Vitamin E, C Dont Reduce Risk of Prostate Cancer

BOSTON—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. The Physicians' Health Study II (PHS II) long-term trial of male physicians found neither vitamin E nor C supplementation reduced the risk of prostate or total cancer (JAMA. 2009;301(1)) (DOI:10.1001/jama.2008.862). The randomized, double blind, placebo-controlled factorial trial of vitamins E and C began in 1997 and continued until its scheduled completion on Aug. 31, 2007. A total of 14,641 male physicians in the United States initially aged 50 years or older, including 1,307 men with a history of prior cancer at randomization, were enrolled. Individual supplements of 400 IU of vitamin E every other day and 500 mg/d of vitamin C were administered.

During a mean follow-up of eight years, there were 1,008 confirmed incident cases of prostate cancer and 1,943 total cancers. Compared with placebo, vitamin E had no effect on the incidence of prostate cancer (P=0.58) or total cancer (P=0.41). There was also no significant effect of vitamin C on total cancer (P=0.86) or prostate cancer (P=0.80). 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 four or six 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. These data provide no support for the use of these supplements for the prevention of cancer in middle-aged and older men.