(P13-022-23) Interaction Between Dietary Vitamin E Intake and COMT Gene Polymorphism in Relation to Colorectal Cancer: A Case-Control Study

Objectives: Discordant results in studies investigating the effects of vitamin E on cancer may in part be due to different genetic backgrounds affecting the response to vitamin E intake. Recently, the catechol-O-methyltransferase (COMT) gene has been reported to modify the effect of alpha-tocopherol supplementation on overall cancer incidence. However, the interactive effect of COMT with dietary vitamin E intake on cancer is not yet known. Therefore, we investigated whether the genetic polymorphism in COMT, rs730602, modifies the association between dietary vitamin E intake and colorectal cancer risk.

Methods: In this case-control study of Korean adults, 972 colorectal cancer case patients and 972 controls were frequency-matched by age and sex. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire. Vitamin E density (mg/1,000 kcal) was used to categorize participants into 2 groups by ( >and ≤ median). DNA was isolated from peripheral blood cells and rs740603 was genotyped. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression models after adjustment for potential confounders.

Results: Higher dietary vitamin E density was associated with a reduced risk of colorectal cancer (OR=0.71; 95% CIs=0.58, 0.87). The genotype of rs740603 was not associated with colorectal cancer, but a significant interaction with vitamin E density on colorectal cancer was observed (P-for-interaction=0.04). When stratified by the rs740603 genotype, higher dietary vitamin E density was associated with reduced colorectal cancer risk only in carriers of the major allele A (OR=0.66; 95% CIs=0.53, 0.82) but not in carriers of the homozygous G allele (OR=1.01; 95% CIs=0.59, 1.73).

Conclusions: Dietary vitamin E intake was associated with reduced colorectal cancer risk only among carriers of the rs740603 A allele in Korean adults, supporting a role for COMT in modulating the association between dietary vitamin E intake and colorectal cancer.

Funding Sources: This work was supported by a grant from the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education.