Tamoxifen therapy of metastatic breast cancer

Inhibition of estrogen action at the target tissue level with the antiestrogen, tamoxifen, has proved highly successful in the treatment of hormone-responsive breast cancer. In randomized clinical trials involving postmenopausal patients, tamoxifen has been found to be as effective as high-dose estrogens, androgens, progestins, and the aromatase inhibitor, aminoglutethimide. Because of its remarkable lack of significant toxicity, tamoxifen is now considered the first endocrine treatment of choice of hormone-responsive postmenopausal breast cancer. Although effective in a significant fraction of premenopausal patients, tamoxifen cannot be considered a substitute for ovariectomy because it usually does not suppress menses and because response to castration may occur after progression during antiestrogen therapy. Current evidence suggests that there is no major advantage in combining tamoxifen with other endocrine therapies or chemotherapy. At present, it appears preferable to use different modalities of endocrine therapy sequentially in those patients with hormone-responsive cancers. Chemotherapy should be delayed until maximum benefit has been obtained from endocrine therapy.