Using Medication To Prevent Breast Cancer: Recommendations from the United States Preventive Services Task Force FREE

The United States Preventive Services Task Force (USPSTF) is a group of physicians and other health care experts that reviews published research and makes recommendations about preventive health care.

Breast cancer is a common type of cancer among women in the United States. Despite improvements in early detection and treatment, about 39,600 American women will die of breast cancer in 2002. Chemoprevention is a strategy for reducing the risk for cancer (“prevention”) by taking drugs (“chemo”). The drug tamoxifen reduces the risk for a second episode of breast cancer in women who have already had breast cancer. Some evidence indicates that tamoxifen and a similar drug, raloxifene, can prevent breast cancer in women who have never had the disease. Of note, the U.S. Food and Drug Administration has approved only tamoxifen for the prevention of breast cancer. However, these drugs also have side effects that include hot flashes, vaginal discharge, and sexual problems, and they increase the risk for cancer of the uterus, stroke, cataracts, and blood clots. Women must weigh the potential benefits of chemoprevention for breast cancer against these risks of taking the drugs.

The USPSTF reviewed published research to evaluate the benefits and harms of using medication to prevent breast cancer.

The USPSTF found three high-quality studies that used tamoxifen and one that used raloxifene. Taken together, these studies suggest that tamoxifen and raloxifene substantially reduced the risk for a first episode of breast cancer in women who had a 1.66% (1.66 out of 100) or greater risk for developing the disease in the next 5 years. The reduction was only in types of breast cancer that are especially sensitive to estrogens. Both drugs increased the risk for blood clots and hot flashes. Tamoxifen also increased the risk for stroke and cancer of the uterus.

Women at low or average risk for breast cancer should not routinely use tamoxifen or raloxifene to prevent breast cancer. Women with risk factors for breast cancer should discuss the potential benefits and harms of tamoxifen and raloxifene with their doctors. The strongest risk factors for breast cancer are older age; family history of breast cancer in a mother, sister, or daughter; and a breast biopsy that shows an abnormality called atypical hyperplasia. Women can estimate their risk for developing breast cancer in the next 5 years by using the National Cancer Institute Breast Cancer Risk Tool (Available at http://cancer.gov/bcrisktool or by calling 800-4-CANCER). A woman is least likely to suffer the side effects of chemoprevention if she is under age 50, has no special risk for blood clots or stroke, and has no uterus. Women should talk with their physicians about chemoprevention of breast cancer, especially if they are young, at high risk for breast cancer, and at low risk for blood clots.

The Breast Cancer Risk Tool has not been studied in primary care settings. The recommendations are based on relatively few studies of chemoprevention for breast cancer. As more studies become available, the USPSTF may modify these recommendations.