Selective Estrogen Receptor Modulation and Reduction in Risk of Breast Cancer, Osteoporosis, and Coronary Heart Disease

The recognition of selective estrogen receptor modulation in the laboratory has resulted in the development of two selective estrogen receptor modulators (SERMs), tamoxifen and raloxifene, for clinical application in healthy women. SERMs are antiestrogenic in the breast but estrogen-like in the bones and reduce circulating cholesterol levels. SERMs also have different degrees of estrogenicity in the uterus. Tamoxifen is used specifically to reduce the incidence of breast cancer in premenopausal and postmenopausal women at risk for the disease. In contrast, raloxifene is used specifically to reduce the risk of osteoporosis in postmenopausal women at high risk for osteoporosis. The study of tamoxifen and raloxifene (STAR) trial is currently comparing the ability of these SERMs to reduce breast cancer incidence in high-risk postmenopausal women. There is intense interest in understanding the molecular mechanism(s) of action of SERMs at target sites in a woman's body. An understanding of the targeted actions of this novel drug group will potentially result in the introduction of new multifunctional medicines with applications as preventive agents or treatments of breast cancer and endometrial cancer, coronary heart disease, and osteoporosis.