[Role of alcohol-metabolizing enzymes gene polymorphisms and environmental exposure on colorectal cancer: a case-only study].

Objective: This study was designed to explore the interactions of alcohol dehydrogenase 1B (ADH1B) rs1229984, aldehyde dehydrogenase 2 (ALDH2)(rs671) and cytochrome P4502E1(CYP2E1)rs1329149 with environmental factors and the interactions between genetic factors in the susceptibility of colorectal cancer (CRC). Roles of genetic factors in the development of colorectal cancer were also studied.

Methods: With a case-only study design, 472 colorectal cancer cases were enrolled between 2007 and 2009 in this study. Data on demographic characteristics, histories of environmental exposure and clinico-pathological parameters were obtained from all the participants through written questionnaires. Genotypes were determined by Sequenom MassARRAY system. Unconditional logistic regression analysis was employed to explore the gene-environment interactions and gene-gene interactions. χ(2) test and unconditional logistic regression were used to evaluate the roles of polymorphisms on the risk of metastasis to CRC.

Results: Overweighted individuals that carrying at least one of the ADH1B rs1229984 G alleles presented significant increase on the risk to colorectal cancer(OR = 1.720, 95%CI:1.038-2.848,ORadj = 1.785, 95%CI:1.061-3.002). Modest interaction was seen between smoking and ADH1B(rs1229984) only before the adjustment of data, by sex, age and drinking status(OR = 0.597, 95% CI:0.387-0.921, ORadj = 0.922, 95%CI:0.509-1.669). Correlations between polymorphisms and the Dukes stage were not found.

Conclusion: Overweight presented significant interaction with G allele of ADH1B rs1229984 in the susceptibility of CRC. None of the rs1229984, rs671 and rs1329149 exhibited significant influence on the development of CRC.