Can breast cancer be prevented?

There is no sure way to prevent breast cancer. But there are things all women can do that might reduce their risk and help increase the odds that if cancer does occur, it is found at an early, more treatable stage.

Lowering your risk: You can lower your risk of breast cancer by changing those risk factors that are under your control. Body weight, physical activity, and diet have all been linked to breast cancer, so these might be areas where you can take action.

At this time, the best advice about diet and activity to possibly reduce the risk of breast cancer is to:

• Get regular physical activity.
• Reduce your lifetime weight gain by eating fewer calories and getting regular exercise.
• Avoid or limit your alcohol intake.

To find out more, see our document, American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention.

Women who choose to breastfeed for at least several months may also reduce their breast cancer risk. Not using hormone therapy after menopause can also help you avoid raising your risk.

It's not clear at this time whether chemicals that have estrogen-like properties (like those found in some plastic bottles or certain cosmetics and personal care products) increase breast cancer risk. If there is an increased risk, it is likely to be very small. Still, women who are concerned may choose to avoid products that contain these substances when they can.

Finding breast cancer early: It is also important for women to follow the American Cancer Society’s guidelines for finding breast cancer early. (See the section, “How is breast cancer found?”)

For women who are or may be at increased risk

If you have a higher risk for breast cancer there may be some things you can do to reduce your chances of getting breast cancer. Before deciding which, if any, of these may be right for you, talk with your doctor.

Genetic testing

There are tests that can tell if a woman has certain changed (mutated) genes linked to breast cancer. With this information, women can then take steps to reduce their risk. Recently the US Preventive Services Task Force made recommendations for genetic testing. They suggest that only women with a strong family history be evaluated for genetic testing for BRCA mutations. This group is only about 2% of adult women in the United States. While many women may have relatives with breast cancer, in most cases this is not the result of BRCA gene mutations.

If you are thinking about genetic testing, you should talk to a genetic counselor, nurse, or doctor qualified to explain the process and what the results of these tests could mean. It is very important that you know what genetic testing can and can’t tell you, and to carefully weigh the pros and cons of testing before these tests are done. Testing costs a lot and may not be covered by some health insurance plans. For more information, see our document, Genetic Testing: What You Need to Know. You might also want to visit the National Cancer Institute web site: www.cancer.gov/cancertopics/factsheet/Risk/BRCA.

Breast cancer chemoprevention

Chemoprevention is the use of drugs to reduce the risk of cancer. The drugs tamoxifen and raloxifene (Evista^®) have both been shown to lower breast cancer risk in studies, and are approved for this use by the FDA. Raloxifene is only approved for use in women after menopause, while tamoxifen can be taken by both pre-menopausal and post-menopausal women. Other drugs (such as aromatase inhibitors) are also being studied. To learn more about these drugs, please see the American Cancer Society document, Medicines to Reduce Breast Cancer Risk.

Preventive surgery for women with very high breast cancer risk

For the few women who are at a very high risk for breast cancer, surgery to remove the breasts or ovaries may be an option.

Preventive (prophylactic) mastectomy: For some women who are at very high risk for breast cancer, this surgery (a double mastectomy) may be an option. In this operation both breasts are removed before there is any known breast cancer. While this operation removes nearly all of the breast tissue, a small amount remains. This operation greatly reduces the risk of breast cancer, but the disease can still start in the breast tissue that is left.

The reasons for having this type of surgery need to be very strong. There is no way to know ahead of time whether this surgery will help any one woman. The American Cancer Society Board of Directors has stated that “only very strong clinical and/or pathologic indications warrant doing this type of preventive operation.” A second opinion is strongly recommended before making a decision to have this type of surgery.

Some women with breast cancer in one breast choose to have that breast removed to treat the cancer, but they also have the other breast removed to prevent a second breast cancer. This is more common in women who have BRCA mutations, as their risk of a second breast cancer is very high.

Preventive ovary removal (prophylactic oophorectomy): Women with a certain gene change (BRCA mutation) who have their ovaries removed before menopause may reduce their risk of breast cancer by half or more. This is because taking out the ovaries removes the main sources of estrogen in the body.

Although this document is not about ovarian cancer, it is important that women with this gene change also know that they also have a high risk of getting ovarian cancer. Most doctors recommend that these women have their ovaries removed after they are done having children.