Association Between - Tocopherol , - Tocopherol , Selenium , and Subsequent Prostate Cancer

Background: Selenium and -tocopherol, the major form of vitamin E in supplements, appear to have a protective effect against prostate cancer. However, little attention has been paid to the possible role of -tocopherol, a major component of vitamin E in the U.S. diet and the second most common tocopherol in human serum. A nested case–control study was conducted to examine the associations of -tocopherol, -tocopherol, and selenium with incident prostate cancer. Methods: In 1989, a total of 10 456 male residents of Washington County, MD, donated blood for a specimen bank. A total of 117 of 145 men who developed prostate cancer and 233 matched control subjects had toenail and plasma samples available for assays of selenium, -tocopherol, and -tocopherol. The association between the micronutrient concentrations and the development of prostate cancer was assessed by conditional logistic regression analysis. All statistical tests were two-sided. Results: The risk of prostate cancer declined, but not linearly, with increasing concentrations of -tocopherol (odds ratio highest versus lowest fifth = 0.65; 95% confidence interval = 0.32–1.32; Ptrend = .28). For -tocopherol, men in the highest fifth of the distribution had a fivefold reduction in the risk of developing prostate cancer than men in the lowest fifth (Ptrend = .002). The association between selenium and prostate cancer risk was in the protective direction with individuals in the top four fifths of the distribution having a reduced risk of prostate cancer compared with individuals in the bottom fifth (Ptrend = .27). Statistically significant protective associations for high levels of selenium and -tocopherol were observed only when -tocopherol concentrations were high. Conclusions: The use of combined and tocopherol supplements should be considered in upcoming prostate cancer prevention trials, given the observed interaction between -tocopherol, -tocopherol, and selenium. [J Natl Cancer Inst 2000; 92:2018–23]