(ChemotherapyAdvisor) – An additional 54,464 person-years of follow-up since the primary report of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) confirms vitamin E dietary supplementation significantly increases prostate-cancer risk among healthy men, investigators reported during the 2012 Genitourinary Cancers Symposium.

Initial results from SELECT, which analyzed 34,887 men randomly assigned to selenium (n=8752), vitamin E (n=8737), selenium plus vitamin E (n=8702), or placebo (n=8696), found no reduction in risk of prostate cancer with either selenium or vitamin E; however, a nonstatistically significant increase in prostate cancer risk was observed with vitamin E, Eric A. Klein, MD, of the Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, and colleagues reported.

The men enrolled in the study between August 2001 and June 2004 were age 50 years or older (African Americans) or 55 years or older (all others) and had a PSA <4.0ng/mL and a digital rectal examination not suspicious for prostate cancer. The follow-up data were collected on study participants through July 5, 2011.

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Hazard ratios and number of cases of prostate cancer were 1.17 for those in the vitamin E group (P=0.008, n=620); 1.09 for selenium (P=0.18, n=575), 1.05 for selenium plus vitamin E (P=0.46, n=555) and 1.00 for placebo (n=529). Absolute increase in risk vs. placebo was 1.6 cases of prostate cancer per 1,000 person-years for vitamin E; this risk was 0.9 for selenium and 0.4 for the combination.

The 2012 Genitourinary Cancers Symposium is sponsored by the American Society of Clinical Oncology, American Society for Radiation Oncology, and the Society of Urologic Oncology.