Prophylactic mastectomy may reduce your risk of breast cancer. Learn how doctors assess breast cancer risk and how prophylactic mastectomy may help prevent breast cancer. By Mayo Clinic Staff

Finding out you're at high risk of breast cancer leads to difficult questions and decisions. One such question is whether to have prophylactic mastectomy — surgery to remove one or both breasts in hopes of preventing or reducing your risk of breast cancer.

Keep in mind that being identified as high risk doesn't mean you'll get cancer. All it means is that your likelihood of developing breast cancer is several times higher than that of an average-risk woman. Understanding your individual level of risk can help you weigh your options for risk-reducing strategies, including prophylactic mastectomy.

All women are at risk of breast cancer just by being female and advancing in age. But some factors increase your risk significantly. You may consider prophylactic mastectomy if you have:

  • Already had cancer in one breast. If you develop breast cancer and have a strong family history of the disease, you may decide to have both breasts removed. One breast is removed to get rid of the cancer, and the other, unaffected breast is removed to greatly reduce the possibility of developing another breast cancer in the future.
  • A family history of breast cancer. If you have a mother, sister or daughter with breast cancer, especially if she was diagnosed before age 50, you may be at an increased risk of developing breast cancer. If you have multiple family members with breast cancer or ovarian cancer, your risk of breast cancer may be greater. A predisposition to breast cancer can be passed on to you through your mother's or father's side of the family.
  • Positive results from gene testing. Genetic testing can identify if you have mutations in genes that increase your risk of breast cancer or other cancers such as ovarian cancer. Genes known to increase the risk of breast and ovarian cancers include BRCA1 and BRCA2. If you have a strong family history of breast cancer, you may consider meeting with a genetic counselor to discuss genetic testing.
  • Breast changes that increase your risk of breast cancer. Your doctor may have discovered abnormal cells in the milk-producing glands (lobules) of your breast (lobular carcinoma in situ). This finding is not cancer, but is a marker of an increased risk of developing breast cancer in both breasts.
  • Radiation therapy. If you had radiation therapy to your chest before age 30, you have an increased risk of developing breast cancer.
  • Dense breasts. Dense breast tissue is associated with breast cancer, and it makes it harder for doctors to diagnose breast cancer. In certain cases, a woman with dense breasts may consider a prophylactic mastectomy, especially if she has other risk factors, such as a strong family history of breast cancer or precancerous conditions.

Your doctor determines whether you're at high risk of breast cancer based on your risk factors and on mathematical models that calculate your lifetime risk of breast cancer.

Deciding what to do with the knowledge that you are at high risk of breast cancer is a complex and time-consuming process. It's best if you can work with a team of health professionals to get a complete evaluation of your risk and all of your options. Many breast centers are staffed with breast-health specialists, genetic counselors, breast surgeons and reconstructive surgeons who can collaborate with you. Second opinions are strongly recommended for women considering prophylactic mastectomy.

Making the decision whether to have prophylactic mastectomy is not urgent. Give yourself time to weigh all the pros and cons. You may want to discuss your concerns and feelings with a breast-health specialist and psychologist.

Prophylactic mastectomy reduces the risk of developing breast cancer by 90 percent in high-risk women. That means, for every 100 women with a high risk of breast cancer that undergo prophylactic mastectomy, 90 of those women will never be diagnosed with breast cancer. Ten women can be expected to develop breast cancer after the surgery.

Having a prophylactic mastectomy doesn't guarantee that you'll never develop breast cancer because all of your breast tissue can't be removed during surgery. Sometimes breast tissue can be found in your armpit, above your collarbone or on the upper part of your abdominal wall, where it may not be detected at the time of your surgery. Breast tissue remaining in your body can still develop breast cancer, although the chances are slim.

As is true with any surgery, prophylactic mastectomy comes with potential complications, including:

  • Bleeding
  • Infection
  • Pain
  • Development of scar tissue
  • Anxiety or disappointment about changes to your appearance

If you're at high risk of breast cancer and you decide against prophylactic mastectomy, you do have other options for early detection and risk reduction:

  • Breast cancer screening. The goal of surveillance is to detect cancer at its earliest stage. Screening recommendations vary, and your doctor may suggest a screening schedule based on your individual situation. The American Cancer Society recommends that women at high risk get a mammogram and magnetic resonance imaging (MRI) every year beginning at age 30. Screening may also involve a clinical breast exam by your doctor and breast self-exams you can do on your own.
  • Medications to reduce risk. In this approach, you may reduce your risk of breast cancer by taking drugs that block the effects of estrogen, because estrogen can promote breast cancer development and growth. Medications used for this purpose include tamoxifen, raloxifene (Evista) and, in certain cases, exemestane (Aromasin). These drugs may reduce the risk of invasive breast cancer by approximately 50 percent. However, they carry a risk of side effects. Talk with your doctor about the risks and benefits of these medications.
  • Surgery to remove the ovaries. Prophylactic oophorectomy can reduce the risk of both breast cancer and ovarian cancer. Women with BRCA mutations also have an increased risk of ovarian cancer. Prophylactic oophorectomy may reduce the risk of breast cancer up to 50 percent in women with a high risk of breast cancer.
  • Healthy lifestyle changes. Healthy lifestyle changes, such as maintaining a healthy weight, exercising most days of the week, limiting alcohol use and avoiding hormone therapy during menopause, may reduce the risk of breast cancer. But it's not clear how much these changes can reduce the risk for women with an already high risk of breast cancer. Discuss these healthy lifestyle changes with your doctor to better understand how they might impact your breast cancer risk when combined with other risk-reduction strategies.
Dec. 22, 2011