Breast Cancer Overview


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What is breast cancer?

Breast cancer occurs when abnormal cells grow out of control in one or both breasts.
 These cancer cells can spread (metastasize) to nearby tissues and form a mass, called a tumor. The cells can spread within the breast, to nearby lymph nodes and other tissues, and to other parts of the body.

The most common type of breast cancer starts in the ducts of the breast. It's called ductal carcinoma. The second most common type is lobular carcinoma. It starts in the lobes of the breast. Some breast cancer is a mix of both ductal and lobular carcinoma. When abnormal cells in the ducts or lobes of the breast haven't spread, they are said to be noninvasive, or "in situ" (say "in-SY-too"). These include:

  • Ductal carcinoma in situ (DCIS). This is a precancer that may progress to breast cancer. The abnormal cells are only in the ducts of the breast.
  • Lobular carcinoma in situ (LCIS). Because LCIS cells don't spread, it's not considered to be cancer. But having LCIS increases a person's risk of developing breast cancer later in life.

Breast cancer can occur in people who don't identify as female but have breasts. And it can occur even if they had a breast reduction or a mastectomy. There are also some less common types of invasive breast cancer, such as inflammatory breast cancer and male breast cancer.


What causes it?

Doctors don't know exactly what causes breast cancer. But some things are known to increase the chance that you will get it, such as your age and health history.


What are the symptoms?

The most common symptom is a painless lump or thickening in the breast or underarm. But early breast cancer is often found on a mammogram before a lump can be felt. The size, shape, or appearance of the breast may also change. Or the nipple may turn in, look scaly, or leak fluid.


How is it diagnosed?

Depending on your age and risk factors, the doctor may recommend that you have a mammogram. A mammogram can often find a lump that is too small to feel.

During a regular physical exam, your doctor can check your breasts for lumps or changes. You also may find a lump during a breast self-exam.

If there are concerns, the doctor will check to see if there is cancer by examining a sample of cells (biopsy). The results of the biopsy help your doctor know if you have cancer and what type of cancer it is.

You may have other tests to find out the stage of the cancer. The stage is a way for doctors to describe how far the cancer has spread.


How is breast cancer treated?

Treatment for breast cancer is based on the type and stage of the cancer and other things, such as your overall health. The main treatment is surgery to remove the cancer. Other treatment options may include radiation therapy, chemotherapy, endocrine therapy, or targeted therapy.



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Current as of: May 4, 2022

Author: Healthwise Staff

Medical Review: Sarah Marshall MD - Family Medicine & E. Gregory Thompson MD - Internal Medicine & Kathleen Romito MD - Family Medicine & Elizabeth T. Russo MD - Internal Medicine & Douglas A. Stewart MD - Medical Oncology

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