October 12, 2011
Updated Results From SELECT Prostate Cancer Prevention Study: Increased Prostate Cancer Risk From Vitamin E Supplements
Men who took 400 international units of vitamin E daily had more prostate cancers compared to men who took a placebo, according to an updated review of data from the Selenium and Vitamin E Cancer Prevention Trial (SELECT). The findings showed that, per 1,000 men, there were 76 prostate cancers in men who took only vitamin E supplements, vs. 65 in men on placebo over a 7‑year period, or 11 more cases of prostate cancer per 1,000 men. This represents a 17 percent increase in prostate cancers relative to those who took a placebo. This difference was statistically significant and therefore is not likely due to chance. The results of this update appeared October 12, 2011, in the Journal of the American Medical Association.
SELECT researchers are now measuring the amount of vitamin E, selenium, and other nutrients in the blood of participants when they joined the trial, to see if the effect of the supplements depended upon this baseline level of micronutrient. Other researchers are looking at single nucleotide polymorphisms, which are DNA changes known as SNPs, to see if a change in one or more genes could affect cancer risk or perhaps increase a man’s risk of developing prostate cancer while taking vitamin E.
October 28, 2008
Review of SELECT Prostate Cancer Prevention Study Shows No Benefit for Use of Selenium and Vitamin E Supplements
Initial, independent review of study data from the Selenium and Vitamin E Cancer Prevention Trial (SELECT), funded by the National Cancer Institute (NCI) and other institutes that comprise the National Institutes of Health shows that selenium and vitamin E supplements, taken either alone or together, did not prevent prostate cancer. The data also showed two concerning trends: a small but not statistically significant increase in the number of prostate cancer cases among the over 35,000 men age 50 and older in the trial taking only vitamin E and a small, but not statistically significant increase in the number of cases of adult onset diabetes in men taking only selenium. Because this is an early analysis of the data from the study, neither of these findings proves an increased risk from the supplements and both may be due to chance.
SELECT participants are receiving letters explaining the study review and telling them to stop taking their study supplements. Participants will continue to have their health monitored by study staff, which may include regular digital rectal exams and PSA (prostate-specific antigen) tests to detect prostate cancer. Investigators intend to follow the participants for about three years to determine the long-term effects of having taken either supplement or placebo and to complete a biorepository of blood samples that will be used in extensive molecular analyses to give researchers a better understanding of prostate cancer, other cancers, and other diseases of male aging. This additional data collection is a vital part of the study.
Results of the HOPE-TOO Study (Heart Outcomes Prevention Evaluation Study Extension)
A report published in the March 16, 2005 issue of the Journal of the American Medical Association finds no clear evidence that men and women who had vascular disease or diabetes and who took 400 i.u. of vitamin E daily for 7 years reduced their risk of cancer compared to others with these conditions who took a placebo. The study was not large enough to determine if vitamin E could prevent specific cancers.
The report also showed that those taking vitamin E had a 13 percent increased risk of heart failure, a condition in which the heart’s ability to pump blood is weakened. The report comes from a clinical trial called the Heart Outcomes Prevention Evaluation Study Extension (HOPE-TOO).
These results emphasize the need to study vitamins and other natural products prior to making public health recommendations.