Vitamin E, Selenium and Soy Won't Prevent Prostate Cancer

May 2 -- FRIDAY, May 1 (HealthDay News) -- Despite earlier promise, three nutrients - vitamin E, selenium and soy - do not seem to prevent prostate cancer in men with precancerous prostate lesions, Canadian researchers report.

"There has been a collection of scientific data that has suggested that these agents could have a tremendous impact in preventing prostate cancer," said lead researcher Dr. Neil E. Fleshner, a Clinical Studies Resource Centre Member at the Ontario Cancer Institute and Love Chair in Prostate Cancer Prevention at the University of Toronto.

"So there was great hope that this would be a magic bullet that would help prevent prostate cancer," he said. "Unfortunately, it doesn't appear to be so."

The report was to be presented Sunday at the American Urological Association's annual meeting, in Chicago.

For the study, Fleshner's team randomly assigned 303 men with high-grade prostatic intraepithelial neoplasia (precancerous lesions) to receive soy protein, vitamin E and selenium, or a placebo. Over three years, the men had several biopsies to determine if they had developed prostate cancer.

Just over 26 percent of the men did develop invasive prostate cancer. However, the three nutrients did not seem to minimize that risk, the team found.

"To recommend soy and these supplement to men with high-grade prostatic intraepithelial neoplasia really doesn't make much sense, if the reason you are giving it is to prevent your patient from developing invasive cancer," Fleshner concluded.

He did leave the door open to using these supplements to prevent prostate cancer before precancerous lesions have formed. "In pre-cancer, the cells may already be so damaged that supplements can't reverse the changes," he reasoned. "Or maybe it just doesn't work."

The results confirm the findings of the two recent prospective trials, which also found that vitamin E, vitamin C and selenium do not prevent prostate cancer. The results of these trials were published in the Jan. 7 issue of the Journal of the American Medical Association. Other recent studies have suggested that vitamins, B, C, D, E, folic acid and calcium taken alone, or in various combinations, aren't effective for cancer prevention.