Breast cancer is a disease in which cancer cells grow in the breast tissue. It is the most common cancer in women in the United States. The breast is made up of lobules, which make milk and duct that allow milk to pass to the nipple. The lobules are surrounded by fat, connective tissue, blood vessels, and lymphatic tissue.

There are many different types of types of breast cancer, some examples include:

  • Ductal carcinoma situ—A cancer that starts in the ducts, and is only found in the ducts.
  • Invasive ductal carcinoma—A cancer that starts in the ducts of the breast and spreads into surrounding tissues. This is the most common type of breast cancer in women.
  • Invasive lobular carcinoma—A cancer that starts in the lobules of the breast and spreads into surrounding tissues.
  • Inflammatory carcinoma—A rare and aggressive form of breast cancer that can be difficult to treat. This cancer invades the lymphatic vessels of the skin and can be very extensive. It is very likely to spread to other parts of the body.
  • Paget's disease—A very rare cancer of the areola and nipple. Although Paget's does not arise from glandular tissue in the breast, it can be associated with both in situ and infiltrating breast cancers.

Breast Cancer

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Cancer occurs when cells in the body divide without control or order. Eventually these uncontrolled cells form a growth or tumor. The term cancer refers to malignant growths that are able to invade other tissue. The cancer will continue to grow and spread in the area. Once the cancer has invaded lymph nodes or blood vessels some cancer cells can metastasize, travel to other areas of the body and form new tumors. The lymph nodes associated with breast cancer are in the armpit, above the collarbone, and in the chest.

It is not clear exactly what causes these problems in the cells.

Risk Factors

Factors that may increase your chance of breast cancer include:

  • Age—breast cancer is more common in women aged 50 years and older
  • Genetic mutations, such as BRCA1, BRCA2, and others
  • Rare genetic conditions such as Li-Fraumeni syndrome
  • Radiation therapy before the age of 30 years old
  • Personal history of breast cancer
    • Example: Women with Lobular carcinoma in situ (LCIS) appear to have a 7-10 times greater risk of developing some form of breast cancer over the next 20 years.
  • Family members with breast cancer such as:
    • Mother, sister, or daughter with breast cancer
    • Multiple members on one side of family
    • Father, brother, or son with breast cancer
  • Changes in breast tissue, such as atypical ductal hyperplasia, and radial scar formation
  • Excess body weight or obesity, particularly after menopause
  • Increased exposure to estrogen over a lifetime which can occur with:
    • Early onset of menstruation, before 12
    • Late onset of menopause
    • No childbearing or late childbearing
    • Start of menopause after 55
    • Combined estrogen and progestin hormone therapy—when taken for more than 5 years
    • Certain oral contraceptives
  • Increased breast density—more connective tissue and less fatty tissue
  • Tobacco use
  • Drinking alcohol—risk for breast cancer increases as the amount of alcohol consumed increases
  • Women who have taken diethylstilbestrol (DES), and women who were born to women that took DES.

Note: Most women with known risk factors do not get breast cancer. Many women who get breast cancer have none of the risk factors listed above except age.


Some may have no symptoms at all while other may have:

  • One or more lumps in the breast which may or may not be painful
  • One or more lumps in lymph nodes near the breast, under your arm, or collarbone which may or may not be painful
  • Thickening or swelling in or around the breast
  • A change in the size or shape of the breast
  • Nipple discharge or tenderness
  • Inward sinking of nipple
  • Ridges or pitting of the breast skin, like the skin of an orange
  • A change in the way the skin of the breast or nipple looks or feels (for example, red, flaky, sores, or dimpling in skin)
  • Pain in the breast

Note: These symptoms may also be caused by other, less serious health conditions. See a doctor about any symptoms that may be worrisome.


Breast cancer may be found during a mammogram screening. Screening recommendations for women include:

  • Women age 40-49—discuss with doctor whether mammograms are needed
  • Women age 50-74—mammogram every 1-2 years
  • Age 50-74—mammogram every 1-2 years
  • Mammograms every year for women at high risk. Age at start will depend on the reason for high risk. May begin as early as 20 years of age.

Breast changes may also be found during a regular medical visit. The doctor will ask about your symptoms and medical history. A physical exam, breast exam, and blood tests will be done.

If breast cancer is suspected from screening or physical exam, imaging tests may be needed to confirm diagnose and evaluate the cancer. Imaging tests may include:

Your doctor will test the suspicious breast tissue and nearby lymph nodes. A sample of the tissue will be removed and sent to a lab to look for cancer cells. This can be done with different types of biopsies, such as:

  • Fine-needle aspiration—Removal of fluid and/or cells from a breast lump using a thin needle.
  • Needle biopsy —Removal of tissue with a needle from an area that looks unusual on a mammogram, but cannot be felt.
  • Surgical biopsy—removal of suspicious tissue

If cancer is present, your doctor may order tests to learn about the type of cancer. These may include:

  • Blood tests—To look for tumor markers or genetic mutations.
  • Tissue evaluation—to find certain cancer characteristics that help to decide the best treatment options. Some relevant factors include:
    • Oncotype DX—a group of genes known to effect how the cancer will behave and react to treatment. Knowing which genes are present will help predict cancer growth and treatment response.
    • Presence of estrogen and progesterone receptors—proteins on the cell that pick up hormones which stimulate cancer growth.
    • Presence of HER2/neu—genes related to rapid cancer development and growth.

A combination of your test results will help to determine the stage of cancer you have. Staging is used to guide your treatment plan. Like other cancers, breast cancer is staged from 0-IV (0-4):

  • Stage 0 (carcinoma in situ)—abnormal, noninvasive cells are only found in a specific area, such as nipple, or ducts.
  • Stage I-III (1-3)—cancer is beginning to invade nearby tissue. Higher stages mean more tissue is affected.
  • Stage IV (4)—cancer that has spread to other parts of the body such as lungs, bone, liver, or brain. Cancer that has spread is called metastatic cancer.


Cancer treatment varies depending on a number of factors including the stage and type of cancer. The plan may include one or more types of treatment to attack any current cancer and reduce the risk of spread or recurrence.

Treatment options include:

The goal of surgery is to remove as much of the cancer as possible. The surgery may also be used to remove tissue for detailed testing. The type of surgery will depend on the stage and type of cancer and overall treatment plan. Options include:

  • Lumpectomy —Removal of the breast cancer and some normal tissue around it. Some of the lymph nodes under the arm may also be removed.
  • Segmentectomy—Removal of the cancer and a larger area of normal breast tissue around it.
  • Simple mastectomy—Removal of the breast, or as much of the breast as possible. This is the most common surgery for breast cancer treatment.
  • Skin-sparing mastectomy—The same amount of tissue is removed as with a simple mastectomy, but the skin over the breast is spared. This can be used when immediate breast reconstruction surgery is planned. One type of this procedure can also spare the nipple and areola. This may not be an option for all women.
  • Modified radical mastectomy—Removal of the whole breast, the lymph nodes under the arm and, often, the lining over the chest muscles.
  • Radical mastectomy—Removal of the breast, both chest muscles, the lymph nodes under the arm, and some additional fat and skin. This procedure is only considered in rare cases, for cancer that has spread to the chest muscles.
  • Sentinel lymph node biopsy—the sentinel node is the first area of lymph nodes that the cancer will drain into. Once found, these nodes will be removed and tested. Additional lymph nodes will be removed if the cancer has spread beyond the sentinel nodes.
  • Axillary lymph node dissection—Removal of the lymph nodes under the arm. This is done to help determine whether cancer cells have entered the lymphatic system.

Radiation therapy may be used to kill cancer cells or stop their growth. It is often used after surgery to try to eliminate any remaining cancer cells and decrease chance of recurrence. Radiation therapy may also be used to shrink tumors that are causing symptoms. The main types of radiation include:

  • External radiation therapy—Radiation directed at the breast from a source outside the body.
  • Internal radiation therapy—Radioactive materials are placed into the breast in or near the cancer cells.
  • Microwave thermotherapy—Used to bring cancer cells to a high temperature. This may make them more sensitive to traditional radiation therapy treatment. It is early in the research process and may not be available in all areas.

Chemotherapy is the use of drugs to kill cancer cells. It may be given in many forms including pill, injection, or IV. The drugs enter the bloodstream and travel through the body killing mostly cancer cells. Some healthy cells are killed as well causing a variety of symptoms.

The following therapies may be to used as overall part of care:

  • Biologic therapy—use of enhanced natural processes to attack cancer or its support systems. There are a number of biologic therapies including:
    • Immunotherapy or biologic response modifier (BRM) therapy—stimulate or redirect the immune system to attack or slow cancer cells.
    • Targeted therapy—attacks specific characteristics of cancer cells that allow cancer to grow. Attacking the support systems of cancer can slow or stop its growth.
  • Hormone blocking therapy —medication that stops production of specific hormones in the body. This is only effective therapy for those with hormone-dependent (sensitive) tumors. Blocking the related hormones can slow or stop the growth of tumors.

Cancer treatments can cause some side effects like nausea, anemia, pain, or bone loss. Other medications or treatments may be needed to minimize these problems throughout your cancer treatment.


Not all cancers can be prevented but the risk of some cancers may be reduced with:

  • Regular physical activity
  • Reaching and maintaining a healthy weight with diet rich in fruits and vegetables
  • Avoid or limit alcohol

Options that may be available for those with a high risk of breast cancer include:

  • Medications to prevent breast cancer in high-risk, postmenopausal women. These medications increase your chances of having blood clots and stroke. Talk to your doctor about whether medication is right for you.
  • Surgery, called prophylactic mastectomy, to remove breasts before cancer develops.