Lippman SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009 Jan 7;301(1):39-51.
A randomized, placebo-controlled trial Selenium and Vitamin E Prevention Trial [SELECT]) was conducted to determine whether selenium, vitamin E, or both could prevent prostate cancer and other diseases in relatively healthy men. The study involved 35,533 men from 427 participating sites in the United States, Canada, and Puerto Rico who were randomly assigned to 4 groups selenium, vitamin E, selenium + vitamin E, and placebo) in a double-blind manner. Eligibility criteria included the age of 50 years or older (African American men) or 55 years or older (all other men), a serum prostate-specific antigen level of 4 ng/mL or less, and a digital rectal examination that was not suspicious for prostate cancer. Subjects were given oral selenium (200 microg/d from L-selenomethionine) and vitamin E placebo, vitamin E (400 IU/d of all rac-alpha-tocopheryl acetate) and selenium placebo, selenium + vitamin E, or placebo + placebo. A follow-up of minimum of 7 years and a maximum of 12 years was planned. The main outcome measures were prostate cancer and prespecified secondary outcomes including lung, colorectal, and overall primary cancer.
At the median overall follow-up of 5.46 years, the hazard ratios (99% confidence intervals [CIs]) for prostate cancer were 1.13 (99% CI, 0.95-1.35; n = 473) for vitamin E, 1.04 (99% CI, 0.87-1.24; n = 432) for selenium, and 1.05 (99% CI, 0.88-1.25; n = 437) for selenium + vitamin E vs 1.00 (n = 416) for placebo. There were no significant differences (all P>.15) in any other cancer end points. The increased risks of prostate cancer in the vitamin E group (P = .06) and type 2 diabetes mellitus in the selenium group (relative risk, 1.07; 99% CI, 0.94-1.22; P = .16) but not in the selenium + vitamin E group were statistically insignficant.
The authors concluded that selenium or vitamin E, alone or in combination at the doses and formulations used, did not prevent prostate cancer in this population of relatively healthy men.