Prostate Cancer Prevention Study Suspended

(October 29, 2008) - A large study to see if vitamin E and selenium would prevent prostate cancer has been ended early. (Read about "Vitamins & Minerals" "The Prostate") Initial, independent review of study data from the Selenium and Vitamin E Cancer Prevention Trial (SELECT) shows that selenium and vitamin E supplements, taken either alone or together, did not prevent prostate cancer.

The data also showed two trends officials are concerned about:

• 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
• a small, but not statistically significant increase in the number of cases of adult onset diabetes in men taking only selenium (link to i05)

Because this is an early analysis of the data from the study, officials stress that 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 gathering blood samples.

Neither the men nor their physicians know which supplements or placebos the men have been taking, a procedure known as blinding or masking. As followup of the SELECT participants continues, the participants will continue to be blinded. However, at the request of a participant, they will be informed which supplement, if any, they received.