Genetic Polymorphisms of CYP2E1 and Risk of Colorectal Adenomas in the Self Defense Forces Health Study

CYP2E1 is an enzyme involved in the metabolism of N -nitrosamines and other carcinogenic substances. Functional Rsa I and 96-bp insertion polymorphisms in 5′-flanking region have drawn interest in relation to the risk of colorectal cancer. We investigated the relation of these genetic polymorphisms and colorectal adenoma, a well-established precursor lesion of colorectal cancer. Subjects were 455 cases of colorectal adenomas and 1,052 controls of normal colonoscopy among men receiving a preretirement health examination in the Self Defense Forces. Genotypes were determined by either PCR-RFLP or PCR method. Statistical adjustment was made for smoking, alcohol use, body mass index, physical activity, and others. Individuals with Rsa I c2 allele showed a decreased risk of proximal colon adenomas; adjusted odds ratios (95% confidence interval) of proximal and distal adenomas for the c1/c2 or c2/c2 genotype versus c1/c1 was 0.61 (0.41-0.88) and 0.95 (0.71-1.27), respectively. CYP2E1 96-bp insertion allele was associated with an increased risk of large (≥ 5 mm) adenomas; adjusted odds ratios (95% confidence interval) of large and small adenomas for having at least one insertion allele were 1.41 (1.03-1.94) and 0.94 (0.71-1.25), respectively. A suggestive effect modification was noted for alcohol consumption on the association between Rsa I polymorphism and proximal adenomas ( P interaction = 0.09) as well as on the association between 96-bp insertion and large adenomas ( P interaction = 0.05). These findings indicate that variation in activity and inducibility of CYP2E1 contribute to the development of colorectal carcinogenesis. (Cancer Epidemiol Biomarkers Prev 2008;17(7):1800–7)