An article published in the May 1, 2009 issue of the journal Cancer Research reported the discovery of researchers at the National Cancer Institute of an improvement in prostate cancer survival among men with high vitamin E levels. The effect was particularly strong among those who supplemented with the vitamin.

Joanne L. Watters and colleagues analyzed data from 29,133 participants in the Alpha-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Study, which evaluated the effect of vitamin E and beta-carotene on the risk of cancer in male Finnish smokers enrolled between 1985 and 1988. Blood samples collected upon enrollment and at three years were analyzed for serum levels of beta-carotene, retinol (vitamin A), and alpha-tocopherol (vitamin E). Although the trial concluded in April, 1993, on-going follow-up documented 1,891 prostate cancer cases and 395 deaths due to the disease through April, 2005.

Men whose serum alpha-tocopherol levels at the beginning of the study were among the top one-fifth of participants were found to have a 33 percent lower risk of dying of prostate cancer compared with those whose levels were in the lowest fifth. For those whose levels were highest at the third year of the study, a 20 percent lower risk existed. Men who received alpha-tocopherol supplements in the trial and whose baseline levels of vitamin E were highest experienced the lowest risk of prostate cancer mortality, which was 49 percent less than the risk experienced by those in the lowest 20 percent of serum alpha-tocopherol levels. This risk declined after three years to 74 percent less than the risk of those among the lowest fifth.

When all-cause mortality was analyzed among those diagnosed with prostate cancer, participants in the top one-fifth of serum vitamin E levels were shown to have a 33 percent lower risk of death over the course of follow-up, suggesting, according to the authors, "a possible effect for alpha-tocopherol on other causes of death in men with prostate cancer."

In their discussion, the authors note that the current study's findings are at odds with those of the Physician's Health Study II and the Selenium and Vitamin E Cancer Prevention Trial which failed to find a benefit for vitamin E on prostate cancer survival and incidence. The current study's analysis of serum alpha-tocopherol levels and longer follow-up period could account, in part, for the variance.

"These findings build upon previous research showing a 41 percent reduction of prostate cancer mortality in response to alpha-tocopherol supplementation in the controlled trial component of the ATBC Study from 1985 to 1993," the authors write. "In summary, our results suggest dietary and supplemental alpha-tocopherol may improve prostate cancer survival. Considering the large number of men diagnosed with prostate cancer, such nutritional modifications could have a significant effect if subsequent randomized trials in men with newly diagnosed prostate cancer prove a benefit," they conclude.