A new study has found that the combination therapy of vitamin E, selenium and soy does not prevent the progression from high-grade prostatic intraepithelial neoplasia (HGPIN) to prostate cancer.
For the study, Canadian researchers divided 303 men, with an average age of 62, into two randomized groups.
All participants had HGPIN, a precursor to invasive prostate cancer, as confirmed by a central pathology review in at least one of two biopsies within 18 months prior to randomization.
The combination treatment was administered daily for three years with follow-up prostate biopsies at six, 12, 24 and 36 months. Supplementation was discontinued if a man developed invasive disease.
Researchers found that 26.4 percent of patients developed invasive prostate cancer. Baseline, age, weight and testosterone levels did not predict the development of cancer.
"Unfortunately, as this study shows, we have yet to find a dietary supplement that will reliably prevent prostate cancer. The results of this study support the findings of the SELECT trial which also demonstrated no benefit using Vitamin E and selenium," said Christopher Amling, MD, an AUA spokesman.
"These studies highlight the importance of conducting randomized trials of these agents since many of these supplements are promoted falsely to the general public as having beneficial effects on cancer prevention and progression," he added.
The findings were presented at the 104th Annual Scientific Meeting of the American Urological Association (AUA).