New data released from the Selenium and Vitamin E Cancer Prevention Trial (SELECT) shows men who took daily doses of vitamin E had significantly more prostate cancers compared to men who took a placebo.
SELECT, a cancer prevention trial funded by the National Institutes of Health (NIH), closed in September 2008, with initial findings indicating no reduction in the risk of prostate cancer for participants using selenium or vitamin E supplements. Early results also suggested that there was a possible relationship between vitamin E and prostate cancer that might have been due to chance.
Recent findings published in the Oct. 12 issue of the Journal of the American Medical Association paint a different picture.
Almost three years after the trial recommended that participants stop using the supplements for lack of evidence of benefit, further analysis revealed a 17 percent increase in prostate cancers among men who took vitamin E supplement compared to participants receiving a placebo.
"The findings are important because we now know for sure that there is no benefit for men who take vitamin E supplements," said Elise Cook, M.D, associate professor of Clinical Cancer Prevention and co-investigator on the study at The University of Texas MD Anderson Cancer Center. "Vitamin E does not prevent prostate cancer, and appears to not only increase the risk of prostate cancer, but in some cases it increases the risk of heart failure and mortality in patients with coronary artery disease."
Of the 427 study sites in the United States, Canada and Puerto Rico, MD Anderson, was one of 36 National Cancer Institute-designated cancer centers that participated in the national trial.
Earlier studies indicated that vitamin E, selenium or a combination of the two might prevent prostate cancer. SELECT - one of the largest cancer chemoprevention trials ever conducted - randomized over 35,000 healthy men ages 50 and older. MD Anderson investigators recruited 387 participants to the trial. Of these, 32 developed prostate cancer, three of whom were in the vitamin E arm of the trial, and 294 agreed to stay on centralized follow-up after the trial closed.
Participants were followed for almost six years after receiving either, selenium and a placebo that resembled vitamin E, vitamin E and a placebo of selenium, two placebos, or a combination of both supplements.
Further research is needed
"It is evident from the results that further research in prostate cancer prevention is needed" says Cook.
Prostate cancer continues to be the second most common type of cancer among men in this country resulting in more than 30,000 deaths annually, according to the National Cancer Institute.
For more information about the SELECT study, participants should contact 1-877-798-5444 or in Spanish call 1-877-740-3331.
For more information about MD Anderson, please contact askMDAnderson at 1-877-632-6789.
National Institutes of Health news release
NIH Q&A about SELECT trial