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December 10, 2008
Early Released JAMA Antioxidant Studies on Prostate Cancer have Similar Limitations, Says Association
Results of PHS II and SELECT clinical trials available online.
On December 9, 2008, The Journal of the American Medical Association (JAMA) published two early release articles and an editorial on antioxidant supplementation. The first early release article titled “Vitamins E and C in the Prevention of Prostate and Total Cancer in Men: The Physicians' Health Study II (PHS II) Randomized Controlled Trial” reports on the effect of long-term supplementation of vitamins C and E on the risk of prostate or total cancer. Results of the “Physicians Health Study II” specific to cardiovascular disease were previously released by JAMA in November. In the November 10, 2008 issue of the Natural Products Association Supplement the association previously commented on the limitations of the Physicians Health Study II and its design.
In response to findings in the second early release study in JAMA called “Effect of Selenium and Vitamin E on Risk of Prostate Cancer and Other Cancers: The Selenium and Vitamin E Cancer Prevention Trial (SELECT),” Daniel Fabricant, Ph.D., the association’s vice president of scientific and regulatory affairs, issued these comments:
"Unfortunately, there is no sure-fire method to prevent prostate cancer, and if we are going to look at nutritional intervention in a phase III drug model as was the case in the SELECT trial, then we need to have good data from phase I and II style trials. This would include single and multiple ascending dose studies that are necessary to understand how much of the intervention should be given to see efficacy and how well the intervention works at a prescribed dose. Neither was performed prior to this study. Additionally, and similar to the PHS II, we have no way of knowing the effect food is playing in the study; food intake isn't controlled. We get selenium and vitamin E from food and there are foods that may exhibit differences in absorption of the intervention by the body. So, there are a variety of possibilities that may be affecting actual intake of vitamin E and selenium."
The results of both the PHS II and the SELECT clinical trial are available online at http://www.jama.ama-assn.org/
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