Antiestrogen-induced remissions in premenopausal women with stage IV breast cancer: Effects on ovarian function

Tamoxifen (T) was given in doses of 40-120 mg/day to 11 premenopausal women with stage IV breast cancer. Objective remission occurred in five, the disease did not progress in one, and five failed to respond. Duration of remission is 19+ months. Five patients underwent ovariectomy after receiving T: of two who responded to T and then relapsed, one responded to ovariectomy. The effect of T on the menstrual cycle ranged from no effect to complete cessation of menses, usually observed in patients who received larger doses. T induced a marked rise in serum estrone and estradiol, reaching levels up to 2500 pg/ml; serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels remained in the normal premenopausal range or were slightly elevated. In two patients in whom amenorrhea was induced with larger doses of T, both serum estrogen and gonadotropin levels were elevated. We conclude that T is effective in treating premenopausal patients with stage IV breast cancer. Because of the stimulating effect of T on ovarian function, escalated doses of T or castration plus T may be necessary in those patients who respond to T.