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No intervention is 100% guaranteed to prevent breast cancer. However, women have several options to reduce the risk of developing breast cancer.
- For women with especially strong family histories of breast cancer (such as those with BRCA1 or BRCA2 genetic mutations), a prophylactic mastectomy (preventive removal of the breasts) may be considered. This appears to reduce the risk of developing breast cancer by at least 95%. These women may also consider a prophylactic oophorectomy (removal of the ovaries), which can reduce the risk of developing breast and ovarian cancers. Learn more about the genetics of breast cancer.
- Women who are at higher than normal risk for developing breast cancer may consider chemoprevention (the use of drugs to reduce breast cancer risk). Two drugs, tamoxifen (Nolvadex) and raloxifene (Evista) are approved to lower breast cancer risk. These drugs are called selective estrogen receptor modulators (SERMs). A SERM is a medication that blocks estrogen receptors in some tissues and not others. Women that have gone through menopause (postmenopausal) and women who have not (premenopausal) may take tamoxifen, while raloxifene is only approved for postmenopausal women. Each drug also has different side effects; talk with your doctor about whether you may benefit from chemoprevention for breast cancer. Read more about drugs to reduce breast cancer risk.
- Other ways to lower your risk of breast cancer include getting regular physical activity, staying at a normal weight, and limiting the amount of alcohol you drink. Learn about more lifestyle changes to prevent cancer.
Several breast cancer risk assessment tools have been developed to help a woman estimate her chance of developing breast cancer. The best studied is the Gail model (www.cancer.gov/bcrisktool). After entering some personal and family information, the tool provides a five-year and lifetime estimate of the risk of developing invasive breast cancer. Because it only asks for information about breast cancer in first-degree family members (mother, sister) and doesn't include their age at diagnosis, the tool works best at estimating risk in women who don't have a strong inherited breast cancer risk.
For most women, regular mammography and clinical breast examinations can help find early signs of breast cancer. In addition, women should become familiar with their own breasts. Checking your own breasts for lumps and changes with breast self-examination may help if performed correctly. Talk with your doctor for more information.
Mammography is the best tool doctors have to screen otherwise healthy women for breast cancer, as it has been shown to lower deaths from breast cancer. Like any medical test, mammography involves risks, such as additional invasive testing and anxiety, if the test falsely shows a potential tumor. Occasionally, mammography may miss a cancer.
Different organizations have looked at the evidence, risks, and benefits surrounding mammography and have come to different conclusions about screening schedules:
- The U.S. Preventive Services Task Force (USPSTF) recommends that women 50 to 74 years old undergo mammography every two years. They recommend that mammography be considered in women aged 40 to 49 after assessing the risks and benefits of this test with a physician.
- The American Cancer Society (ACS) recommends yearly mammography beginning at age 40.
All women should talk with their doctors about mammography and decide on an appropriate screening schedule.
The USPSTF and ACS also differ on their recommendations for clinical breast examinations. The USPSTF recommends a clinical breast examination along with mammography, and the ACS recommends a clinical breast examination every one to three years until age 40, then annually. Breast self-examination has not been shown to lower deaths from breast cancer, but it is important for women to become familiar with their breasts so that they can be aware of any changes.
Other methods of breast imaging, such as ultrasound and magnetic resonance imaging (MRI), are not regularly used for screening purposes. However, they may be helpful for evaluating women at a higher risk for breast cancer. According to the ACS, women at high risk for breast cancer (for example, women with BRCA gene mutations or a strong family history of breast cancer) should receive MRI screening along with a mammogram. MRI is often better than mammography and ultrasound at finding a small mass in a woman's breast, especially for women with very dense breast tissue. However, an MRI has the risk of having a higher rate of false-positive test results (a test result that indicates cancer when there is no cancer present) and may result in more biopsies and other tests. In addition, an MRI does not show calcifications, which could indicate in situ breast cancer (DCIS).
Ultrasound or MRI may also be used for those with a suspicious finding on physical examination or mammography. If there are suspicious findings on physical examination, further evaluation is necessary, even if the mammogram is interpreted as normal. Women are encouraged to discuss the frequency and method of breast cancer screening with their doctors.