Dietary Phytoestrogens and Prostate Cancer Prevention.

摘要

The main objective of this project is to evaluate the effects of soy phytoestrogens on reproductive hormones and prostate tissue markers of cell proliferation and androgen action in men at high risk of prostate cancer. The hypothesis is that alteration of endogenous hormones is a mechanism by which soy phytoestrogens prevent prostate cancer. A randomized parallel arm study is being performed, in which 63 men at high risk of prostate cancer are randomized to receive one of three dietary supplements for six months: 1) soy powder containing phytoestrogens; 2) phytoestrogen-free soy powder; or 3) phytoestrogen-free milk powder. Urine and blood is collected at 0, 3 and 6 mo, for evaluation of serum hormones (testosterone, dihydrotestosterone, androstenedione, dehydroepiandrosterone, estradiol, estrone, 3 ,17 - androstanediol glucuronide, sex hormone binding globulin) and prostate specific antigen, as well as urinary estrogen and phytoestrogen metabolites. At 0 and 12 mo, prostate biopsies are performed to evaluate prostate tissue expression of apoptosis (TUNEL assay, Bax, Bcl-2), proliferation (Ki67, PCNA), and androgen receptor density. A pilot study is being performed to evaluate effects on protein expression in biopsy tissue and phytoestrogen levels in expressed prostatic secretion and post-massage urine. The main study is complete: one manuscript has been accepted for publication, two other are under revew, and one is preparation. The pilot study is continuing with funding from the University of Minnesota.