OBJECTIVE: To review data on the use of tamoxifen for primary prevention of breast cancer. DATA SOURCES: A literature search was performed through MEDLINE (1992–May 2002) using the key words tamoxifen, breast cancer, and prevention. DATA SYNTHESIS: Breast cancer is the most common malignancy detected in American women. Attempts to reduce morbidity and mortality include early detection programs and chemoprevention. Clinical trials of tamoxifen for reduction of breast cancer risk are reviewed. CONCLUSIONS: Tamoxifen may reduce the risk of primary breast cancer in women at increased risk. The benefit of tamoxifen in women who are not at risk is uncertain. The risks of developing thromboembolic disorders or endometrial cancer must be considered before tamoxifen is prescribed. Women should be given all of the information about the benefits and risks of tamoxifen use so that they can make an informed decision based on the best data available.
