Effects of Long-Term Administration of Tamoxifen on Steroid Metabolism in Prostatic Carcinoma Patients

Six patients with advanced prostatic carcinoma were treated with tamoxifen (2 X 20 mg daily) for up to 3 months before orchiectomy. Blood samples for gonadotropin, sex steroid, and prostate-specific acid phosphatase (PAP) determinations were taken before tamoxifen treatment, daily for 1 week, and at monthly intervals. Steroid concentrations in the testis tissue and spermatic vein blood were assayed from samples taken at orchiectomy. No consistent changes were observed during tamoxifen treatment, although there was a transient drop in the mean concentrations of LH on days 3 and 4 of treatment. The circulating concentrations of estradiol tended to be increased at 1, 2, and 3 months of treatment. The spermatic vein concentrations of testosterone and its precursors tended to be higher than those in nontreated prostatic carcinoma patients previously reported from this laboratory, indicating slight stimulation of testicular steroidogenesis. There were no changes in circulating levels of PAP and no improvement in clinical condition, indicating that long-term tamoxifen administration is not effective in the treatment of prostate carcinoma.