oral and dental complications reported in childhood cancer survivors include the following:

  • Abnormalities of tooth development.
  • Salivary gland dysfunction.
  • Abnormalities of craniofacial development.
  • Osteoradionecrosis.
  • Second cancers in the oral cavity.

Abnormalities of tooth development

Abnormalities of dental development reported in childhood cancer survivors include the following:[1,2,3,4,5,6,7,8,9,10,11,12]

  • Absence of tooth development.
  • Microdontia.
  • Enamel hypoplasia.
  • Root malformation.
  • Hypodontia.

The prevalence of hypodontia has varied widely in series depending on age at diagnosis, treatment modality, and method of ascertainment.

Cancer treatments that have been associated with dental maldevelopment include the following:[3,10]

  • Head and neck radiation therapy.
  • Any chemotherapy.
  • Hematopoietic stem cell transplant (HSCT).

Children younger than 5 years are at greatest risk of dental anomalies, including root agenesis, delayed eruption, enamel defects, and/or excessive caries related to disruption of ameloblast (enamel producing) and odontoblast (dentin producing) activity early in life.[3]

Key findings related to cancer treatment effect on tooth development include the following:

Radiation therapy

  • Radiation directed at the oral cavity or surrounding structures increases the risk of dental anomalies because ameloblasts can be permanently damaged by doses as low as 10 Gy. In addition, salivary function is impacted by exposure to major and minor glands.[3,4,5]
  • The most significant degree of tooth aplasia or delayed eruption occurs in younger children (aged <4 years) who are exposed to radiation doses of 20 Gy or higher.[13]
  • Developing teeth may be irradiated when treating head and neck sarcomas, Hodgkin lymphoma, neuroblastoma, central nervous system leukemia, nasopharyngeal cancer, and brain tumors, or during total-body irradiation (TBI) for HSCT.
  • Doses of 10 Gy to 40 Gy can cause root shortening or abnormal curvature, dwarfism, and hypocalcification.[14]
  • Significant dental abnormalities, including mandibular or maxillary hypoplasia, increased caries, hypodontia, microdontia, root stunting, and xerostomia have been reported in more than 85% of survivors of head and neck rhabdomyosarcoma treated with radiation doses higher than 40 Gy.[4,15]
  • In the St. Jude Life (SJLIFE) cohort, survivors who received radiation therapy that potentially exposed the oral cavity were more likely to report at least one dental health problem (odds ratio [OR], 1.48; 95% confidence interval [CI], 1.26–1.72) and at least one soft tissue abnormality (OR, 1.52; 95% CI, 1.25–1.84) after controlling for socioeconomic factors, age at last follow-up and diagnosis, other treatment exposures, and access to dental services.[12]

Chemotherapy

  • Chemotherapy, especially exposure to alkylating agents, can affect tooth development.[3,5,6]
  • Chemotherapy for the treatment of leukemia or neuroblastoma is associated with shortening and thinning of the premolar roots and enamel abnormalities.[8,16,17]
  • Childhood Cancer Survivor Study (CCSS) investigators identified age younger than 5 years and increased exposure to cyclophosphamide as significant risk factors for developmental dental abnormalities in long-term survivors of childhood cancer.[3]
  • In the SJLIFE study, survivors who received classic alkylating agents (OR, 1.6; 95% CI, 1.36–1.88) or anthracycline antibiotics (OR, 1.22; 95% CI, 1.04–1.42) were more likely to report at least one dental health problem after controlling for socioeconomic factors, age at last follow-up and diagnosis, other treatment exposures, and access to dental services.[12]

HSCT

  • HSCT conditioning, especially regimens containing TBI, may result in tooth agenesis and root malformation.[1,2]
  • Younger children who have not developed secondary teeth are most vulnerable.[1,2,5]
  • Children who undergo HSCT with TBI may develop short V-shaped roots, microdontia, enamel hypoplasia, and/or premature apical closure.[1,2,7]
  • Younger age at HSCT is associated with greater severity in dental maldevelopment and deficit in vertical growth of the lower face.[8]
  • Dental abnormalities have been reported in patients who underwent HSCT without TBI, particularly in patients younger than 2 years at the time of the transplant.[17]

Salivary gland dysfunction

Xerostomia, the sensation of dry mouth, is a potential side effect after head and neck irradiation or HSCT that can severely impact quality of life.[18]

  • Complications of reduced salivary secretion include the following:[18,19]
    • Increased caries.
    • Susceptibility to oral infections.
    • Sleep disturbances.
    • Difficulties with chewing, swallowing, and speaking.
  • The prevalence of salivary gland dysfunction after cancer treatment varies based on measurement techniques (patient report vs. stimulated or unstimulated salivary secretion rates).[20]
  • In general, the prevalence of self-reported persistent posttherapy xerostomia is low among childhood cancer survivors.
  • In the CCSS, the prevalence of self-reported xerostomia in survivors was 2.8% compared with 0.3% in siblings, with an increased risk in survivors older than 30 years.[3]

Key findings related to cancer treatment effect on salivary gland function include the following:

Radiation therapy

  • Salivary gland irradiation incidental to treatment of head and neck malignancies or Hodgkin lymphoma causes a qualitative and quantitative change in salivary flow, which can be reversible after doses of lower than 40 Gy but may be irreversible after higher doses, depending on whether sensitizing chemotherapy is also administered.[18]
  • In a German study of 114 pediatric patients, the risk of acute and late xerostomia increased with parotid and submandibular gland dose. In general, grade 1 or higher xerostomia was seen in patients who received a maximum dose of higher than 20 Gy to the salivary glands. The odds of both acute and late xerostomia were higher in patients who received concurrent chemotherapy compared with those who received radiation therapy alone, with an OR for acute xerostomia of 3.64 (95% CI, 1.49–8.89) and for late xerostomia of 5.15 (95% CI, 1.20–22.15).[21]
  • The Pediatric Normal Tissue Effects in the Clinic (PENTEC) initiative reported on late effects for childhood cancer survivors who were treated with radiation therapy for head and neck cancers.[22] Grades 1 or higher xerostomia were seen in patients who received a maximum dose of more than 20 Gy to the salivary glands. The odds of both acute and chronic xerostomia were greater in patients who had received concurrent chemotherapy and radiation therapy (acute xerostomia OR, 3.64; 95% CI, 1.49–8.89 and late xerostomia OR, 5.15; 95% CI, 1.20–22.15), compared with patients who were treated with radiation therapy alone. A mean parotid dose of 35 to 40 Gy was associated with a 32% risk of higher than grade 2 acute xerostomia and a 13% to 32% risk of chronic xerostomia.

HSCT

  • HSCT recipients are at increased risk of salivary gland dysfunction related to transplant conditioning or graft-versus-host disease (GVHD).
  • GVHD can cause hyposalivation and xerostomia with resultant dental disease.
  • In a study of pediatric HSCT survivors, 60% of those exposed to a conditioning regimen with cyclophosphamide and 10 Gy single-dose TBI had decreased salivary secretion rates, compared with 26% of those who received cyclophosphamide and busulfan.[23]
  • In another study, the prevalence of reduced salivary secretion did not differ among long-term survivors on the basis of the conditioning regimen (single-dose TBI, 47%; fractionated TBI, 47%; busulfan, 42%).[24]

Chemotherapy

  • The association of chemotherapy alone with xerostomia remains controversial.[18]
  • Only one study of pediatric patients demonstrated an excess risk (OR, 12.32; 95% CI, 2.1–74.4) of decreased stimulated saliva flow rates among patients treated with cyclophosphamide. However, an increase in dental caries was not noted and patient-reported xerostomia was not evaluated.[6]

Abnormalities of craniofacial development

  • Craniofacial maldevelopment is a common adverse outcome among children treated with high-dose radiation therapy to the head and neck that frequently occurs in association with other oral cavity sequelae such as dental anomalies, xerostomia, and trismus.[4,25]
  • The extent and severity of musculoskeletal disfigurement is related to age at treatment and radiation therapy volume and dose, with higher risk observed among younger patients and those who received 30 Gy or higher of radiation therapy.[25]

Other oral health complications

  • Osteoradionecrosis of the jaw is a rare complication observed in childhood survivors treated with high-dose craniofacial radiation (>40 Gy), particularly after dental extractions in irradiated mandibles.[26,27]
  • Remediation of cosmetic and functional abnormalities often requires multiple surgical interventions.
  • The impact of infectious complications and alterations in the microflora during and after therapy is not known.[5]

Posttherapy management

  • Some studies suggest that fluoride products or chlorhexidine rinses may be beneficial in patients who have undergone radiation therapy.[28]
  • Dental caries are a problematic consequence of reduced salivary quality and flow. The use of topical fluoride can dramatically reduce the frequency of caries, and saliva substitutes and sialagogues can ameliorate sequelae such as xerostomia.[19]

For more information about oral complications in cancer patients, see Oral Complications of Cancer Therapies.

Table 5 summarizes oral and dental late effects and the related health screenings.

Table 5. Oral/Dental Late Effectsa
Predisposing Therapy Oral/Dental Effects Health Screening/Interventions
CT = computed tomography; GVHD = graft-versus-host disease; HSCT = hematopoietic stem cell transplant; MRI = magnetic resonance imaging.
a Adapted from theChildren's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers.
Any chemotherapy; radiation exposing oral cavity Dental developmental abnormalities; tooth/root agenesis; microdontia; root thinning/shortening; enamel dysplasia Dental evaluation and cleaning every 6 months
Regular dental care including fluoride applications
Consultation with orthodontist experienced in management of irradiated childhood cancer survivors
Baseline Panorex x-ray before dental procedures to evaluate root development
Radiation exposing oral cavity Malocclusion; temporomandibular joint dysfunction Dental evaluation and cleaning every 6 months
Regular dental care including fluoride applications
Consultation with orthodontist experienced in management of irradiated childhood cancer survivors
Baseline Panorex x-ray before dental procedures to evaluate root development
Referral to otolaryngologist for assistive devices for jaw opening
Radiation exposing oral cavity; HSCT with history of chronic GVHD Xerostomia/salivary gland dysfunction; periodontal disease; dental caries; oral cancer (squamous cell carcinoma) Dental evaluation and cleaning every 6 months
Supportive care with saliva substitutes, moistening agents, and sialogogues (pilocarpine)
Regular dental care including fluoride applications
Referral for biopsy of suspicious lesions
Radiation exposing oral cavity (≥40 Gy) Osteoradionecrosis History: impaired or delayed healing after dental work
Examination: persistent jaw pain, swelling or trismus
Imaging studies (x-ray, CT scan and/or MRI) may assist in making diagnosis
Surgical biopsy may be needed to confirm diagnosis
Consider hyperbaric oxygen treatments

Digestive Tract

Overview

The gastrointestinal (GI) tract is sensitive to the acute toxicities of chemotherapy, radiation therapy, and surgery. These important treatment modalities can also result in some long-term issues in a treatment- and dose-dependent manner.

Reports published about long-term GI tract outcomes are limited by retrospective data collection, small sample size, cohort selection and participation bias, heterogeneity in treatment approach, time since treatment, and method of ascertainment.

Treatment-related late effects include the following:

  • Upper and lower digestive tract late effects associated with dose intensity of chemotherapy and/or abdominal radiation.
  • Adhesions secondary to abdominal surgery predisposing to postoperative bowel obstruction.

Digestive tract–related late effects include the following:

  • Esophageal dysmotility.
  • Esophageal stricture.
  • Gastroesophageal reflux.
  • Gastritis, enteritis, or colitis.
  • GI motility dysfunction (diarrhea, constipation, encopresis, bowel obstruction).
  • Subsequent malignant neoplasms (SMNs).

Impact of cancer histology on GI outcomes

The abdomen is a relatively common location for several pediatric malignancies, including rhabdomyosarcoma, Wilms tumor, lymphoma, germ cell tumors, and neuroblastoma.

Intra-abdominal tumors often require multimodal therapy, occasionally necessitating resection of bowel, bowel-injuring chemotherapy, and/or radiation therapy. Thus, these tumors would be expected to be particularly prone to long-term digestive tract issues.

GI outcomes from selected cohort studies

Evidence (GI outcomes from selected cohort studies):

  1. Among 5-year childhood cancer survivors participating in the CCSS, the cumulative incidence of self-reported GI conditions was 37.6% at 20 years from cancer diagnosis (25.8% for upper GI complications and 15.5% for lower GI complications), representing an almost twofold excess risk of upper GI complications (relative risk [RR], 1.8; 95% CI, 1.6–2.0) and lower GI complications (RR, 1.9; 95% CI, 1.7–2.2), compared with sibling controls.[29]

    Factors predicting higher risk of specific GI complications include the following:

    • Older age at diagnosis.
    • Intensified therapy (anthracyclines for upper GI complications and alkylating agents for lower GI complications).
    • Abdominal radiation therapy.
    • Abdominal surgery.

Radiation-related GI injury

  • Late radiation injury to the digestive tract is attributable to vascular injury.
  • Necrosis, ulceration, stenosis, or perforation can occur and are characterized by malabsorption, pain, and recurrent episodes of bowel obstruction, as well as perforation and infection.[30,31,32]
  • In general, fractionated radiation doses of 20 Gy to 30 Gy can be delivered to the small bowel without significant long-term morbidity.[33]
  • Doses higher than 40 Gy are associated with a greater risk of bowel obstruction or chronic enterocolitis.[33]
  • Sensitizing chemotherapeutic agents such as dactinomycin or anthracyclines can increase this risk.

A limited number of reports describe GI complications in pediatric patients with genitourinary solid tumors treated with radiation therapy:

  1. The CCSS evaluated the long-term morbidity among unilateral, nonsyndromic Wilms tumor survivors (n = 2,008) according to conventional treatment regimens. All patients underwent unilateral nephrectomy.[34]
    • The 35-year cumulative incidence for intestinal obstruction was 8.1% (95% CI, 6.6%–9.6%).
    • Relative to siblings, survivors treated with vincristine and actinomycin D (VA) demonstrated an elevated risk of intestinal obstruction (RR, 9.4). The risk with VA treatment was lower than for treatment groups who received more intensive therapy (RR range, 15.4–46.8).
    • The rate of intestinal obstruction was highest among survivors who received more than 20 Gy of whole abdomen or flank radiation therapy.
  2. The CCSS evaluated the incidence and risk of late-occurring intestinal obstruction requiring surgery in 12,316 5-year survivors (2,002 with and 10,314 without abdominopelvic tumors) and 4,023 siblings.[35]
    • The most common diagnoses among survivors with abdominopelvic tumors were Wilms tumors and neuroblastomas but also included soft tissue sarcomas, lymphomas, and bone tumors.
    • The cumulative incidence of late intestinal obstruction requiring surgery at 35 years was 5.8% among survivors with abdominopelvic tumors, 1.0% among those without abdominopelvic tumors, and 0.3% among siblings.
    • Elevated risk of intestinal obstruction requiring surgery was associated with presence of an abdominopelvic tumor (adjusted rate ratio [ARR], 3.6; P < .001) and exposure to abdominal or pelvic radiation therapy within 5 years of cancer diagnosis (ARR, 2.4; P < .001).
    • Among survivors of abdominopelvic tumors, the median time from diagnosis to the first late intestinal obstruction requiring surgery was 12 years (range, 8–19 years).
    • Lymphoma resulted in the highest cumulative incidence of late-occurring intestinal obstruction that required surgery (7.2% at 35 years after diagnosis).
  3. The CCSS evaluated late-onset anorectal disease in cohort members:[36]
    • Among survivors, pelvic radiation therapy higher than 30 Gy within 5 years of cancer diagnosis was associated with late-onset anorectal disease (ARR for 30–49.9 Gy vs. none, 1.6; ARR for ≥50 Gy vs. none, 5.4).
    • The most frequent anorectal disease reported was fistula, followed by stricture and anorectal SMN.
    • Late-onset anorectal disease was associated with psychological impairment in all domains, as characterized by increased emotional distress and impaired quality of life.
  4. Reports from the Intergroup Rhabdomyosarcoma Study evaluating GI toxicity in long-term survivors of genitourinary rhabdomyosarcoma infrequently observed abnormalities of the irradiated bowel.[37,38,39]
    • Radiation-related complications occurred in approximately 10% of long-term survivors of paratesticular and bladder/prostate rhabdomyosarcoma and included intraperitoneal adhesions with bowel obstruction, chronic diarrhea, and stricture or enteric fistula formation.
  5. The CCSS evaluated the prevalence of esophageal stricture and identified associated clinical and treatment risk factors among 17,121 5-year childhood cancer survivors and 3,400 siblings.[40]
    • The prevalence of esophageal stricture among survivors was 2.0% (95% CI, 1.8%–2.2%), representing a 7.6-fold increased risk compared with siblings.
    • Factors significantly associated with risk of esophageal stricture included a diagnosis of Hodgkin lymphoma, greater chest radiation dose, younger age at cancer diagnosis, platinum chemotherapy exposure, and undergoing an HSCT.

Table 6 summarizes digestive tract late effects and the related health screenings.

Table 6. Digestive Tract Late Effectsa
Predisposing Therapy Gastrointestinal Effects Health Screening/Interventions
GVHD = graft-versus-host disease; HSCT = hematopoietic stem cell transplant; KUB = kidneys, ureter, bladder (plain abdominal radiograph).
a Adapted from theChildren's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers.
Radiation exposing esophagus; HSCT with any history of chronic GVHD Gastroesophageal reflux; esophageal dysmotility; esophageal stricture History: dysphagia, heart burn
Esophageal dilation, medical management, antireflux surgery
Radiation exposing bowel Chronic enterocolitis; fistula; strictures History: nausea, vomiting, abdominal pain, diarrhea
Serum protein and albumin levels yearly in patients with chronic diarrhea or fistula; gastroenterology consultation
Surgical and/or gastroenterology consultation for symptomatic patients
Radiation exposing bowel; laparotomy Bowel obstruction History: abdominal pain, distention, vomiting, constipation
Examination: tenderness, abdominal guarding, distension (acute episode)
Clinical evaluation in patients with symptoms of obstruction
Surgical consultation in patients unresponsive to medical management
Pelvic surgery; cystectomy Fecal incontinence History: chronic constipation, fecal soiling
Rectal examination

Hepatobiliary

Overview

Hepatic complications resulting from childhood cancer therapy are observed primarily as acute treatment toxicities.[41] Because many chemotherapy agents and radiation are hepatotoxic, transient liver function anomalies are common during therapy. Severe acute hepatic complications rarely occur. Survivors of childhood cancer can occasionally exhibit long-standing hepatic injury.[42]

Some general concepts regarding hepatotoxicity related to childhood cancer include the following:

  • The risk of long-term hepatotoxicity is not well defined.
  • Children with primary liver tumors requiring significant liver resection, or even transplant, are at higher risk of liver injury.
  • Children receiving radiation therapy to the liver are at higher risk of liver injury.
  • Children undergoing bone marrow transplant are at higher risk of liver injury.

Certain factors, including the type of chemotherapy, the dose and extent of radiation exposure, the influence of surgical interventions, and the evolving impact of viral hepatitis and/or other infectious complication, need additional attention in future studies.

Types of hepatobiliary late effects

Asymptomatic elevation of liver enzymes is the most common hepatobiliary complication.

  • Asymptomatic elevation of liver enzymes. Liver injury related to treatment for childhood cancer is often asymptomatic and indolent in course. While elevated serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma glutamyltransferase (GGT) levels can reflect transient acute liver injury during chemotherapy, they are not predictive of late hepatic dysfunction or cirrhosis.
    • Dutch investigators observed hepatobiliary dysfunction in 8.7% of 1,362 long-term survivors (median follow-up, 12.4 years since diagnosis) evaluated by ALT for hepatocellular injury and GGT for biliary tract injury. Cases with a history of viral hepatitis and a history of veno-occlusive disease were excluded.[43]
      • Predictors for elevated ALT and GGT by multivariable analysis included treatment with radiation therapy involving the liver, higher body mass index (BMI), higher alcohol intake, and longer follow-up time; older age at diagnosis was only significantly associated with elevated GGT levels.
    • An SJLIFE study evaluated prevalence of and risk factors for elevated ALT among 2,751 adult survivors of childhood cancer (median age, 31.4 years; median elapsed time from diagnosis, 23.2 years).[44]
      • ALT greater than sex-specific upper limits of normal was prevalent in 41.3% of survivors; however, the prevalence of grade 3 or 4 hepatic injury was infrequent (<1%).
      • Independent risk factors for elevated ALT included non-Hispanic White race and ethnicity, older age at evaluation, being overweight or affected by obesity, presence of metabolic syndrome, current treatment with a statin, hepatitis C infection, previous treatment with busulfan or thioguanine, history of hepatic surgery, and the percentage of liver treated with 10 Gy, 15 Gy, 20 Gy, or higher doses.

Less commonly reported hepatobiliary complications include the following:[45]

Cholelithiasis

  • In limited studies, an increased risk of cholelithiasis has been linked to ileal conduit, parenteral nutrition, abdominal surgery, abdominal radiation therapy, and HSCT.[46,47]
  • The cumulative incidence of late (occurring 5 or more years after cancer diagnosis) cholecystectomy among 25,549 CCSS participants diagnosed between 1970 and 1999 (median follow-up, 21.9 years) was 7.2% compared with 6.6% in a sibling control group (rate ratio, 1.3; 95% CI, 1.1–1.5).[48]
  • Independent risk factors for late cholecystectomy include attained age, female sex, increasing BMI, exposure to high-dose (>750 mg/m2) platinum chemotherapy (rate ratio, 2.6; 95% CI, 1.5–4.5), vinca alkaloid chemotherapy (rate ratio, 1.4; 95% CI, 1.1–1.8) or TBI (rate ratio, 2.2; 95% CI, 1.2–2.4).[48]

Focal nodular hyperplasia

  • Lesions made up of regenerating liver called focal nodular hyperplasia (FNH) have been incidentally noted on screening imaging studies after chemotherapy or HSCT.[49,50]
  • FNH is thought to represent iatrogenic benign manifestations of vascular damage and have been associated with veno-occlusive disease, high-dose alkylating agents (e.g., busulfan and melphalan), and liver irradiation.[49]
  • The prevalence of FNH is unknown; while noted at less than 1% in some papers,[50] this is likely an underestimate.
  • In one study of patients who were followed by magnetic resonance imaging (MRI) after transplant to assess liver iron stores, the cumulative incidence of FNH was 35% at 150 months posttransplant.[49]
  • FNH can mimic metastatic or subsequent tumors, but MRI imaging has a characteristic pattern and is generally diagnostic.[49]
  • Biopsy or resection is usually unnecessary unless the lesions grow or patients have worrisome symptoms.[49]

Nodular regenerative hyperplasia

  • Nodular regenerative hyperplasia is a rare condition characterized by the development of multiple monoacinar regenerative hepatic nodules and mild fibrosis.[45]
  • The pathogenesis of nodular regenerative hyperplasia is not well established but may represent a nonspecific tissue adaptation to heterogeneous hepatic blood flow.[51]
  • Nodular regenerative hyperplasia has rarely been observed in survivors of childhood cancer treated with chemotherapy, with or without liver irradiation.[52,53]
  • Biopsy may be necessary to distinguish nodular regenerative hyperplasia from a subsequent malignancy.[53]

Microvesicular fatty change

  • Histological evidence of fatty infiltration (93%) and siderosis (up to 70%) was observed in children with acute lymphoblastic leukemia (ALL) who recently completed intensified therapy. Fibrosis developed in 11% and was associated with higher serum low-density lipoprotein (LDL) cholesterol.[54]
  • Fatty liver with insulin resistance has also been reported to develop more frequently in long-term childhood cancer survivors treated with cranial radiation and TBI therapy with allogeneic HSCT without overweight or obesity.[55]
  • Prospective studies are needed to define whether acute posttherapy fatty liver change contributes to the development of late steatohepatitis or the metabolic syndrome in this population.

Acquired hemochromatosis

  • Red blood cell transfusion can result in an accumulation of excess iron caused by the disruption of the homeostasis of iron storage and distribution when exogenous iron is loaded into organs.
  • Transfusional iron overload has been reported in pediatric oncology patients, but its prevalence, organ distribution, and severity remain incompletely characterized.
  • MRI has emerged as an accurate, noninvasive means for measuring iron in multiple organ systems.[56,57]
  • In a cross-sectional study of 75 patients (4.4 years of median follow-up time; 4.9 years since last transfusion), MRI iron concentrations were elevated in the liver (49.3%) and pancreas (26.4%), but not in the heart.[56]
  • In a multivariable analysis, cumulative packed red blood cell volume and older age at diagnosis predicted elevated liver iron concentration.[56]
  • Receipt of allogeneic transplant is a significant risk factor for transfusional iron overload.[58]

Treatment-related risk factors for hepatobiliary late effects

The type and intensity of previous therapy influences risk for late-occurring hepatobiliary effects. In addition to the risk of treatment-related toxicity, recipients of HSCT frequently experience chronic liver dysfunction related to microvascular, immunologic, infectious, metabolic, and other toxic etiologies.

Key findings related to cancer treatment effect on hepatobiliary complications include the following:

Chemotherapy

  • Chemotherapeutic agents with established hepatotoxic potential include antimetabolite agents like 6-mercaptopurine, 6-thioguanine, methotrexate, and rarely, dactinomycin.
  • Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) and cholestatic disease have been observed after thiopurine administration, especially 6-thioguanine.[59]
  • Progressive fibrosis and portal hypertension have been reported in a subset of children who developed VOD/SOS after treatment with 6-thioguanine.[59]
  • Acute, dose-related, reversible VOD/SOS has been observed in children treated with dactinomycin for pediatric solid tumors.[60,61]
  • In the transplant setting, VOD/SOS has also been observed after conditioning regimens that have included cyclophosphamide/TBI, busulfan/cyclophosphamide, and carmustine/cyclophosphamide/etoposide.[62] High-dose cyclophosphamide, common to all of these regimens, is speculated to be a potential causative factor.

Radiation therapy

  • Acute radiation-induced liver disease also causes endothelial cell injury that is characteristic of VOD/SOS.[63]
  • In adults, the whole liver has tolerance up to 30 Gy to 35 Gy with conventional fractionation, the prevalence of radiation-induced liver disease varies from 6% to 66% based on the volume of liver involved and on hepatic reserve.[63,64]
  • Radiation hepatopathy after contemporary treatment appears to be uncommon in long-term survivors without predisposing conditions, such as viral hepatitis or iron overload.[65]
  • The risk of injury in children increases with radiation dose, hepatic volume, younger age at treatment, previous partial hepatectomy, and concomitant use of radiomimetic chemotherapy, such as dactinomycin and doxorubicin.[66,67,68,69]
  • Survivors who received radiation doses of 40 Gy to at least one-third of the liver volume, doses of 30 Gy or higher to the whole abdomen, or an upper abdominal field involving the entire liver are at highest risk for hepatic dysfunction.[42]
  • A PENTEC comprehensive review was performed to develop models to inform dose constraints for radiation-associated hepatic toxicity.[70]
    • In a model developed to calculate the risk of developing SOS after whole-liver radiation therapy, radiation dose and receipt of nonalkylating chemotherapy were significant. Age younger than 20 years at the time of radiation therapy was borderline significant.
    • The predicted risk of SOS was 2% with zero radiation therapy dose, 6.1% after treatment with 10 Gy, and 14.5% after treatment with 20 Gy to the whole liver.
    • Patients with Wilms tumor treated with right flank radiation therapy (estimated dose, 6.54 ± 2.50 Gy) had a higher observed rate of SOS than patients who received left flank radiation therapy (estimated dose, 2.16 ± 1.15 Gy).
    • Data were sparse regarding rates of late liver injury after radiation therapy, which suggests low rates of severe toxicity after treatment for common pediatric malignancies.

HSCT

  • Chronic liver dysfunction in patients after HSCT is multifactorial in etiology with the most common etiologies including iron overload, chronic GVHD, and viral hepatitis.[71]
  • Patients with chronic GVHD of the GI tract who exhibit an elevated bilirubin have a worse prognosis and quality of life.[72]
  • While chronic liver dysfunction may be seen in more than one-half of long-term HSCT survivors, and the course of the disease appears to be indolent, continued follow-up is needed to establish its long-term impact on survivor health.[73]

Infectious risk factors for hepatobiliary late effects

Viral hepatitis B and C may complicate the treatment course of childhood cancer and result in chronic hepatic dysfunction.

  • The incidence of transfusion-related hepatitis C in childhood cancer survivors has ranged from 5% to 50% depending on the geographic location of the reporting center.[74,75,76,77,78,79,80]
  • Chronic hepatitis predisposes the childhood cancer survivor to cirrhosis, end-stage liver disease, and hepatocellular carcinoma.[78,79]
  • Concurrent infection with hepatitis B and C in combination or in co-occurrence with other hepatotrophic viruses accelerates the progression of liver disease.[75,77]
  • Because most patients received some type of blood product during childhood cancer treatment and many are unaware of their transfusion history, screening on the basis of date of diagnosis/treatment is recommended.[81]
  • All survivors of childhood cancer who received treatment before 1972 should be screened for hepatitis B, and those who received treatment before 1993 should be screened for hepatitis C and referred for discussion of treatment options if screening results are positive.[81]

Posttherapy management

Survivors with liver dysfunction should be counseled regarding risk-reduction methods to prevent hepatic injury.

  • Standard recommendations include maintenance of a healthy body weight, abstinence from alcohol use, and immunization against hepatitis A and B viruses.[42]
  • In patients with chronic hepatitis, precautions to reduce viral transmission to household and sexual contacts should also be reviewed.

Table 7 summarizes hepatobiliary late effects and the related health screenings.

Table 7. Hepatobiliary Late Effectsa
Predisposing Therapy Hepatic Effects Health Screening/Interventions
ALT = alanine aminotransferase; AST = aspartate aminotransferase; HSCT = hematopoietic stem cell transplant.
a Adapted from theChildren's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers.
Methotrexate; mercaptopurine/thioguanine; HSCT Hepatic dysfunction Laboratory tests: ALT, AST, bilirubin levels
Ferritin in those treated with HSCT
Mercaptopurine/thioguanine; HSCT Veno-occlusive disease/sinusoidal obstructive syndrome Examination: scleral icterus, jaundice, ascites, hepatomegaly, splenomegaly
Laboratory tests: ALT, AST, bilirubin, platelet levels
Ferritin in those treated with HSCT
Radiation exposing liver/biliary tract; HSCT Hepatic fibrosis/cirrhosis; focal nodular hyperplasia Examination: jaundice, spider angiomas, palmar erythema, xanthomata, hepatomegaly, splenomegaly
Laboratory tests: ALT, AST, bilirubin levels
Ferritin in those treated with HSCT
Prothrombin time for evaluation of hepatic synthetic function in patients with abnormal liver screening tests
Screen for viral hepatitis in patients with persistently abnormal liver function or any patient transfused before 1993
Gastroenterology/hepatology consultation in patients with persistent liver dysfunction
Hepatitis A and B immunizations in patients lacking immunity
Consider phlebotomy and chelation therapy for iron overload
Radiation exposing liver/biliary tract Cholelithiasis History: colicky abdominal pain related to fatty food intake, excessive flatulence
Examination: right upper quadrant or epigastric tenderness (acute episode)
Consider gallbladder ultrasonography in patients with chronic abdominal pain

Pancreas

The pancreas has been thought to be relatively radioresistant because of a paucity of information about late pancreatic-related effects. However, children and young adults treated with TBI or abdominal irradiation are known to have an increased risk of insulin resistance and diabetes mellitus.[82,83,84]

While corticosteroids and asparaginase are associated with acute toxicity to the pancreas, late sequelae in the form of exocrine or endocrine pancreatic function for those who sustain acute injury have not been reported.

Evidence (risk of diabetes mellitus):

  1. The prevalence of prediabetes among survivors of childhood cancer, risk factors for progression to diabetes, and association between prediabetes and late cardiovascular events and chronic kidney disease were investigated using the SJLIFE cohort.[85]
    • The prevalence of prediabetes (defined as fasting plasma glucose level of 100–125 mg/dL or hemoglobin A1c of 5.7%–6.4%) was assessed in 3,529 adult survivors of childhood cancer. The prevalence of prediabetes in survivors (median age, 30 years) was 29.2%, and the prevalence of diabetes was 6.5%.
    • By age 40 to 49 years, the prevalence of prediabetes was 45.5%, and in each age strata, survivors had a significantly higher prevalence of prediabetes and diabetes than controls (P < .0025). Among the 695 survivors with prediabetes who underwent longitudinal follow-up, 10% progressed to diabetes.
    • Radiation exposure to the pancreatic tail was the only treatment that significantly increased the risk of prediabetes, independent of age, sex, race, BMI, physical activity, and other therapy exposures.
    • Compared with survivors with normal glucose control, adjusting for relevant treatment exposures, survivors with prediabetes were at an increased risk of future myocardial infarction (hazard ratio [HR], 2.4) and chronic kidney disease (HR, 2.9), while survivors with diabetes were also at an increased risk of future cardiomyopathy (HR, 3.8) and stroke (HR, 3.4).
  2. CCSS investigators evaluated the risk of diabetes mellitus among 20,762 5-year childhood cancer survivors and 4,853 siblings.[86]
    • Survivors exposed to abdominal radiation (n = 4,568) were almost three times more likely to develop diabetes than were siblings and 1.6 times more likely than survivors who were not exposed to abdominal radiation.
    • Among survivors treated with abdominal radiation therapy, multivariable modeling identified independent risk factors for developing diabetes, which included older attained age, higher BMI, and increasing dose to the pancreatic tail.
    • A significant interaction was also identified between younger age (<10 years) at cancer diagnosis and higher mean pancreatic tail dose.
  3. SJLIFE study investigators evaluated the prevalence of and risk factors for diabetes mellitus among 1,044 adult survivors of childhood ALL (mean age, 34 years) who were clinically assessed more than 10 years after treatment and 368 community controls (mean age, 35 years).[87]
    • Type 2 diabetes mellitus was prevalent in 7.5% of survivors and 3.8% of controls.
    • Independent risk factors for developing diabetes among survivors included older age (OR, 1.05 for each additional year), BMI of 30 kg/m2 or higher (OR, 7.4), and history of drug-induced hyperglycemia during therapy (OR, 4.67).
  4. A retrospective cohort study, based on self-reports of 2,520 5-year survivors of childhood cancer treated in France and the United Kingdom, investigated the relationship between radiation dose to the pancreas and risk of a subsequent diabetes mellitus diagnosis.[88]
    • Sixty-five cases of diabetes mellitus were validated; the risk increased with radiation therapy to the tail of the pancreas, where the islets of Langerhans are concentrated. Risk increased up to 20 to 29 Gy and then plateaued. The estimated RR at 1 Gy was 1.61.
    • Radiation dose to other parts of the pancreas did not have a significant effect.
    • Compared with patients who did not receive radiation therapy, the RR of diabetes mellitus was 11.5 in patients who received more than 10 Gy to the pancreas.
    • Children younger than 2 years at the time of radiation therapy were more sensitive than were older patients (RR at 1 Gy was 2.1 for the young age group vs. 1.4 for older patients).
    • For the 511 patients who received more than 10 Gy, the cumulative incidence of diabetes mellitus was 16%.
  5. Another study evaluated the risk of diabetes mellitus in 2,264 5-year survivors of Hodgkin lymphoma (42% younger than 25 years at diagnosis) after a median follow-up of 21.5 years.[89]
    • The cumulative incidence of diabetes mellitus was 8.3% (95% CI, 6.9%–9.8%) for the overall cohort and 14.2% (95% CI, 10.7%–18.3%) for those treated with more than 36 Gy para-aortic radiation.
    • Survivors treated with more than 36 Gy of radiation to the para-aortic lymph nodes and spleen had a 2.3-fold increased risk of diabetes mellitus compared with those who did not receive radiation therapy.
    • The risk of diabetes mellitus increased with higher doses to the pancreatic tail.

For digestive system late effects information, including risk factors, evaluation, and health counseling, see the Children's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers.

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Late Effects of the Endocrine System

Endocrine dysfunction is common among survivors of childhood cancer, especially in those who were treated with surgery or radiation therapy that involved hormone-producing organs and those who received alkylating agent chemotherapy.

Chart showing the prevalence of endocrine disorders at the last follow-up visit by gender.
Figure 6. Prevalence of endocrine disorders at the last follow-up visit, by sex. Brignardello E, Felicetti F, Castiglione A, et al.: Endocrine health conditions in adult survivors of childhood cancer: the need for specialized adult-focused follow-up clinics. European Journal of Endocrinology 168 (3): 465-472, 2013. Copyright © 2013, European Society of Endocrinology.

The prevalence of specific endocrine disorders is affected by the following:[1,2,3,4]

  • Patient factors (e.g., age at treatment and sex).
  • Tumor location (e.g., suprasellar and nonsuprasellar).[5]
  • Treatment factors (e.g., radiation dose and treatment volume).
  • Time from radiation exposure (typically increases with longer time from radiation exposure [see Figure 6]).[1]

Endocrinologic late effects can be broadly categorized as those resulting from hypothalamic-pituitary injury or from peripheral glandular compromise.[1,2,3,4] The former are most common after treatment for central nervous system (CNS) tumors. The prevalence of these late effects was 24.8% in a nationwide cohort study of 718 survivors who lived longer than 2 years and all hypothalamic-pituitary axes were affected.[3]

The following sections summarize research that characterizes the clinical features of survivors at risk of endocrine dysfunction that impacts pituitary, thyroid, adrenal, and gonadal function.

Thyroid Gland

  • Thyroid dysfunction is a common delayed effect after radiation therapy exposures to fields that include the thyroid gland. This type of radiation therapy is used in treating Hodgkin lymphoma, brain tumors, head and neck sarcomas, and acute lymphoblastic leukemia (ALL).
  • There is considerable evidence linking radiation exposure to thyroid abnormalities. However, the prevalence of specific conditions varies widely because studies are limited by cohort selection and participation bias, heterogeneity in radiation treatment approach, time since radiation exposure, and method of ascertainment (e.g., self-report vs. clinical or diagnostic imaging assessment).
  • Thyroid abnormalities observed in excess in childhood cancer survivors include the following:
    • Primary hypothyroidism.
    • Hyperthyroidism.
    • Goiter.
    • Nodules.

Hypothyroidism

Risk factors

Thyroid radiation therapy. An increased risk of hypothyroidism has been reported among childhood cancer survivors treated with head and neck radiation exposing the thyroid gland, especially among survivors of Hodgkin lymphoma.[1,2,3,4] Among survivors of head and neck tumors treated with radiation therapy potentially exposing the hypothalamic-pituitary region and the thyroid gland, hypothyroidism may result from thyrotropin-releasing hormone (TRH) and/or thyroid-stimulating hormone (TSH) deficiency (central hypothyroidism), thyroid gland dysfunction (primary hypothyroidism), or a combination of central and primary causes.

Iodine I 131-metaiodobenzylguanidine (131I-MIBG).

  • Therapeutic 131I-MIBG. Thyroid disorders, including primary hypothyroidism, have been reported in children with neuroblastoma who were treated with 131I-MIBG, despite thyroid protection with potassium iodide, perchlorate, or the combination of potassium iodide, thyroxine (T4), and a thiamazole. However, these reports feature small numbers of patients who have other treatment-related risk factors for thyroid disorders, which limits the ability to identify an independent effect of 131I-MIBG.[6] Thyroid disorders were diagnosed in 81% of survivors 15 years after treatment with 131I-MIBG.[7]
  • Diagnostic 131I-MIBG. Late-onset thyroid abnormalities have not been reported among childhood cancer survivors who had either 131I-MIBG or 123I-MIBG to monitor disease status.[8,9]
    • A retrospective cohort study (n = 48) assessed the prevalence of thyroid dysfunction in survivors of a neuroblastic tumor who received 123I-MIBG for diagnostic purposes. All patients received thyroid prophylaxis (potassium iodide or combination of potassium iodide, thiamazole, and T4) during exposure to 123I-MIBG. After a median follow up of 6.6 years, thyroid function was normal in 46 of the 48 survivors. Two survivors had mild thyroid dysfunction.[10]

Thyroidectomy. As observed in the general, noncancer population, partial or obviously subtotal surgical resection of the thyroid is a risk factor for subsequent hypothyroidism.[11,12,13]

Evidence (prevalence of and risk factors for hypothyroidism):

  1. The German Group of Paediatric Radiation Oncology reported on 1,086 patients treated at 62 centers, including 404 patients (median age, 10.9 years) who received radiation therapy to the thyroid and/or pituitary gland.[14] Follow-up information was available for 264 patients (60.9%; median follow-up, 40 months), with 60 patients (22.7%) showing pathological values.
    • Compared with patients treated with prophylactic cranial irradiation (median dose, 12 Gy), the hazard ratio (HR) for the development of pathological thyroid blood values was 3.072 (P = .002) for patients treated with radiation doses of 15 Gy to 25 Gy to the thyroid gland.
    • The HR was 3.769 (P = .009) for patients treated with more than 25 Gy of radiation to the thyroid gland. The HR was 5.674 (P < .001) for patients treated with craniospinal irradiation (CSI).
    • The cumulative incidence of thyroid hormone substitution therapy did not differ between defined subgroups.
  2. The Childhood Cancer Survivor Study (CCSS) investigated the prevalence of self-reported hypothyroidism assessed through serial questionnaires in 12,015 survivors. A total of 1,193 cases of hypothyroidism were observed, 777 (65%) of which occurred 5 or more years after a cancer diagnosis.[15]
    • The prevalence at 5 years after a cancer diagnosis and the incidence through 30 years after a cancer diagnosis was the highest in 5-year survivors of Hodgkin lymphoma (32.3%) and CNS tumors (17.7%).
    • The incidence was significantly associated with radiation dose to the thyroid and pituitary. The combined effects of thyroid and hypothalamic-pituitary doses appear to be less than additive when pituitary doses are greater than 16 Gy.
    • Radiation-related risks were higher in males than females and inversely associated with age at exposure and time since exposure but remained elevated more than 25 years after exposure.
    • Certain types of chemotherapy were significantly associated with the risk: bleomycin (rate ratio, 3.4), and the alkylating agents lomustine (rate ratio, 3.0) and cyclophosphamide (rate ratio, 1.3). The strongest chemotherapy-associated risk occurred among survivors of CNS cancer. A significant dose response for lomustine was observed (P < .01).
  3. In the CCSS, a cohort of childhood Hodgkin lymphoma survivors treated between 1970 and 1986 were evaluated for thyroid disease by use of a self-report questionnaire.[16]
    • Among 1,791 survivors who were followed for a median of 14 years, 34% reported that they had been diagnosed with at least one thyroid abnormality.
    • For hypothyroidism, there was a clear dose response, with a 20-year risk of:
      • 20% for those who received less than 35 Gy of radiation to the thyroid gland.
      • 30% for those who received 35 Gy to 44.9 Gy of radiation to the thyroid gland.
      • 50% for those who received more than 45 Gy of radiation to the thyroid gland.
    • Compared with a sibling control group, the relative risk (RR) was 17.1 for hypothyroidism.
    • Elapsed time since diagnosis was a risk factor for hypothyroidism, with the risk increasing in the first 3 to 5 years postdiagnosis.
    • Females were at increased risk for hypothyroidism.
  4. A follow-up study from the CCSS compared self-reported data from 14,290 survivors with data from 4,031 sibling controls.[2]
    • The RR was 3.8 for hypothyroidism and remained significantly higher in survivors when compared with controls, even in the absence of radiation therapy to the thyroid or pituitary.
    • These results indicate the need for continued and individualized long-term monitoring strategies in childhood cancer survivors.
  5. Continuous improvements in the precision of radiation therapy delivery carry the promise to decrease the radiation therapy dose received by the thyroid in a subset of patients. This was demonstrated in a study of 189 children and young adults (aged <26 years) with brain tumors treated with proton radiation therapy.[17]
    • At a median follow-up of 4.4 years, the cumulative incidence of primary hypothyroidism was 3% after CSI and 1.6% overall, which is substantially lower than previous reports of 56% to 65% incidence after CSI with photons.
  6. Among 118 survivors of medulloblastoma (median follow-up, 5.6 years), the estimated cumulative incidence of hypothyroidism was 35.8% (95% confidence interval [CI], 26.7%–47.1%) by 5 years after radiation therapy.[18]
    • The median time from the end of radiation therapy to the development of hypothyroidism was 2.1 years (range, 0.1–7.1 years) after proton radiation therapy and 2.9 years (range, 0.8–7.2 years) after photon radiation therapy.
    • The rate of hypothyroidism (HR, 2.36; 95% CI, 1.11–5.02) was higher among patients treated with photon radiation therapy compared with those treated with proton radiation therapy.
    • Differences in hypothyroidism risk by radiation modality were largely attributed to higher rates of primary hypothyroidism after photon radiation therapy (HR, 4.61; 95% CI, 1.20–17.66).
  7. St. Jude Life (SJLIFE) cohort study investigators evaluated the prevalence of and risk factors for primary hypothyroidism and its associations with chronic health conditions and quality of life among 2,965 childhood cancer survivors (median age, 30.9 years; median time postdiagnosis, 22.3 years).[13]
    • Primary hypothyroidism was prevalent in 14.7% of survivors. It was more common in females (odds ratio [OR], 1.06; 95% CI, 1.03–1.08) and survivors diagnosed older than 15 years (vs. age <5 years). It was less common in non-White survivors (OR, 0.96; 95% CI, 0.93–0.99).
    • Radiation therapy potentially exposing the thyroid gland was associated with dose-related risk of hypothyroidism.
    • Significant associations with primary hypothyroidism included frailty (OR, 1.54; 95% CI, 1.05–2.26), dyslipidemia (OR, 1.52; 95% CI, 1.14–2.04), and impaired physical quality of life (OR, 1.66; 95% CI, 1.12–2.48).
  8. The Pediatric Normal Tissue Effects in the Clinic (PENTEC) research consortium performed a systematic review of radiation-associated primary hypothyroidism in children younger than 21 years between 1970 and 2017.[19]
    • At mean doses of 10 Gy, 20 Gy, and 30 Gy, predicted rates of uncompensated (clinical) hypothyroidism were 4%, 7%, and 13%, respectively. The compensated (subclinical) hypothyroidism rates were 12%, 25% and 44%, respectively.
    • Female sex (RR, 1.7; P < .0001) and age younger than 15 years at the time of radiation therapy (RR, 1.3; P < .005) were associated with higher risks of hypothyroidism.
    • After a mean thyroid dose of 20 Gy, predicted rates of hypothyroidism were 13% for males younger than 14 years and more than 29% for females older than 15 years at the time of radiation therapy.
    Table 8. Risks of Hypothyroidism (Compensated or Uncompensated) After Radiation Therapy for Pediatric Malignancies, Grouped by Mean Thyroid Dose, Age, and Sexa
    Mean Thyroid Dose Risk of Hypothyroidismb
    Age <14 yc Age >15 yc
    Female Male Female Male
    a Adapted from Milano et al.[19]
    b Any hypothyroidism (i.e., compensated or uncompensated).
    c Age 14 to 15 y was used as a cutoff because the two studies that analyzed age used different cut-points. Presumably, the risks of hypothyroidism in patients irradiated at ages 14 to 15 y would be intermediate to those shown for ages <14 y and >15 y.
    10 Gy 10% 6% 14% 8%
    20 Gy 22% 13% 29% 17%
    30 Gy 39% 23% 53% 31%
    40 Gy 59% 35% 79% 47%
  9. The PENTEC research consortium performed a systematic review of radiation-associated hypothyroidism.[20]
    • Among seven cohorts (250 patients), the dose associated with a 50% risk (D50) of hypothyroidism was 39 Gy (95% CI, 34.1–53.2).
    • The risk was 20% for children who received a mean dose of 22 Gy in 2-Gy fractions.

Clinical presentation

  • Most children treated with radiation therapy who develop hypothyroidism do so within the first 2 to 5 years posttreatment, but new cases can occur later.
  • Reports of thyroid dysfunction differ depending on the dose of radiation, the length of follow-up, and the biochemical criteria used to make the diagnosis.[21]
  • The most frequently reported abnormalities include the following:
    • Elevated TSH.
    • Depressed T4.
    • Elevated TSH and depressed T4.
  • Central hypothyroidism results from radiation exposure of the hypothalamic pituitary axis; there is typically a low free T4 in conjunction with low TSH.
  • Compensated hypothyroidism includes an elevated TSH with a normal T4 and is asymptomatic. The natural history is unclear, but most endocrinologists support treatment.
  • Uncompensated hypothyroidism includes both an elevated TSH and a depressed T4.
  • Thyroid hormone replacement is beneficial for correction of the metabolic abnormality, and has clinical benefits for cardiovascular, gastrointestinal, and neurocognitive function.

Hyperthyroidism

While less common than hypothyroidism, childhood cancer survivors also experience an increased risk of hyperthyroidism.[2,16,22,23]

Evidence (prevalence of and risk factors for hyperthyroidism):

  1. CCSS investigators evaluated the prevalence of thyroid disease among 1,791 childhood Hodgkin lymphoma survivors treated between 1970 and 1986 and followed for a median of 14 years.[16]
    • Hyperthyroidism was reported by 5% of survivors, which was eightfold greater than the incidence reported by the controls.
    • Radiation dose of 35 Gy or more to the thyroid was the only risk factor identified for hyperthyroidism.
  2. Another CCSS study evaluated the risk of hyperthyroidism in relation to incidental therapeutic radiation dose to the thyroid and pituitary glands.[22]
    • Hyperthyroidism was self-reported by 179 survivors, with 148 cases diagnosed 5 or more years after cancer diagnosis.
    • The cumulative proportion of survivors with hyperthyroidism by 30 years after cancer diagnosis was 2.5% (95% CI, 2.0%–2.9%).
    • Thyroid radiation increased the risk of hyperthyroidism with evidence of a linear thyroid radiation dose-response over the dose range of 0 Gy to 63 Gy.
    • Radiation to the pituitary gland and chemotherapy were not significantly associated with hyperthyroidism.
    • Radiation-associated risk of hyperthyroidism remained elevated longer than 25 years after exposure.

Thyroid nodules

The clinical manifestation of thyroid neoplasia among childhood cancer survivors ranges from asymptomatic, small, solitary nodules to large, intrathoracic goiters that compress adjacent structures.

The following factors are linked to an increased risk of thyroid nodule development:

  • Radiation dose, time from diagnosis, and female sex.
    • Any radiation field that includes the thyroid is associated with an excess risk of thyroid neoplasms, which may be benign (usually adenomas) or malignant (most often differentiated papillary carcinoma).[2,16,24,25,26,27]
    • A CCSS study that included survivors of Hodgkin lymphoma identified time from diagnosis, female sex, and radiation dose of 25 Gy or higher as significant risk factors for thyroid nodule development.[16]
    • Based on a cohort of 3,254 2-year childhood cancer survivors treated before 1986 and monitored for 25 years, the risk of thyroid adenoma increased with the size of the radiation dose to the thyroid during childhood cancer treatment and plateaued at doses exceeding 10 Gy.[25]
    • CCSS investigators performed a nested case-control study to evaluate the magnitude of risk for thyroid cancer over the therapeutic radiation dose range of pediatric cancers. The risk of thyroid cancer increased with radiation doses up to 20 Gy to 29 Gy (OR, 9.8; 95% CI, 3.2–34.8), but declined at doses higher than 30 Gy, consistent with a cell-killing effect.[27]
  • Age at time of radiation therapy.
    • Based on the same cohort of 3,254 2-year childhood cancer survivors, the risk of thyroid adenoma per unit of radiation dose to the thyroid was higher if radiation therapy had been delivered before age 5 years. The risk was also higher in individuals who were younger than 40 years at the time of the study.[25]
    • Younger age at time of radiation therapy has also been linked to an excess risk of thyroid carcinoma.[24,25,26,27]
  • Exposure to 131I-MIBG.
    • During childhood and adolescence, there is an increased risk of developing thyroid nodules, and potentially thyroid cancer, in patients exposed to 131I-MIBG.
    • Clinicians caring for survivors treated with 131I-MIBG should be aware of the risks of developing thyroid dysfunction, thyroid nodules, and thyroid cancer.[28]
  • Chemotherapy.
    • An increased risk of thyroid nodules and cancer has also been observed in association with chemotherapy, independent of radiation exposure.[2,24,25]
    • In a pooled study of two cohorts of 16,757 survivors that included 187 patients with secondary thyroid cancer, treatments with alkylating agents, anthracyclines, or bleomycin were associated with a significantly increased risk of thyroid cancer in individuals not exposed to radiation therapy.[29]
    • In the CCSS, the rate ratio of developing thyroid cancer was 2.5 (P < .01) in survivors not treated with thyroid radiation when compared with sibling controls.[2]
    • Areas of active research include defining the precise role of exposure to chemotherapy and developing risk prediction models for thyroid cancer in childhood cancer survivors on the basis of demographic and treatment-related risk factors.[30]

Screening for thyroid cancer

  • Several studies have demonstrated that ultrasonography is superior to clinical examination for detecting thyroid nodules and thyroid cancers, and they have characterized ultrasonographic features of nodules that are more likely to be malignant.[31,32,33]
  • Primary screening for thyroid neoplasia (beyond physical examination with thyroid palpation) remains controversial because of the lack of data indicating a survival benefit and quality-of-life benefit associated with early detection and intervention.[34]
  • Because these lesions tend to be indolent, are rarely life-threatening, and may clinically manifest many years after exposure to radiation, there are significant concerns regarding the costs and harms of overscreening.[35]
  • Expert panels have refrained from specifically endorsing or discouraging the use of ultrasonography as a screening tool for thyroid cancer and this continues to be an active area of investigation.[36]
  • Following a systematic assessment of the evidence, the International Guideline Harmonization Group concluded that initiation of surveillance and the type of surveillance modality (thyroid palpation vs. ultrasonography) should be determined by shared decision-making between the health care provider and survivor after carefully considering the benefits and harms. A decision aid to facilitate discussion accompanies their recommendations.[34]

For information about subsequent thyroid cancers, see the Subsequent Neoplasms section.

Posttransplant thyroid dysfunction

Survivors of pediatric hematopoietic stem cell transplant (HSCT) are at increased risk of thyroid dysfunction.[37,38]

  • In a retrospective study of a single pediatric transplant unit, 244 pediatric patients were observed over a 20-year period. These patients had undergone HSCT for malignant or nonmalignant diseases between 1999 and 2018. Patients were assessed with a minimum of four thyroid function tests and one or more thyroid ultrasounds sequentially after HSCT.[38]
    • Thyroid complications were detected in 19.7% of patients.
    • The 15-year cumulative incidence of either autoimmune or nonautoimmune thyroid dysfunctions (34%) did not differ statistically between patients who received total-body irradiation (TBI)–based regimens and patients who received chemotherapy-based regimens (P = .23). The cumulative incidence after busulfan-based conditioning was similar to that of TBI (10-year cumulative incidence, 22.2% vs. 25.9%, respectively).
    • The cumulative incidence of nonautoimmune hypothyroidism was statistically higher after busulfan-based conditioning (12.4%) than after other chemotherapy-only–based conditioning regimens (3.1%; P = .02, 5-year cumulative incidence).
    • The overall incidence of thyroid nodules was low for the first 5 years after HSCT (1.9%) but increased steeply over time, with a 15-year cumulative incidence as high as 52.1%. Patients who received TBI-based conditioning regimens had a higher 15-year cumulative incidence of nodules (66.8%) than patients who received chemotherapy-only regimens (33.6%; P = .02).
    • Age older than 10 years at transplant showed a protective effect (HR, 0.42).
    • Sonographic follow-up showed a progressive statistically significant reduction in thyroid anteroposterior diameter among patients who received TBI-based conditioning regimens (P = .005) but not in those who received chemotherapy-only regimens.
  • In a report from the Fred Hutchinson Cancer Research Center, the risk of thyroid dysfunction after HSCT was much lower (15%–16%) after fractionated TBI, as opposed to single-dose TBI (46%–48%).[37]
    • The increased risk of thyroid dysfunction did not differ between children receiving a TBI-based or busulfan-based regimen (P = .48).
    • Other high-dose therapies have not been studied.

TSH deficiency (central hypothyroidism) is discussed with late effects that affect the pituitary gland.

Table 9 summarizes thyroid late effects and the related health screenings.

Table 9. Thyroid Late Effectsa
Predisposing Therapy Endocrine/Metabolic Effects Health Screening
131I-MIBG = Iodine I 131-metaiodobenzylguanidine; T4 = thyroxine; TSH = thyroid-stimulating hormone.
a Adapted from theChildren's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers.
Radiation exposing thyroid gland; thyroidectomy Primary hypothyroidism TSH level
Radiation exposing thyroid gland Hyperthyroidism Free T4 level
TSH level
Radiation exposing thyroid gland, including 131I-MIBG Thyroid nodules Thyroid examination
Thyroid ultrasonography

Hypothalamus-Pituitary Axis

Survivors of childhood cancer are at risk of developing a spectrum of neuroendocrine abnormalities, primarily because of the effect of radiation therapy on the hypothalamus.

  • There are two categories of childhood cancer survivors who experience hypothalamus-pituitary dysfunction after radiation—survivors with a CNS tumor and survivors treated for a non-CNS tumor of the head or neck or leukemia and/or individuals with a history of an HSCT.[39]
  • In addition, tumor development or surgical resection close to the hypothalamus and/or pituitary gland may induce direct anatomical damage to these structures and result in hypothalamic-pituitary dysfunction.
  • Essentially all of the hypothalamic-pituitary axes are at risk.[40,41,42]

The quality of the literature regarding pituitary endocrinopathy among childhood cancer survivors is often limited by retrospective data collection, small sample size, cohort selection and participation bias, heterogeneity in treatment approach, time since treatment, and method of ascertainment. However, the evidence linking this outcome with radiation therapy, surgery, and tumor infiltration is compelling because affected individuals typically present with metabolic and developmental abnormalities early in follow-up.

The risk of hypothalamus-pituitary dysfunction increases with higher doses of radiation therapy. When the radiation therapy dose exceeds 30 Gy, there is a higher risk of developing hypothalamus-pituitary disorders, including adrenocorticotropic hormone (ACTH) deficiency, luteinizing hormone (LH)/follicle-stimulating hormone (FSH) deficiency, and TSH deficiency.[39]

Central diabetes insipidus

Central diabetes insipidus may herald the diagnosis of craniopharyngioma, suprasellar germ cell tumor, or Langerhans cell histiocytosis.[43,44,45]

  • Diabetes insipidus may occur as an isolated pituitary deficiency at presentation of sellar/suprasellar tumors, although additional pituitary hormone deficiencies may develop with tumor progression.
  • More commonly, diabetes insipidus occurs in the context of panhypopituitarism caused by the effects of the tumor on the hypothalamic-pituitary-adrenal (HPA) axis, or as a consequence of surgical procedures undertaken for local tumor control.
  • Central diabetes insipidus is unlikely to occur as a late effect from surgical tumor resection past 2 years of follow-up.[46] Its emergence past that time should prompt assessment for tumor changes or other causes.
  • Central diabetes insipidus has not been reported as a late effect of cranial irradiation in childhood cancer survivors.[3]

Anterior pituitary hormone deficiency

Deficiencies of anterior pituitary hormones and major hypothalamic regulatory factors are common late effects among survivors treated with cranial irradiation.[42]

Evidence (prevalence of anterior pituitary hormone deficiency):

  1. Young patients with brain tumors are particularly vulnerable to hypothalamic-pituitary dysfunction. One study included 718 childhood brain tumor survivors who were monitored for a median of 7.9 years.[47]
    • No differences were observed in the prevalence of hypothalamic-pituitary dysfunction among infants (0–1 years), toddlers (≥1–3 years), or older age groups at diagnosis, despite the fact that radiation therapy was less frequently used in infants.
    • Radiation exposure (OR, 16.44; 95% CI, 8.93–30.27), suprasellar tumor location (OR, 44.76; 95% CI, 19.00–105.49), and younger age (OR, 1.11; 95% CI, 1.05–1.18) were associated with hypothalamic dysfunction.
    • Infant and toddler brain tumor survivors showed more weight gain (P < .0001) and smaller height standard deviation score (SDS) (P = .001) during follow-up than survivors diagnosed at an older age.
    • Among non-irradiated survivors, those who were infants and toddlers at diagnosis were significantly more frequently diagnosed with TSH, ACTH, and antidiuretic hormone (ADH) deficiency, compared with survivors diagnosed at an older age, presumably caused by systemic therapies or the trauma of neurosurgery.
  2. A study targeting more refined data on the radiation doses associated with pituitary insufficiency analyzed 102 patients treated for tumors that included radiation therapy exposures (CNS, head and neck, hematologic malignancies) between 2008 and 2019. The median (interquartile range [IQR]) age at radiation therapy was 9.0 years (6.0–12.0 years), and the median follow-up was 5.7 years (3.5–9.1 years). Most patients received focal brain radiation therapy (36.3%) or TBI (32.4%). The most frequent diagnoses were ALL (25.5%) and medulloblastoma (17.6%).[48]
    • Most patients developed pituitary insufficiency (64 patients; 62.7%). Forty-one percent of patients had one hormone deficiency and 38% had two hormone deficiencies.
    • Growth hormone deficiency (58 patients; 56.9%) and TSH deficiency (32 patients; 31.4%) were most common.
    • Patients who developed pituitary insufficiency had received a higher maximum pituitary dose (median [IQR], 44.0 Gy [20.4–54.0] vs. 18.2 Gy [14.4–52.6]; P = .008). Doses of 40 to 49 Gy or higher than 50 Gy led to a higher cumulative incidence rate than doses lower than 20 Gy (HR, 4.07; P < .001 and HR, 3.04; P < .001, respectively).
    • However, even at lower dose bands, levels of pituitary insufficiency were significant. The 5-year cumulative incidence was higher than 30% for growth hormone deficiency with doses lower than 20 Gy and for TSH deficiency with doses of 20 to 29 Gy.
  3. In a single-institution study, 1,713 adult survivors of childhood cancers and brain tumors (median age, 32 years) were monitored for a median follow-up of 25 years.[41]
    • The prevalence of hypothalamic-pituitary axis disorders was 56.4% in individuals exposed to cranial radiation therapy at doses of 18 Gy or higher.
  4. A study of 3,141 childhood cancer survivors who were systematically evaluated for hypothalamic-pituitary disorders at a median follow-up of 24.1 years reported the following:[49]
    1. For patients who were treated with hypothalamic-pituitary radiation therapy (n = 1,089), the following was observed:
      • The estimated prevalence of growth hormone deficiency was 40.2%.
      • The estimated prevalence of TSH deficiency was 11.1%.
      • The estimated prevalence of LH/FSH deficiency was 10.6%.
      • The estimated prevalence of ACTH deficiency was 3.2%.
      • The estimated prevalence of central precocious puberty was 0.9%.
    2. For patients who did not receive hypothalamic-pituitary radiation therapy, the estimated prevalence of growth hormone deficiency was 6.2% and less than 1% for the other hypothalamic-pituitary disorders.
    3. Clinical factors independently associated with hypothalamic-pituitary disorders included the following:
      • Hypothalamic-pituitary radiation therapy (even at relatively low doses, except for ACTH deficiency which was not observed until >30 Gy).
      • Alkylating agents (growth hormone deficiency, LH/FSH deficiency).
      • Intrathecal chemotherapy (growth hormone deficiency).
      • Hydrocephalus with shunt placement (growth hormone deficiency, LH/FSH deficiency).
      • Seizures (TSH deficiency, ACTH deficiency).
      • Stroke (growth hormone deficiency, TSH deficiency, LH/FSH deficiency, ACTH deficiency).
    4. Adverse outcomes associated with hypothalamic-pituitary disorders included the following:
      • Short stature (growth hormone deficiency, TSH deficiency).
      • Severe bone mineral deficit (growth hormone deficiency, LH/FSH deficiency).
      • Obesity (LH/FSH deficiency).
      • Frailty (growth hormone deficiency).
      • Impaired physical health-related quality of life (TSH deficiency).
      • Sexual dysfunction (LH/FSH deficiency).
      • Impaired memory and processing speed (growth hormone deficiency, TSH deficiency).

The International Late Effects of Childhood Cancer Guideline Harmonization Group (IGHG) consisting of 42 interdisciplinary international experts performed a systematic literature search on hypothalamic-pituitary axis surveillance in childhood cancer survivors.[39]

  • They noted that hypothalamic-pituitary axis radiation exposure increased the risk for hypothalamic-pituitary dysfunction, with a dose dependent relationship. Doses of radiation therapy higher than 18 Gy are associated with a higher risk for growth hormone deficiency and central precocious puberty.
  • Deficiencies in ACTH, TSH, and LH/FSH generally occur after doses higher than 30 Gy.
  • The panel noted that childhood cancer survivors who have had local tissue injury to the hypothalamic-pituitary region are at risk of developing hypothalamic-pituitary dysfunction from the time of diagnosis or surgery for a brain tumor located near or within the hypothalamic-pituitary region or from occurrence of hydrocephalus (specifically at risk for growth hormone deficiency and central precocious puberty).
  • Individuals exposed to radiation are at risk of developing hypothalamic-pituitary dysfunction one year from completion of radiation therapy.
  • Childhood cancer survivors remain particularly at risk of growth hormone deficiency for at least 15 years after cancer diagnosis or treatment exposure. The risk beyond 15 years depends on individual patient factors. For central precocious puberty, patients remain at risk until age 8 years in girls and age 9 years for boys.

The six anterior pituitary hormones and their major hypothalamic regulatory factors are outlined in Table 10.

Table 10. Anterior Pituitary Hormones and Major Hypothalamic Regulatory Factors
Pituitary Hormone Hypothalamic Factor Hypothalamic Regulation of the Pituitary Hormone
(–) = inhibitory; (+) = stimulatory.
Growth hormone (GH) GH-releasing hormone +
Somatostatin
Prolactin Dopamine
Luteinizing hormone (LH) Gonadotropin-releasing hormone +
Follicle-stimulating hormone (FSH) Gonadotropin-releasing hormone +
Thyroid-stimulating hormone (TSH) Thyroid-releasing hormone +
Somatostatin
Adrenocorticotropic hormone (ACTH) Corticotropin-releasing hormone +
Vasopressin +

Growth hormone deficiency

Growth hormone deficiency is the most common and often the first anterior pituitary deficit to occur after cranial radiation therapy. In childhood survivors of CNS tumors, the overall prevalence of growth hormone deficiency is 12.5%.[3]

  • The risk increases with radiation dose and time since treatment.
  • Growth hormone deficiency can result from relatively low doses of cranial radiation.[50]
  • Growth hormone deficiency can develop after 18 Gy to 24 Gy of cranial radiation, which is used to treat patients with ALL and lymphoma. The higher the radiation dose, the earlier that growth hormone deficiency will occur after treatment.[51]
  • Approximately 60% to 80% of pediatric patients with brain tumors who received radiation therapy doses higher than 30 Gy will have impaired serum growth hormone response to provocative stimulation, usually within 5 years of treatment.[52,53]

Evidence (radiation-dose response relationship of growth hormone deficiency in childhood brain tumor survivors):

  1. In a report of 156 patients with medulloblastoma who were treated from 2003 to 2013 in the SJMB03 study, the following was observed:[54]
    • The 5-year cumulative incidence of growth hormone deficiency was 68.9%, and the cumulative incidence of growth hormone replacement was 48.1%.
    • Growth hormone deficiency was associated with increased hypothalamus dose (HR, 1.035; P = .0055) in average-risk patients and in high-risk patients who had a cerebrospinal fluid shunt (HR, 2.532; P = .0049).
  2. A study of conformal radiation therapy (CRT) in children with CNS tumors indicates that growth hormone insufficiency can usually be demonstrated within 12 months of radiation therapy, depending on hypothalamic dose-volume effects.[55]
  3. In a report featuring data from 118 patients with localized brain tumors who were treated with radiation therapy, peak growth hormone was modeled as an exponential function of time after CRT and mean radiation dose to the hypothalamus.[53]
    • The average patient was predicted to develop growth hormone deficiency with the following combinations of time after CRT and mean dose to the hypothalamus: 12 months and more than 60 Gy; 36 months and 25 Gy to 30 Gy; and 60 months and 15 Gy to 20 Gy.
    • A cumulative dose of 16.1 Gy to the hypothalamus would be considered the mean radiation dose causing a 50% risk of growth hormone deficiency at 5 years (TD50/5) (see Figure 7).

    Graph shows peak growth hormone (in ng/mL) according to hypothalamic mean dose and time (in months) after start of irradiation.
    Figure 7. Peak growth hormone (GH) according to hypothalamic mean dose and time after start of radiation. According to equation 2, peak GH = exp{2.5947 + time × [0.0019 − (0.00079 × mean dose)]}. Thomas E. Merchant, Susan R. Rose, Christina Bosley, Shengjie Wu, Xiaoping Xiong, and Robert H. Lustig, Growth Hormone Secretion After Conformal Radiation Therapy in Pediatric Patients With Localized Brain Tumors, Journal of Clinical Oncology, volume 29, issue 36, pages 4776-4780. Reprinted with permission. © (2011) American Society of Clinical Oncology. All rights reserved.

  4. A PENTEC review reported on the risk of growth hormone deficiency for childhood cancer survivors treated with radiation therapy.[20]
    • The normal tissue complication probability modeling for growth hormone deficiency (18 cohorts, 545 patients) found that the D50 was 24.9 Gy (95% CI, 20.9–28.0).
    • The normal tissue complication probability model fit for whole-brain irradiation in children with a median age of older than 5 years indicated a 20% risk of growth hormone deficiency for patients who received a mean dose of 21 Gy in 2-Gy fractions to the hypothalamic-pituitary axis.

Evidence (risk of growth deficits in childhood cancer survivors):

  1. One study evaluated 127 patients with ALL treated with 24 Gy, 18 Gy, or no cranial radiation therapy (treatment era, 1980s–1990s).[56]
    • The change in height, compared with population norms expressed as the SDS, was significant for all three groups. The dose response was -0.49 ± 0.14 for the group that did not receive radiation therapy, -0.65 ± 0.15 for the group that received 18 Gy of radiation therapy, and -1.38 ± 0.16 for the group that received 24 Gy of radiation therapy.
  2. Survivors of childhood ALL who are treated with chemotherapy alone are also at increased risk for adult short stature, although the risk is highest for those treated with cranial and craniospinal radiation therapy at a young age.[57] In a cross-sectional study, attained adult height was determined for 2,434 ALL survivors participating in the CCSS.
    • All survivor treatment exposure groups (chemotherapy alone and chemotherapy with cranial or craniospinal radiation therapy) had decreased adult height and an increased risk of adult short stature (height SDS < -2), compared with siblings (P < .001).
    • Compared with siblings, the risk of short stature for survivors treated with chemotherapy alone was elevated (OR, 3.4; 95% CI, 1.9–6.0).
    • Among survivors, significant risk factors for short stature included diagnosis of ALL before puberty, higher-dose cranial radiation therapy (≥20 Gy vs. <20 Gy), any radiation therapy to the spine (which effects vertebral bodies), and female sex.
  3. The impact of chemotherapy alone on growth in 67 survivors treated with contemporary regimens for ALL was statistically significant at -0.59 SD. The loss of growth potential did not correlate with growth hormone status in this study, further highlighting the participation of other factors in the growth impairments observed in this population.[58]
  4. In a longitudinal study of 372 survivors of ALL who were treated on a single-institution chemotherapy-only trial, the following were observed:[59]
    • Height z-scores declined during treatment and improved after therapy.
    • Younger age at diagnosis (2 to <10 years), low-risk ALL status, white blood cell count below 50 × 109 /L at diagnosis, or CNS-negative status were associated with significant improvements in z-scores for height during the off-therapy period compared with those older at diagnosis (age ≥10 years), those with standard-risk/high-risk ALL status, those with a white blood cell count of 50 × 109 /L or higher, or CNS-positive status.
    • The loss in height potential in older patients was attributed to attenuation of the growth spurt during treatment without improvement after therapy and to chemotherapy intensity in patients with standard- or high-risk disease features.
  5. A French CCSS study evaluated risk factors for short adult height and growth hormone deficiency in 2,965 childhood cancer survivors using clinical and treatment data available in medical records. Patients treated with growth hormones (6.4%) were excluded.[60]
    • Independent risk factors for short adult height included being young at the time of cancer treatment (RR, 0.9 per year of age), having a short height at diagnosis (≤2 SDS: RR, 6.7), and having received treatment with pituitary radiation (5–20 Gy: RR, 4.2; 20–40 Gy: RR, 10.2; ≥40 Gy: RR, 19.5), busulfan (RR, 4.5), or more than 300 mg/m2 of lomustine (300–600 mg/m2: RR, 4.2 and ≥600 mg/m2: RR, 9.1).
    • Children who were treated with 15 Gy or higher of radiation to 90% or more volume of seven or more vertebrae without pituitary irradiation had an increased risk of short adult stature (RR, 4.6). This risk increased by 1.3-fold to 2.4-fold if they also received pituitary radiation therapy.
  6. A St. Jude Children's Research Hospital investigation evaluated long-term (median follow-up, 10.2 years) height outcomes among 212 pediatric patients with CNS embryonal tumors who were treated with CSI at 23.4 Gy (n = 147) or 36 Gy or higher (n = 65).[61]
    • Compared with U.S. standards, mean final height z-scores at age 18 years were -1.3 for female and -1.5 for male survivors.
    • Factors associated with risk of height impairment included younger age at the time of CSI, higher CSI dose, and female sex.
    • Factors associated with higher growth rates before the age of 15 years included older age at CSI, male sex, CSI dose lower than 36 Gy, replacement therapy for growth hormone and central adrenal insufficiency, and White race.

Growth after hematopoietic stem cell transplant (HSCT)

  • Children who undergo HSCT with TBI have a significant risk of both growth hormone deficiency and the direct effects of radiation on skeletal development.[62,63,64]
  • The risk of growth hormone deficiency is increased with single-dose TBI as opposed to fractionated TBI, pretransplant cranial irradiation, female sex, and posttreatment complications such as graft-versus-host disease (GVHD).[62,63,64]
  • Hyperfractionation of the TBI dose markedly reduces risk in patients who have not undergone cranial irradiation for CNS leukemia prophylaxis or therapy.[65]
  • Regimens containing busulfan and cyclophosphamide appear to increase risk in some studies,[64,66] but not others.[67]

Evidence (growth hormone deficiency in childhood HSCT survivors):

  1. The late effects that occur after HSCT have been studied by the Late Effects Working Party of the European Group for Blood and Marrow Transplantation. Among 181 patients with aplastic anemia, leukemias, and lymphomas who underwent HSCT before puberty, the following results were observed:[68,69]
    • An overall decrease in final height–SDS value was found, compared with height at transplant and genetic height. The mean loss of height is estimated to be approximately 1 height–SDS (6 cm), compared with the mean height at time of HSCT and mean genetic height.
    • The type of transplant, GVHD, and growth hormone or steroid treatment did not influence final height.
    • TBI (single-dose more than fractionated-dose radiation therapy), male sex, and young age at transplant were found to be major factors for long-term height loss.
    • Most patients (140 of 181) reached adult height within the normal range of the general population.
  2. Growth hormone deficiency has been reported after lower doses with a single fraction of 10 Gy and fractionated doses of 12 to 18 Gy of TBI.[70]

Growth hormone replacement therapy

  • Growth hormone replacement therapy provides the benefit of optimizing height outcomes among children who have not reached skeletal maturity.[42] The diagnosis requires specialized dynamic testing.[42,71]
  • Treatment with recombinant growth hormone (rGH) replacement therapy is generally delayed until 12 months after successful completion of cancer or brain tumor treatments and after a multidisciplinary discussion involving the prescribing pediatric endocrinologist, the primary oncologist, and other providers selected by the patient or family.[72]
  • Safety concerns pertaining to the use of rGH in childhood cancer survivors have primarily been related to the mitogenic potential of the growth hormone stimulating tumor growth in a population with an increased risk of second neoplasms.[73] Most studies that report these outcomes, however, are limited by selection bias and small sample size.

Evidence (subsequent neoplasm risk after growth hormone deficiency replacement therapy):

  1. One study evaluated 361 growth hormone–treated cancer survivors enrolled in the CCSS and compared risk of recurrence, risk of subsequent neoplasm, and risk of death among survivors who did and did not receive treatment with growth hormone.[74]
    • The RR of disease recurrence was 0.83 (95% CI, 0.37–1.86) for growth hormone–treated survivors.
    • Growth hormone–treated participants were diagnosed with 15 subsequent neoplasms, all solid tumors, for an overall RR of 3.21 (95% CI, 1.88–5.46). This was mainly due to a small excess number of subsequent neoplasms observed in survivors of acute leukemia.[74]
    • With prolonged follow-up, the elevation of subsequent cancer risk resulting from growth hormone diminished.[75]
    • Compared with survivors not treated with growth hormone, those who were treated had a twofold excess risk of developing a subsequent neoplasm (RR, 2.15; 95% CI, 1.33–3.47; P < .002). Meningiomas were the most commonly observed neoplasms (9 of 20 tumors).[74]
  2. A study from the CCSS reported on the risk of subsequent CNS neoplasms after a longer period of follow-up.[76]
    • The adjusted rate ratio of meningioma and gliomas in growth hormone–treated survivors of CNS tumors was 1.0 (95% CI, 0.6–1.8; P = .94), when compared with CNS tumor survivors who were not treated with growth hormone. This finding indicates negligible differences between the two groups for this particular risk.
  3. A review of existing data suggests that treatment with growth hormone is not associated with an increased risk of CNS tumor progression or recurrence, or new or recurrent leukemia.[77]

In general, the data addressing subsequent malignancies among childhood cancer survivors treated with growth hormone therapy should be interpreted with caution given the small number of events.[42,55,72,73,74,78,79]

As outlined in a consensus statement by the Growth Hormone Research Society, areas of uncertainty include the safety of growth hormone in children with cancer-predisposing conditions, its use in growth hormone–deficient children who are receiving maintenance therapy, and the overall benefit-risk ratio in adult survivors.[80]

Disorders of LH and FSH

  • Pubertal development can be adversely affected by cranial radiation therapy.
  • Doses higher than 18 Gy can result in central precocious puberty, while doses higher than 30 Gy to 40 Gy may result in LH/FSH deficiency.[49]

Central precocious puberty

Prevalence and risk factors

  • Central precocious puberty is among the most common hypothalamic-pituitary dysfunctions. The prevalence varies across studies because of study cohort composition and method of ascertainment.[3,81,82]
  • In the SJMB03 study, 156 children and adolescents with medulloblastoma were treated with surgery, risk-adapted photon craniospinal irradiation, and dose-intensive chemotherapy.[54]
    • The 5-year cumulative incidence of precocious puberty was 2.0%.
  • Children with CNS tumors within or near the hypothalamic-pituitary axis (including those with neurofibromatosis type 1) or those treated with cranial radiation are most vulnerable.[3]
    • In a study of 178 childhood brain tumor survivors (median follow-up, 6.6 years), precocious puberty developed in 12.2% of survivors, with a 5-year cumulative incidence of 4.0%.[3]
    • Central precocious puberty has been reported in children receiving cranial irradiation in doses of 18 Gy or higher.[81,83,84]
  • Hydrocephalus also increases the risk of central precocious puberty.[85]

Diagnosis

  • Central precocious puberty is defined by the onset of pubertal development before age 8 years in girls and 9 years in boys as a result of the premature activation of the hypothalamic-pituitary-gonadal axis.
  • Assessment of puberty cannot be performed using testicular volume measurements in boys exposed to chemotherapy or direct radiation to the testes, given the toxic effect of these treatments on germ cells and repercussions on gonadal size.[86]
  • The staging of puberty in males within this population relies on the presence of other signs of virilization, such as the presence of pubic hair and the measurement of morning plasma testosterone and LH levels.[86]

Treatment and outcomes associated with central precocious puberty

  • Aside from the adjustment and psychosocial challenges associated with early pubertal development, precocious puberty can lead to the rapid closure of the skeletal growth plates and short stature. This deleterious effect can be further potentiated by growth hormone deficiency.[81,86]
  • The increased growth velocity induced by pubertal development can mask concurrent growth hormone deficiency with seemingly normal growth velocity; this occurrence may mislead care providers.[86]
  • The impact of central precocious puberty on linear growth can be ascertained by assessing the degree of skeletal maturation (or bone age) using an x-ray of the left hand.[87]
  • Delaying the progression of puberty relies on the use of various gonadotropin-releasing hormone agonist preparations. This approach has been shown to improve growth prospects, especially when other pituitary abnormalities, including growth hormone deficiency, are concurrently treated.[42,88]

LH/FSH deficiency

  • LH/FSH deficiency (also referred to as hypogonadotropic hypogonadism) can manifest through pubertal delay (after age 13 years in girls and 14 years in boys), arrested puberty, or symptoms of decreased sex hormone production, depending on age and pubertal status at the time of diagnosis.
  • The risk of LH/FSH deficiency is highest among patients treated with cranial radiation at doses greater than or equal to 30 Gy. LH/FSH deficiency following the exposure to lower doses can occur at delayed time points.[4]
  • With higher doses of cranial radiation therapy (>35 Gy), deficiencies in LH/FSH can be seen, with a cumulative incidence of 10% to 20% at 5 to 10 years posttreatment.[4,85]
  • The treatment of LH/FSH deficiency relies on sex-hormone replacement therapy adjusted to age and pubertal status.[42]

TSH deficiency

TSH deficiency (also referred to as central hypothyroidism) in survivors of childhood cancer can have profound clinical consequences and be underappreciated. Among survivors of head and neck tumors treated with radiation therapy potentially exposing the hypothalamic-pituitary region and the thyroid gland, hypothyroidism may result from TRH and/or TSH deficiency (central hypothyroidism), thyroid gland dysfunction (primary hypothyroidism), or a combination of central and primary causes.

Prevalence and risk factors

  • The risk of TSH deficiency is highest among patients treated with cranial radiation at doses of 30 Gy or higher. TSH deficiency following the exposure to lower doses can occur at delayed time points.[4]
  • The cumulative incidence of TSH deficiency was 23% (± 8%) among embryonal brain tumor survivors treated with risk-adapted CSI, conformal primary site irradiation, and high-dose chemotherapy. Radiation dose to the hypothalamus in excess of 42 Gy is associated with an increased risk of developing TSH deficiency (44% ± 19% for a dose of ≥42 Gy and 11% ± 8% for a dose of <42 Gy).[89]
  • In a report of 156 children and adolescents with medulloblastoma who were treated with surgery, risk-adapted photon craniospinal irradiation, and dose-intensive chemotherapy between 2003 and 2013, the incidence of hypothyroidism was 48.4%.[54]
    • In average-risk patients, hypothyroidism was associated with younger age (HR, 0.902; P = .0070), hypothalamus dose (HR, 1.039; P = .0273), and thyroid dose (HR, 1.070; P = .0263). The mean radiation therapy dose was 34.8 Gy (standard deviation [SD], 7.5) to the hypothalamus and 17.4 Gy (SD, 5.4) to the thyroid.
    • In high-risk patients, hypothyroidism was associated with increased hypothalamus dose (HR, 1.068; P = .0671) and thyroid dose (HR, 1.050; P = .0515). The mean radiation therapy dose was 47.8 Gy (SD, 4.87) to the hypothalamus and 25.8 Gy (SD, 7.2) to the thyroid.
  • Among medulloblastoma survivors treated with photon (median follow-up, 9.6 years) or proton (median follow-up, 3.8 years) radiation therapy, primary hypothyroidism developed in 12 of 54 patients (22%) after photon radiation therapy and 3 of 41 patients (7%) after proton radiation therapy (HR, 2.1; P = .27). Central hypothyroidism (TSH deficiency) developed in 13 of 54 patients (24%) after photon radiation therapy and 4 of 41 patients (10%) after proton radiation therapy (HR, 2.16, P = .18).[90]
  • Among 118 medulloblastoma survivors (median follow-up, 5.6 years), the estimated cumulative incidence of hypothyroidism was 35.8% (95% CI, 26.7%–47.1%) by 5 years after radiation therapy.[18]
    • The median time from the end of radiation therapy to the development of hypothyroidism was 2.1 years (range, 0.1–7.1 years) after proton radiation therapy and 2.9 years (range, 0.8–7.2 years) after photon radiation therapy.
    • The rate of hypothyroidism (HR, 2.36; 95% CI, 1.11–5.02) was higher in patients treated with photon radiation therapy than in those treated with proton radiation therapy.
    • Differences in hypothyroidism risk by radiation modality were largely attributed to higher rates of primary hypothyroidism after photon radiation therapy (HR, 4.61; 95% CI, 1.20–17.66).
  • Patients with central hypothyroidism should undergo testing for other hypothalamic-pituitary deficiencies before thyroid replacement. Thyroid replacement can enhance the clearance of cortisol, which exacerbates any underlying adrenal insufficiency and contributes to the possibility of adrenal crisis.
  • In a study of 189 children and young adults (aged <26 years) with brain tumors who were treated with proton radiation therapy, the 4-year actuarial rate of hypothyroidism was 20.1%. Ninety percent of the cases were related to central TSH deficiency.[17]

Clinical presentation and diagnosis

  • Symptoms of central hypothyroidism (e.g., asthenia, edema, drowsiness, and skin dryness) may have a gradual onset and go unrecognized until thyroid replacement therapy is initiated.
  • In addition to delayed puberty and slow growth, hypothyroidism may cause fatigue, dry skin, constipation, increased sleep requirement, and cold intolerance.
  • Individuals with TSH deficiency usually have low plasma free T4 levels and either low or inappropriately normal TSH levels. Declining free T4 levels within the normal range may also be predictive of TSH deficiency. Clinicians should not hesitate to reassess survivors with this pattern of thyroid function, especially in the presence of symptoms of hypothyroidism.[91]
  • Mixed primary and central hypothyroidism can also occur because of separate injuries to the thyroid gland and the hypothalamus (e.g., radiation injury to both structures), leading to mildly elevated TSH values despite the contribution of hypothalamic-pituitary deficits to hypothyroidism in affected individuals.

Management of TSH deficiency

  • Thyroid hormone replacement therapy using levothyroxine represents the mainstay of treatment of TSH deficiency.
  • The dose of levothyroxine needs to be adjusted solely using plasma free T4 levels. The levels of TSH are expected to remain low during therapy, given the central nature of this deficiency.
  • Central hypothyroidism should not be treated before assessment of the functioning of other hypothalamic-pituitary deficiencies, because it could precipitate an adrenal crisis in patients with ACTH deficiency.

ACTH deficiency

Prevalence and risk factors

  • ACTH deficiency is less common than other neuroendocrine deficits but should be suspected in patients who have a history of brain tumors (regardless of therapy modality), cranial radiation therapy, growth hormone deficiency, or central hypothyroidism.[42,89,92,93]
  • ACTH deficiency develops almost exclusively in survivors previously exposed to hypothalamic-pituitary doses of 30 Gy or greater.
    • The cumulative incidence of ACTH deficiency was 38% (± 6%) among embryonal brain tumor survivors treated with risk-adapted CSI, conformal primary site irradiation, and high-dose chemotherapy. ACTH status was not affected by the dose of radiation therapy administered to the hypothalamus (median, 42.2 Gy for no ACTH deficiency vs. 41.3 Gy for ACTH deficiency).[89]
    • In a study of 189 children and young adults (aged <26 years) with brain tumors who were treated with proton radiation therapy, the 5-year actuarial rate of ACTH deficiency was 8%, occurring almost exclusively after ≥40 Gy to the hypothalamus and pituitary.[17]
  • One report included 156 children and adolescents with medulloblastoma who were treated with surgery, risk-adapted photon craniospinal irradiation, and dose-intensive chemotherapy in the SJMB03 study. The 5-year cumulative incidence of adrenal insufficiency was 13.0%.[54] Adrenal insufficiency was associated with increased hypothalamus dose (HR, 1.112; P < .0001).
  • Although uncommon, ACTH deficiency can occur in patients treated with intracranial radiation doses of less than 24 Gy and in patients with non-CNS tumors or hematological malignancies distant from the hypothalamic-pituitary region. The use of glucocorticoid therapy in treatment protocols may also be associated with steroid-induced adrenal insufficiency, which in some cases may be prolonged.[94,95,96]
  • In a PENTEC report on ACTH deficiency (6 cohorts, 230 patients), the dose associated with a 50% risk was 61 Gy (95% CI, 44.7–119.4).[20] The risk of ACTH deficiency was 20% in children who received a mean dose of 34 Gy in 2-Gy fractions to the hypothalamus-pituitary axis.

Diagnosis and management

  • The diagnosis of ACTH deficiency should be suspected when low plasma levels of morning cortisol are measured (a screening cortisol level collected at 8 AM that is 10 µg/dL or more is reassuring for ACTH sufficiency, whereas a value of 5 µg/dL or lower is suspicious for insufficiency).
  • Confirmation is necessary using dynamic testing such as the low-dose ACTH stimulation test.[92]
  • Because of the substantial risk of central adrenal insufficiency among survivors treated with cranial radiation doses exceeding 30 Gy to the hypothalamic-pituitary axis, endocrine monitoring with periodic dynamic testing as clinically indicated is recommended for this high-risk group.[42]
  • Patients with partial ACTH deficiency may have only subtle symptoms unless they become ill.[42]
  • Illness can disrupt these patients' usual homeostasis and cause a more severe, prolonged, or complicated course than expected. As in complete ACTH deficiency, incomplete or unrecognized ACTH deficiency can be life-threatening during concurrent illness.
  • The treatment of ACTH deficiency relies on replacement with hydrocortisone, including stress dosing in situations of illness to adjust to the body's physiologically increased need for glucocorticoids.[42]

Hyperprolactinemia

  • Hyperprolactinemia has been described in patients who received radiation therapy to the hypothalamus in doses higher than 50 Gy or who underwent surgery that disrupted the integrity of the pituitary stalk.[97]
  • Primary hypothyroidism may lead to hyperprolactinemia as a result of hyperplasia of thyrotrophs and lactotrophs, presumably caused by TRH hypersecretion.
  • The prolactin response to TRH is usually exaggerated in these patients.[50,98]
  • Hyperprolactinemia may result in delayed puberty, galactorrhea, menstrual irregularities, loss of libido, hot flashes, infertility, and osteopenia. Hyperprolactinemia resulting from cranial radiation therapy is rarely symptomatic and is frequently associated with hypogonadism (both central and primary).
  • Hyperprolactinemia rarely requires treatment.[99]

Table 11 summarizes pituitary gland late effects and the related health screenings.

Table 11. Pituitary Gland Late Effectsa
Predisposing Therapy Endocrine/Metabolic Effects Health Screening
BMI = body mass index; FSH = follicle-stimulating hormone; LH = luteinizing hormone; T4 = thyroxine; TSH = thyroid-stimulating hormone.
a Adapted from theChildren's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers.
b Testicular volume measurements are not reliable in the assessment of pubertal development in boys exposed to chemotherapy or direct radiation to the testes.
c Appropriate only at diagnosis. TSH levels are not useful for follow-up during replacement therapy.
Tumor or surgery affecting hypothalamus/pituitary. Radiation exposing hypothalamic-pituitary axis. Growth hormone deficiency Assessment of nutritional status
Height, weight, BMI, Tanner stageb
Tumor or surgery affecting hypothalamus/pituitary or optic pathways; hydrocephalus. Radiation exposing hypothalamic-pituitary axis. Precocious puberty Height, weight, BMI, Tanner stageb
FSH, LH, estradiol, or testosterone levels
Tumor or surgery affecting hypothalamus/pituitary. Radiation exposing hypothalamic-pituitary axis. Gonadotropin deficiency History: puberty, sexual function
Examination: Tanner stageb
FSH, LH, estradiol or testosterone levels
Tumor or surgery affecting hypothalamus/pituitary. Radiation exposing hypothalamic-pituitary axis. Central adrenal insufficiency History: failure to thrive, anorexia, episodic dehydration, hypoglycemia, lethargy, unexplained hypotension
Endocrine consultation for those with radiation dose ≥30 Gy
Radiation exposing hypothalamic-pituitary axis. Hyperprolactinemia History/examination: galactorrhea
Prolactin level
Radiation exposing hypothalamic-pituitary axis. Overweight/obesity Height, weight, BMI
Blood pressure test
Components of metabolic syndrome (abdominal obesity, hypertension, dyslipidemia, impaired glucose metabolism) Fasting blood glucose level and lipid profile
Tumor or surgery affecting hypothalamus/pituitary. Radiation exposing hypothalamic-pituitary axis. Central hypothyroidism TSHc free thyroxine (free T4) level

Testis and Ovary

Testicular and ovarian hormonal functions are discussed in the Late Effects of the Reproductive System section of this summary.

Metabolic Syndrome

An increased risk of metabolic syndrome or its components has been observed among survivors of childhood cancer. The evidence for this outcome ranges from clinically manifested conditions that are self-reported by survivors to retrospectively assessed data in medical records and hospital registries to systematic clinical evaluations of clinically well-characterized cohorts. Studies have been limited by cohort selection and participation bias, heterogeneity in treatment approach, time since treatment, and method of ascertainment. Despite these limitations, compelling evidence indicates that metabolic syndrome is highly associated with cardiovascular events and mortality.

Definitions of metabolic syndrome are evolving but generally include a combination of central (abdominal) obesity with at least two of the following features:[100]

  • Hypertension.
  • Atherogenic dyslipidemia (elevated triglycerides, reduced high-density lipoprotein [HDL] cholesterol).
  • Abnormal glucose metabolism (fasting hyperglycemia, hyperinsulinism, insulin resistance, diabetes mellitus type 2).

Evidence (prevalence of and risk factors for metabolic syndrome in childhood cancer survivors):

  1. French investigators evaluated the overall and age-specific prevalence of and risk factors for metabolic syndrome and its components among 650 adult survivors of childhood leukemia treated without HSCT.[101]
    • The overall prevalence of the condition was 6.9%, with the following age-specific cumulative prevalence:
      • 20 years—1.3%.
      • 25 years—6.1%.
      • 30 years—10.8%.
      • 35 years—22.4%.
    • The prevalence of individual components of the metabolic syndrome was as follows:
      • Increased fasting glucose—5.8%.
      • Increased triglycerides—11.7%.
      • Increased abdominal circumference—16.7%.
      • Decreased HDL cholesterol—26.8%.
      • Increased blood pressure—36.7%.
    • Clinical factors significantly predicting the risk of metabolic syndrome included male sex (OR, 2.64; 95% CI, 1.32–5.29), age at last evaluation (OR, 1.10; 95% CI, 1.04–1.17) and body mass index (BMI) at diagnosis (OR, 1.15; 95% CI, 1.01–1.32), but not cumulative steroid dose. Irradiated and nonirradiated patients exhibited different patterns of metabolic abnormalities, with more frequent abdominal obesity in irradiated patients and more frequent hypertension in nonirradiated patients.
  2. A study monitored 784 long-term childhood ALL survivors (median age, 31.7 years) for a median follow-up of 26.1 years.[102]
    • The prevalence of metabolic syndrome was 33.6%, which was significantly higher than that in a cohort of age-, sex-, and race-matched controls (n = 777) from the National Health and Nutrition Examination Survey (RR, 1.43; 95% CI, 1.22–1.69).
    • Risk factors associated with metabolic syndrome in this study included older age and past exposures to cranial radiation therapy.
    • Components of the metabolic syndrome that were significantly more prevalent in ALL survivors than in controls included obesity, insulin resistance, hypertension, and decreased HDL levels.
  3. The French childhood leukemia survivors' cohort showed that the prevalence of metabolic syndrome was increased among childhood leukemia survivors (n = 1,025), relative to controls (n = 3,202).[103]
    • Metabolic syndrome was found in 10.3% of patients (mean follow-up, 16.3 years) and 4.5% of controls (OR, 2.49; P < .001). Transplant patients treated with TBI had the highest risk (OR, 6.26; P < .001). Other treatment groups that also showed a higher risk than controls included patients treated with chemotherapy only. ORs were 1.68 (P = .005) after chemotherapy only, 2.32 (P = .002) after chemotherapy and cranial irradiation, and 2.18 (P = .057) after transplant without irradiation.
    • Compared with controls, unique profiles were seen in survivors according to treatment. Patients who received TBI and developed metabolic syndrome had a smaller waist circumference than controls. In contrast, patients who were treated with cranial irradiation and developed metabolic syndrome had a larger waist circumference than controls. Additionally, TBI recipients had increased triglyceride levels, fasting glucose levels, and systolic blood pressure.
  4. In a prospective study of 164 long-term survivors of embryonal tumors treated with abdominal radiation therapy (median follow-up, 26 years), nephroblastoma (OR, 5.2) and neuroblastoma (OR, 6.5) survivors had more components of metabolic syndrome than did controls.[104]
    • Compared with survivors who did not receive radiation therapy, survivors treated with abdominal irradiation had higher blood pressure, triglycerides, low-density lipoprotein cholesterol, and total fat percentage, which were assessed by dual-energy x-ray absorptiometry.

Lifestyle impact on modifiable risk factors

  • Modifiable risk factors (such as diet, physical activity, and smoking habits) may impact the risk of developing metabolic syndrome in childhood cancer survivors.
  • Several studies have provided support for the potential benefits of lifestyle modifications in reducing cardiovascular disease risk.[105,106,107]

Evidence (lifestyle modifications to reduce cardiovascular risk in childhood cancer survivors):

  1. Survivors participating in the SJLIFE study who were adherent to a heart-healthy lifestyle had a lower risk of metabolic syndrome.[105]
    • Females (RR, 2.4; 95% CI, 1.7–3.3) and males (RR, 2.2; 95% CI, 1.6–3.0) in the cohort who did not follow recommended dietary and physical activity guidelines had a more than twofold excess risk of having clinical features of the metabolic syndrome.
  2. A CCSS investigation evaluated the impact of exercise on cardiovascular disease risk among survivors of Hodgkin lymphoma.[106]
    • Vigorous exercise was associated with a lower risk of cardiovascular events in a dose-dependent manner, independent of cardiovascular risk profile and treatment.
    • Survivors who were adherent to national vigorous-intensity exercise guidelines had a 51% reduction in the risk of any cardiovascular event compared with those not meeting the guidelines.
  3. Another CCSS investigation evaluated the association of exercise with mortality in adult survivors of childhood cancer.[107]
    • After adjusting for chronic health conditions and treatment exposures, all-cause mortality was inversely associated with survivor-reported exercise quartiles (0, 3–6, 9–12, and 15–21 metabolic equivalent task [MET] hours/week).
    • Survivors who endorsed recommended levels of vigorous exercise (≥9 MET hours/week) in early adulthood and those who increased exercise over 8 years had a lower risk of mortality.

Abnormal glucose metabolism

For individuals treated at a young age (age <11 years), abdominal radiation therapy and TBI are increasingly recognized as independent risk factors for diabetes mellitus in childhood cancer survivors.[2,108,109,110,111,112]

Evidence (risk factors for diabetes mellitus in childhood cancer survivors):

  1. A single-center cohort study of 532 long-term adult survivors (median follow-up, 17.9 years; median age, 25.6 years) observed the following:[109]
    • Treatment, but not genetic variation, was strongly associated with the occurrence of the components of metabolic syndrome.
    • Metabolic syndrome was more frequent in survivors who received cranial (23.3%, P = .002) or abdominal (23.4%, P = .009) radiation therapy than in survivors who did not receive radiation therapy (10.0%).
  2. A cross-sectional study evaluated cardiovascular risk factors and insulin resistance in a clinically heterogeneous cohort of 319 childhood cancer survivors 5 or more years since diagnosis and 208 sibling controls.[113]
    • Insulin resistance was significantly higher in survivors treated with cisplatin plus cranial irradiation (92% brain tumors) and in those who received steroids but no cisplatin (most leukemia survivors), compared with siblings.
    • Insulin resistance did not differ between survivors treated with surgery alone and siblings.
    • Among survivors, analysis of individual chemotherapy agents failed to find associations with cardiovascular risk factors or insulin resistance.
    • Compared with siblings, nearly all chemotherapeutic agents, when examined individually, seemed to be associated with a high cardiovascular risk profile, characterized by lower total lean body mass, higher percentage fat mass, and insulin resistance.
  3. In a European multicenter cohort of 2,520 childhood cancer survivors (median follow-up, 28 years), significant associations were found between diabetes mellitus and increasing doses of radiation therapy to the tail of the pancreas. This finding supports the contribution of radiation-induced islet cell injury to impairments of glucose homeostasis in this population.[110]
  4. A report from the CCSS compared 8,599 childhood cancer survivors with 2,936 randomly selected sibling controls, and adjusted for age, BMI, and several demographic factors.[114]
    • The risk of diabetes mellitus was 1.8 times higher in survivors (95% CI, 1.3–2.5; P < .001).
    • Significant associations were found between diabetes mellitus and young age at diagnosis (0–4 years), the use of alkylating agents, and abdominal radiation therapy or TBI.
    • Survivors exposed to abdominal radiation had a 3.4-fold higher increased risk of diabetes (95% CI, 2.3–5.0; P < .001) when compared with siblings and after adjusting for BMI. Compared with siblings, survivors of neuroblastoma and Wilms tumor who were treated with abdominal radiation therapy had a 6.9-fold and 2.1-fold increased risk of diabetes, respectively. Individuals in these groups who had not been exposed to abdominal radiation therapy were not at increased risk.
    • Survivors were significantly more likely to be receiving medication for hypertension, dyslipidemia, and/or diabetes mellitus than were sibling controls.

Table 12 summarizes metabolic syndrome late effects and the related health screenings.

Table 12. Metabolic Syndrome Late Effectsa
Predisposing Therapy Potential Late Effects Health Screening
BMI = body mass index.
a Adapted from theChildren's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers.
Abdominal irradiation; total-body irradiation. Components of metabolic syndrome (abdominal obesity, hypertension, dyslipidemia, impaired glucose metabolism) Height, weight, BMI, blood pressure test
Laboratory tests: Fasting glucose and lipids

Body Composition: Underweight, Overweight, and Obesity

  • Childhood cancer survivors are at risk of experiencing abnormal body composition, which includes becoming underweight (BMI, <18.5), becoming overweight (BMI, >25.0 to BMI, <30.0), or being affected by obesity (BMI, ≥30.0).
  • BMI at diagnosis has been identified as a significant predictor of being underweight or overweight at follow-up. This finding suggests that genetic or environmental factors contribute to the development or persistence of abnormal body composition.[115,116]

Underweight

  • CCSS investigators identified treatment-related risk factors for being underweight, including TBI (females) or abdominal irradiation (males), use of alkylating agents, and use of anthracyclines.[116]
  • Among a cohort of 893 Dutch childhood cancer survivors monitored for a median of almost 15 years, being underweight was linked to a high prevalence of moderate to extreme adverse health statuses and reports of a major medical condition.[115]

Overweight/obesity

  • To date, patients with cancer who have an increased incidence of being affected by overweight and obesity are primarily ALL [115,117,118,119,120,121] and CNS tumor [40,97] survivors who were treated with cranial radiation therapy.[116,122]
  • The development of overweight/obesity after cranial radiation therapy is multifactorial and includes the following:[119,123,124]
    • Growth hormone deficiency.
    • Leptin sensitivity.
    • Reduced levels of physical activity and energy expenditure.

Evidence (risk factors for overweight/obesity):

  1. In the nationwide Dutch Childhood Cancer Survivor Study (DCCSS-LATER) cohort of adult survivors of childhood cancer (n = 2,338), investigators found that having excess body weight (BMI >2.5 kg/m2) occurred in almost one-half of all long-term survivors. This incidence was not increased compared with the general population.[125]
    • Overweight incidence was higher in women aged 50 years and older, and morbid obesity incidence was higher in men aged 50 years and older.
    • Factors such as having excess body weight at cancer diagnosis, receiving cranial irradiation, and having growth hormone deficiency were all associated with long-term overweight status. Corticosteroids were not associated with overweight status.
    • Dual-energy x-ray absorptiometry–based classification identified overweight in an additional 30% of survivors, particularly those treated with abdominal irradiation, TBI, anthracyclines, and platinum chemotherapy.
  2. CCSS investigators reported the following independent risk factors for obesity in childhood cancer survivors including treatment, lifestyle, and medication use:[126]
    • Cancer diagnosed at ages 5 to 9 years (RR, 1.12; 95% CI, 1.01–1.24).
    • Abnormal physical functioning (RR, 1.19; 95% CI, 1.06–1.33).
    • Hypothalamic-pituitary radiation dose of 20 Gy to 30 Gy (RR, 1.17; 95% CI, 1.05–1.3; P = .01).
    • Specific antidepressant use of paroxetine (RR, 1.29; 95% CI, 1.08–1.54).
    • Survivors who adhered to the U.S. Centers for Disease Control and Prevention guidelines for vigorous physical activity (RR, 0.90; 95% CI, 0.82–0.97; P = .01) and who had a medium amount of anxiety (RR, 0.86; 95% CI, 0.75–0.99; P = .04) had a lower risk of obesity.[126]

Body composition alterations after childhood ALL

Evidence (risk factors for body composition alterations):

  1. Moderate-dose cranial radiation therapy (18–24 Gy) among ALL survivors is associated with obesity, particularly in females treated at a young age.[117,119,127]
    • Female adult survivors of childhood ALL who were treated with cranial radiation therapy of 24 Gy before age 5 years are four times more likely to be affected by obesity than are women who have not been treated for a cancer.[117]
    • Women treated with 18 Gy to 24 Gy cranial radiation therapy before age 10 years have a substantially greater rate of increase in their BMI through their young adult years than do women who were treated for ALL with only chemotherapy or women in the general population.[119]
    • These women also have a significantly increased visceral adiposity and associated insulin resistance.[128,129]
  2. Body composition alterations appear to be attenuated in males.
    • A study of long-term male survivors of ALL (mean age, 29 years) observed significantly higher body adiposity than in age-matched controls, despite normal weight and BMI.[130]
    • Potential indicators of increased adiposity included high leptin and low sex hormone–binding globulin levels.[130]
    • Serum testicular endocrine markers (testosterone, FSH, or inhibin B) did not correlate with body adiposity.[130]
  3. ALL therapy regimens are associated with increases in BMI shortly after completion of therapy, and possibly with a higher risk of obesity in the long term.[120,121,131,132,133]
    • Several studies have reported that survivors of childhood ALL treated with chemotherapy alone also exhibit long-term changes in body composition, with relative increases in body fat [129,134,135,