Cigarette smoking, CYP1A1 MspI and GSTM1 genotypes, and colorectal adenomas

Cigarette smoking has been related to increased risk of colorectal adenomas , but the underlying mechanisms are unknown. Genetic polymorphisms are know n for enzymes involved in the activation of polycyclic aromatic hydrocarbon s and other tobacco-related carcinogens, Polycyclic aromatic hydrocarbons a re activated by cytochrome P4501A1 (CYP1A1) and detoxified by glutathione S -transferases, We investigated the relation of CYP1A1 MspI and GSTM1 genoty pes to the risk of colorectal adenomas with special reference to interactio n with cigarette smoking among 205 cases of colorectal adenomas and 220 con trols with normal total colonoscopy in a male Japanese population. Cigarett e smoking was strongly associated with increased risk of colorectal adenoma s, Overall, neither the CYP1A1 MspI genotype nor the GSTM1 genotype was rel ated to colorectal adenomas, A significant trend for increased risk of colo rectal adenomas associated with smoking was observed for each of the CYP1A1 MspI genotypes, and the increasing trends did not differ by MspI genotype, The positive association between smoking and colorectal adenomas did not v ary much with GSTM1 genotypes, Among former and current smokers, adenoma ri sk did not differ according to the combination of CYP1A1 MspI and GSTM1 gen otypes. CYP1A1 MspI and GSTM1 genotypes do not seem to modify the risk of c olorectal adenomas associated with cigarette smoking.