The effects of short-term oral phytoestrogen supplementation on the hypothalamic-pituitary-testicular axis in prostate cancer patients

BACKGROUND: Here we evaluate the effects of oral phytoestrogen supplementation on hypothalamic-pituitary-testicular (HPT) axis in CaP patients. METHODS: We recruited 40 men about to undergo radical prostatectomy for CaP to receive either 240 mg of clover phytoestrogens or placebo daily for 2 weeks. Serum hormone levels were measured before and after treatment. In addition, recombinant cell bioassay was used to measure serum androgen bioactivity (ABA). RESULTS: Phytoestrogen treatment increased serum LH from mean of 3.4-5.2 IU, P = 0.03. Concomitantly, non-significant trend towards decline in serum T, cfT and ABA values was noted. However, mean serum LH/T ratio was upregulated from 0.20 to 0.48 IU/nM, P = 0.004, suggesting compensated hypogonadism. During the course of treatment, serum concentration of equol correlated strongly with the concomitant decrease in ABA (r = -0.586, P = 0.022). CONCLUSIONS: Phytoestrogen treatment interferes with HPT axis in CaP patients by inducing testicular resistance to LH and compensated hypogonadism.