What is breast cancer?

Cancer develops in the breast tissue when cells grow out of control. The cells can form a malignant tumor (visible on X-rays or felt as a lump) that invades surrounding tissues or spreads (metastasizes) to other parts of the body. Usually, breast cancers begin in ducts in the breast and in the lobules, the glands that make breast milk. Other types of breast cancer called sarcomas start in the cells of the muscle, fat or connective tissue. The cancer can also spread into the blood and lymph vessels that carry it to other parts of the body.

According to the American Cancer Society (ACS), the most common types of breast cancer are ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC). In situ means that breast cancers have not spread; if the cancer is classified invasive, this suggests that cancerous cells have spread into surrounding breast tissue. Less common types of breast cancer include inflammatory breast cancer, Paget disease of the nipple, Phyllodes tumor and angiosarcoma. The last is rare and is usually seen in people who have had prior radiation treatment to the breast.

Who gets breast cancer?

Breast cancer occurs primarily in women, regardless of race or ethnicity. It is the most common cancer among women in the United States and the most common cause of death from cancer among Hispanic women, the second most common cause of death from cancer among white, Black and Asian/Pacific Islander women and the third most common cause of death from cancer among American Indian/Alaska Native Women, according to the Centers for Disease Control and Prevention (CDC).

But men can also develop breast cancer. According to estimates by the American Cancer Society, about 2,470 new cases of invasive breast cancer will be diagnosed in men in 2017, and almost 460 males will die from the disease.

What are the symptoms of breast cancer?

The most common sign of cancer in the breast is a lump or mass in that area. Most likely, a hard and painless mass with irregular edges is cancer. But sometimes, cancerous masses can be tender, soft or rounded as well as painful. This is why the ACS recommends that individuals visit a health care provider when they notice a new mass, lump or change in their breast. Other symptoms include swelling of all or part of a breast (even if no distinct lump is felt), skin irritation or dimpling, breast or nipple pain, nipple retraction (turning inward), redness, scaliness or thickening of the nipples or breast skin, and a discharge other than breast milk from the nipple.

What are the risk factors for breast cancer?

According to the CDC, besides being a woman and getting older other factors that influence a person’s risk of developing breast cancer are:

  • Genetic mutations
  • Early menstrual period
  • Late or no full-term pregnancy
  • Starting menopause after 55
  • Not being physically active
  • Being overweight or obese after menopause
  • Having dense breasts
  • Race and ethnicity
  • Using combination hormone therapy
  • Taking oral contraceptives
  • Family or personal history of breast cancer
  • Personal history of certain noncancerous breast cancers
  • Previous treatments using radiation therapy
  • History of taking the drug diethylstilbestrol (DES)—prescribed from the 1940s through the early 1970s to pregnant women to lower their chances of miscarriage—or having a mother who took DES while pregnant
  • Drinking alcohol

Research also suggests that smoking, exposure to chemicals that can cause cancer and working night shifts may boost the risk for breast cancer.

What is the testing procedure for breast cancer?

The ACS urges women to get regular screenings for breast cancer as a way to detect and diagnose the disease early. This is why doctors recommend mammograms every year for women 45 and older. Women younger than 45 who have a higher than average risk for breast cancer or those who experience changes in their breast should report to their health care provider immediately.

If a mammogram detects changes in the breasts, an ultrasound is used for further examination. This test can determine whether a lump is a solid mass or cyst filled with fluid. If it’s the latter, it’s most likely not cancer.

Once a woman is diagnosed with breast cancer, doctors order a breast MRI scan to measure the size of the cancer, look for other tumors in the breast and check for tumors in the opposite breast. Experts recommend that women at high risk for breast cancer also undergo a breast MRI each year.

Currently, there are experimental breast imaging tests in early stages of research. These include optical imaging tests (passing light into the breast and measuring the light that returns or passes through the tissue), molecular breast imaging, or MBI (a way to follow up on breast problems), positron emission mammography, or PEM (an exam that uses sugar attached to a radioactive particle to detect cancer cells) and electrical impedance imaging, or EIT (use of an electric current passed through the breast to help classify tumors found on a mammogram).

How is breast cancer treated?

Among the specialists that may help a person with treatment are a breast surgeon, a radiation oncologist and a medical oncologist.

Options for treatment usually depend on the type of breast cancer and the stage of the disease, which ranges from 0 to IV (the lower the number the less the cancer has spread; the higher the number the more advanced the disease). Stages also depend on the size of the tumor, whether the cancer has reached nearby lymph nodes or metastasized and spread to other parts of the body.

Treatment can be broken down into two therapies: local and systemic. Local therapies, such as surgery and radiation therapy, treat the cancer without affecting the rest of the body. Systemic treatments, however, can reach cancer cells anywhere in the body. They include chemotherapy, hormone therapy and targeted therapy (a treatment that uses drugs or other substances to precisely identify and attack cancer cells). Immunotherapy (a type of biological therapy that uses substances to stimulate or suppress the immune system to help the body fight cancer) may also be used.

For more information on breast cancer, visit the American Cancer Society.

Last Revised: July 11, 2017