Association between alpha-tocopherol, gamma-tocopherol, selenium, and subsequent prostate cancer.
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.
Helzlsouer
K J
KJ
Department of Epidemiology, The Johns Hopkins School of Hygiene and Public Health, Baltimore, MD 21205, USA. Khelzlso@jhsph.edu
Huang
H Y
HY
Alberg
A J
AJ
Hoffman
S
S
Burke
A
A
Norkus
E P
EP
Morris
J S
JS
Comstock
G W
GW
D000368:Aged; D016022:Case-Control Studies; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011471:Prostatic Neoplasms / Q000097:blood* / Q000209:etiology* / Q000517:prevention & control; D012306:Risk; D012307:Risk Factors; D012643:Selenium / Q000008:administration & dosage* / Q000097:blood*; D014810:Vitamin E / Q000008:administration & dosage* / Q000097:blood*
D014810:Vitamin E; D012643:Selenium