J Natl Cancer Inst 2000 Dec 20;92(24):2018-2023

Association Between alpha-Tocopherol, gamma-Tocopherol, Selenium, and
Subsequent Prostate Cancer.

Helzlsouer KJ, Huang HY, Alberg AJ, Hoffman S, Burke A, Norkus EP, Morris JS,
Comstock GW

K. J. Helzlsouer, H.-Y. Huang, A. J. Alberg, S. Hoffman, A. Burke, G. W.
Comstock, Department of Epidemiology, The Johns Hopkins School of Hygiene and
Public Health, Baltimore, MD.

[Record supplied by publisher]

BACKGROUND: Selenium and alpha-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 gamma-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 alpha-tocopherol, gamma-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, alpha-tocopherol, and gamma-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 alpha-tocopherol (odds ratio (highest versus lowest fifth) = 0.65; 95% confidence interval = 0.32-1.32; P:(trend) =.28). For gamma-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 (P:(trend) =.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 (P:(trend) =.27). Statistically significant protective associations for high levels of selenium and alpha-tocopherol were observed only when gamma-tocopherol concentrations were high.

CONCLUSIONS: The use of combined alpha- and gamma- tocopherol supplements should be considered in upcoming prostate cancer prevention trials, given the observed interaction between alpha-tocopherol, gamma-tocopherol, and selenium.