Metabolic effects of tamoxifen in postmenopause.

Tamoxifen is actually considered the drug of choice for the hormonal treatment of early and metastatic breast cancer due to its efficacy and low toxicity. In addition, clinical trials of adjuvant therapy have demonstrated a 35% decrease in controlateral breast cancer in women receiving tamoxifen compared with controls, suggesting a potential role for this drug in chemoprevention of breast cancer in healthy women at increased risk of disease. Although tamoxifen is usually classified as an estrogen antagonist it also has partial estrogenic effects in some tissues such as liver, bone and uterus. The estrogenic action of tamoxifen on lipid metabolism and bone mineral density suggests additional benefits in protection against cardiovascular diseases and osteoporosis in postmenopausal women. Of particular interest could be the use of tamoxifen as an alternative to traditional estrogen replacement therapy in postmenopausal women previously treated for breast cancer or at increased risk of disease due to family history or histology on breast biopsy. The potential adverse effects of tamoxifen are partially similar to those of ERT and includes an increased risk of endometrial cancer, hepatic diseases, thromboembolic alterations and ocular toxicity. The mechanism of action of tamoxifen is briefly examined and the potential toxic effects and benefits of tamoxifen treatment are discussed.