Postmenopausal carcinoma as a result of estrogen treatment: survey of evidence.

Recent studies concerning the relationship of exogenous estrogens and endometrial cancer have been reviewed and the objections to their conclusions discussed. Even considering the most serious of these reservations, it is difficult to avoid the tentative conclusion that estrogens are causally linked to endometrial cancer and that the attributable risk is numerically sizable. Whether the medical costs will be ultimately shown to outweigh the benefits of estrogen replacement therapy will depend largely on whether or not a relationship to breast cancer is shown and on the magnitude of the effect of estrogens in preventing serious complications of ovarian failure. For the time being, treatment of menopausal symptoms with estrogens should be brief as possible, should use the lowest dose possible, and should probably be given in cyclic fashion, particularly to women with intact uteruses. Every attempt should be made to give patients a quantitative understanding of both potential risks and benefits before they decide in favor of or against estrogen therapy.