Journal
JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION
Volume 301, Issue 1, Pages 52-62Publisher
AMER MEDICAL ASSOC
DOI: 10.1001/jama.2008.862
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Funding
- National Institutes of Health (Bethesda, Maryland) [CA 97193, CA 34944, CA 40360, HL 26490, HL 34595]
- BASF Corporation (Florham Park, New Jersey)
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Context Many individuals take vitamins in the hopes of preventing chronic diseases such as cancer, and vitamins E and C are among the most common individual supplements. A large- scale randomized trial suggested that vitamin E may reduce risk of prostate cancer; however, few trials have been powered to address this relationship. No previous trial in men at usual risk has examined vitamin C alone in the prevention of cancer. Objective To evaluate whether long- term vitamin E or C supplementation decreases risk of prostate and total cancer events among men. Design, Setting, and Participants The Physicians' Health Study II is a randomized, double- blind, placebo- controlled factorial trial of vitamins E and C that began in 1997 and continued until its scheduled completion on August 31, 2007. A total of 14 641 male physicians in the United States initially aged 50 years or older, including 1307 men with a history of prior cancer at randomization, were enrolled. Intervention Individual supplements of 400 IU of vitamin E every other day and 500 mg of vitamin C daily. Main Outcome Measures Prostate and total cancer. Results During a mean follow- up of 8.0 years, there were 1008 confirmed incident cases of prostate cancer and 1943 total cancers. Compared with placebo, vitamin E had no effect on the incidence of prostate cancer ( active and placebo vitamin E groups, 9.1 and 9.5 events per 1000 person- years; hazard ratio [ HR], 0.97; 95% confidence interval [ CI], 0.85- 1.09; P=. 58) or total cancer ( active and placebo vitamin E groups, 17.8 and 17.3 cases per 1000 person- years; HR, 1.04; 95% CI, 0.95- 1.13; P=. 41). There was also no significant effect of vitamin C on total cancer ( active and placebo vitamin C groups, 17.6 and 17.5 events per 1000 person- years; HR, 1.01; 95% CI, 0.92- 1.10; P=. 86) or prostate cancer ( active and placebo vitamin C groups, 9.4 and 9.2 cases per 1000 person- years; HR, 1.02; 95% CI, 0.90- 1.15; P=. 80). Neither vitamin E nor vitamin C had a significant effect on colorectal, lung, or other site- specific cancers. Adjustment for adherence and exclusion of the first 4 or 6 years of follow- up did not alter the results. Stratification by various cancer risk factors demonstrated no significant modification of the effect of vitamin E on prostate cancer risk or either agent on total cancer risk. Conclusions In this large, long- term trial of male physicians, neither vitamin E nor C supplementation reduced the risk of prostate or total cancer. These data provide no support for the use of these supplements for the prevention of cancer in middle- aged and older men. Trial Registration clinicaltrials. gov Identifier: NCT00270647.
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