Hormonal effects of toremifene in breast cancer patients

The effect of toremifene treatment on the serum levels of sex steroids (estradiol, progesterone, testosterone), FSH, LH, prolactin, TSH, T3, T4 and SHBG was investigated. Basal prolactin level and the “prolactin reserve capacity” of the hypophysis was also studied by the TRH functional test. Steroid hormone receptors were detected in the patients where a tumor biopsy could be obtained. In a randomized trial patients were treated by 60 and 300 mg of toremifene per os, daily. Hormone levels were assayed prior to treatment and at the 2nd, 6th, 8th and 12th week of toremifene therapy. The hormonal effects of toremifene were the most marked at the 2nd and at the 8th week. Estradiol decreased continuously, SHBG increased slightly and the high initial value of basal prolactin level decreased. The TRH induced prolactin release was suppressed by toremifene after an 8-week period. No clinical response-related tendency was found.