Prevention

Currently, there are no proven means to prevent breast cancer. A woman's best chance of surviving breast cancer is early detection through regular self-breast examinations, clinical breast examinations, and mammograms (x-rays of the breast). If cancer is found at an early stage, treatment is more likely to be successful.

• For women with especially strong family histories of breast cancer, 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%.
  
  
• Women who are at higher than normal risk for developing breast cancer may consider chemoprevention (the use of drugs to reduce breast cancer risk). One such drug is tamoxifen (Nolvadex), which is a selective estrogen receptor modulator (SERM). A SERM is a medication that blocks estrogen receptors in some tissues and not others. Tamoxifen can reduce a woman’s risk of developing breast cancer and the risk of the cancer recurring once a woman has been treated for breast cancer. Like estrogen, tamoxifen helps increase bone density in postmenopausal women and protects the cardiovascular system. Unlike estrogen, SERMs do not promote the development of breast cells into cancer cells; however, they may increase the risk of blood clots and uterine (endometrial) cancer.

For most women, regular mammography and clinical breast examinations (examinations by a doctor or other health-care professional) can help find early signs of breast cancer. In addition, women should become familiar with their own breasts. Checking your own breasts for lumps with breast self-examination may help if performed correctly. Talk with your doctor for more information.

The STAR trial

The Study of Tamoxifen and Raloxifene (STAR) trial, launched in May 1999, is a breast cancer risk reduction clinical trial. A clinical trial is a research study involving people. The STAR trial compared tamoxifen and raloxifene (Evista) in reducing the risk of breast cancer in postmenopausal women over age 35 who have an increased risk of developing breast cancer. The clinical trial was conducted by the National Cancer Institute and the National Surgical Adjuvant Breast and Bowel Project. A recent analysis of the clinical trial data shows that both tamoxifen and raloxifene reduce the risk of invasive breast cancer by about 50% in women at high risk for the disease (this is the relative risk; the absolute risk for any woman taking these medications to lower the risk of breast cancer is 2% to 3%). Raloxifene does not lower the risk of noninvasive breast cancer. Neither drug significantly impairs quality of life. Because these drugs are associated with different side effects, women should discuss the risks and benefits of each drug with their doctors.

Screening guidelines

The U.S. Preventive Services Task Force (USPSTF) recommends that women 40 to 75 years old undergo mammography every one to two years, and the American Cancer Society (ACS) recommends yearly mammography. Mammography is the best tool doctors have to screen for breast cancer and can detect a tumor that is too small to be felt. All women should talk with their doctors about mammography and decide on an appropriate screening schedule.

Occasionally, mammograms may miss a cancer. 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, including women with a mutation in one of the breast cancer genes (BRCA1 and BRCA2), and women who received radiation therapy for Hodgkin lymphoma. These other screening methods may also be used when there is a suspicious finding on physical examination. If there are suspicious findings on physical examination, further evaluation is necessary, even if the mammogram is interpreted as normal.

The USPSTF and ACS differ on their recommendations for clinical breast examination. The USPSTF recommends a clinical breast examination along with mammography, and the ACS recommends a clinical breast examination every one to three years. 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. Women are encouraged to discuss the frequency of screening with their doctors.