Soy Supplementation Fails to Reduce Risk for Prostate Cancer Recurrence

Given the geographic disparity of prostate-cancer incidence, a number of factors may affect risk for the disease, including diet. For example, in much of Asia, incidence of prostate cancer is relatively low compared with the U.S., but consumption of soy-based foods is relatively high. To determine whether soy protects against prostate cancer, U.S. investigators assessed disease recurrence in patients who consumed a daily soy supplement after radical prostatectomy. Prostate-specific antigen (PSA) recurrence was used as a surrogate for clinical benefit.

A total of 177 patients with locally advanced disease (defined using standard criteria) were randomized in double-blind fashion to receive a daily beverage containing 20 grams of protein from a…