Breast cancer chemoprevention: progress and controversy.

The chemoprevention of breast cancer using pharmacologic agents has had substantial clinical success. Randomized clinical trials evaluating selective estrogen-receptor modulators (SERMs) have shown that these agents reduce the incidence of breast cancer by up to 50% in healthy women at increased risk for the development of the disease. SERMs have been of particular value in women with biopsy-proven risk factors, including atypical hyperplasia or lobular carcinoma in situ of the breast. The agents of established value are important options for women today, and efforts are under way to identify additional more effective therapies.