Absolute increase in prostate cancer risk 1.6 per 1,000 person-years with long-term vitamin E
WEDNESDAY, Oct. 12 (HealthDay News) -- Long-term vitamin E supplementation is associated with an increased risk of prostate cancer in healthy men, according to a study published in the Oct. 12 issue of the Journal of the American Medical Association.
Eric A. Klein, M.D., from the Cleveland Clinic, and colleagues investigated the long-term effect of vitamin E and selenium on risk of prostate cancer after the initial report of a statistically nonsignificant increase in prostate cancer risk with vitamin E from the Selenium and Vitamin E Cancer Prevention Trial (SELECT). A total of 34,887 men with no diagnosis of prostate cancer were randomized between August 2001 to June 2004 into one of four treatment groups; oral selenium with matched vitamin E placebo; vitamin E with matched selenium placebo; both agents; or both matching placebos. Incidence of prostate cancer was measured during a seven to 12 year follow-up.
The investigators identified 521 additional prostate cancer cases since the primary SELECT report. Compared with the placebo group, the hazard ratio of developing prostate cancer was 1.17 (95 percent confidence interval [CI], 1.004 to 1.36) in the vitamin E group, 1.09 (95 percent CI, 0.93 to 1.27) in the selenium group, and 1.05 in the vitamin E plus selenium group (95 percent CI, 0.89 to 1.22). The absolute increase in the risk of prostate cancer per 1,000 person-years relative to placebo was 1.6 for vitamin E, 0.8 for selenium, and 0.4 for the combination of vitamin E and selenium.
"Dietary supplementation with vitamin E significantly increased the risk of prostate cancer among healthy men," the authors write.
Several authors disclosed financial relationships with pharmaceutical companies. Study agents and packaging were provided by Perrigo Co., Sabinsa Corp., Tishcon Corp., DSM Nutritional Products Inc., and Wyeth.