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The SELECT Prostate Cancer Prevention Trial
    Posted: 07/24/2001    Updated: 12/02/2008


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Prostate Cancer Study Shows No Benefit for Selenium, Vitamin E

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NCI's gateway for information about prostate cancer.

SELECT (the Selenium and Vitamin E Cancer Prevention Trial) is the largest-ever prostate cancer prevention trial. Previous studies suggested that selenium and vitamin E (alone or in combination) might reduce the risk of developing prostate cancer by 60 percent and 30 percent, respectively, but only a large clinical trial such as SELECT could confirm those initial findings.

Initial independent review of study data from SELECT, carried out in September and October of 2008, shows that selenium and vitamin in E supplements, taken either alone or together for an average of five years, did not prevent prostate cancer. The data also showed two concerning trends: a small increase in the number of prostate cancer cases in men taking only vitamin E and a small increase in the number of cases of diabetes in men taking only selenium. Neither of these findings proves an increased risk from the supplements and may be due to chance. These initial results were published by the Journal of the American Medical Association online on December 9, 2008 (see the abstract).

In October 2008, participants were told to stop taking their study supplements. They will continue to have their health monitored by study staff for about three years, including prostate cancer screening tests. This additional follow up will help to determine the long-term effects of having taken either supplement or placebo and will help to complete a biorepository of blood samples that will be used in extensive molecular analyses of prostate cancer, other cancers, and other diseases of men's aging.

SELECT began enrolling patients on August 22, 2001, and closed enrollment on June 24, 2004, with 35,534 participants. About 15 percent of the participants are African-American. The study includes men 55 and older. African-American men, 50 and over, were eligible to enroll because prostate cancer strikes African-American men earlier and more often than white men. There are more than 400 SELECT sites throughout the United States, Puerto Rico, and Canada.

Coordinated by a network of researchers called the Southwest Oncology Group (SWOG), the study is sponsored by the National Cancer Institute (NCI).

SWOG maintains a Web page with information about SELECT.

To get more information about SELECT, call 1-800-4-CANCER in the United States and Puerto Rico or 1-888-939-3333 in Canada.

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