SELECT: Selenium, vitamin E show no benefit in prostate cancer prevention

November 6, 2008

Selenium and vitamin E supplements, taken either alone or together, do not appear to prevent prostate cancer, according to an initial, independent review of study data from the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

Selenium and vitamin E supplements, taken either alone or together, do not appear to prevent prostate cancer, according to an initial, independent review of study data from the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

The data also showed two concerning trends: a small but not statistically significant increase in the number of prostate cancer cases among the more than 35,000 men age 50 years 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, according to the authors.

“SELECT was always designed as a study that would answer more than a single question about prostate cancer,” said Eric Klein, MD, of the Cleveland Clinic Glickman Urological and Kidney Institute, who is study co-chair for SELECT. “As we continue to monitor the health of these 35,000 men, this information may help us understand why two nutrients that showed strong initial evidence to be able to prevent prostate cancer did not do so.”

SELECT, which is funded by the National Cancer Institute, is coordinated by the Southwest Oncology Group at more than 400 clinical sites in the United States, Puerto Rico, and Canada. SELECT participants are receiving letters explaining the study review and instructing them to stop taking their study supplements. Participants will continue to have their health monitored by study staff.

Investigators intend to follow the participants for about 3 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, according to an NCI statement.