Dr. Eric A. Klein of the Cleveland Clinic in Ohio and colleagues examined the long-term effect of vitamin E and selenium on risk of prostate cancer in relatively healthy men.
From August 2001 to June 2004, the men in the United States, Canada and Puerto Rico were randomized into four groups -- one group got selenium 200 micrograms/day of selenium, another got 400 International Units of vitamin E a day, a third group got both and the fourth group got a placebo. Follow-up was from seven years to 12 years.
Since the initial report, 521 prostate cancers have been diagnosed -- 113 in the placebo group, 147 in the vitamin E group, 143 in the selenium group, and 118 in the combination group.
The study, published in the Journal of the American Medical Association, found the rate of prostate cancer detection was greater in all groups compared with placebo but was statistically significant only in the vitamin E alone group -- which had a 17 percent increased rate of prostate cancer detection.
The difference in rates of prostate cancer between vitamin E and placebo became apparent during the participants' third year in the trial and was consistent across both low- and high-grade disease, the study said.