Progression From High-Grade Prostatic Intraepithelial Neoplasia to Cancer: A Randomized Trial of Combination Vitamin-E, Soy, and Selenium

Purpose High-grade prostatic intraepithelial neoplasia (HGPIN) is a putative precursor of invasive prostate cancer (PCa). Preclinical evidence suggests vitamin E, selenium, and soy protein may prevent progression of HGPIN to PCa. This hypothesis was tested in a randomized phase III double-blind study of daily soy (40 g), vitamin E (800 U), and selenium (200 μg) versus placebo. Patients and Methods Three hundred three men in 12 Canadian centers were analyzed. The main eligibility criterion was confirmed HGPIN in at least one of two biopsies within 18 months of random assignment. Treatment was administered daily for 3 years. Follow-up prostate biopsies occurred at 6, 12, 24, and 36 months postrandomization. The primary end point was time to development of invasive PCa. Kaplan-Meier plots and log-rank tests were used to compare two treatment groups for this end point. Results For all patients, the median age was 62.8 years. The median baseline prostate-specific antigen (PSA; n = 302) was 5.41 ug/L; total tes...