Tamoxifen's clinical applications: old and new.

The American Cancer Society estimates that this year more than 180, 000 women in the United States will develop breast cancer and more than 40,000 women will die of the disease. According to a National Cancer Institute model, 5 years of preventive therapy with tamoxifen citrate reduced the risk of invasive breast cancer by 49% (P<.00001) in women at increased risk for breast cancer. The reduction in risk was greater in women with a history of lobular carcinoma in situ (LCIS; 56% relative risk reduction) or atypical hyperplasia (86% relative risk reduction). It should be noted, however, that no benefit was found in 2 European studies using notably different risk evaluation models and entry criteria. Because elevated risks of uterine cancer and thromboembolic disease have been associated with tamoxifen therapy, appropriate counseling should be given to any woman considering tamoxifen as a means of reducing breast cancer risk. Arch Fam Med. 2000;9:906-912