In the present study, we examined the relation of CYP1A1, GSTM1, GSTT1 and NQO1 polymorphisms as well as of cigarette smoking to colorectal cancer risk in the Fukuoka Colorectal Cancer Study, a community-based case-control study [35], focusing on the interaction with cigarette smoking and gene-gene interaction. The gene discussed is CYP1A1; the disease is colorectal cancer.