title: Vegetable, fruit and meat consumption and potential risk modifying genes in relation to colorectal cancer.
abstract: Epidemiological evidence shows high red meat consumption to increase the risk of colorectal cancer, while the consumption of fruit and vegetables has been shown to be protective. Many genes have been identified that encode for enzymes involved in the metabolism of dietary carcinogens or anti-carcinogens. A study of 500 incident colorectal cancer cases and population controls, matched for age, sex and general practitioner, was conducted in the United Kingdom to investigate whether 6 such genes (CYP1A1, GSTT1, GSTM1, GSTP1, EPHX1 and NQO1) modify the relationship between diet and disease risk. Usual diet was estimated using a detailed questionnaire administered by interview. Fruit and vegetable consumption were both found to protect against colorectal cancer, while overall meat and red meat consumption were found to increase risk. There was some evidence of interaction between GSTT1 and vegetable consumption (p=0.006, not adjusted for multiple tests) but no evidence of interaction with GSTM1. The protective effect of vegetables was only seen in those with deficient or intermediate GSTT1 predicted phenotype [OR 0.3, 95% confidence interval (0.1, 0.6), and OR 0.6 (0.4, 0.96), OR 1.4 (0.3, 2.4) for those with fast phenotype], and a similar result was observed for cruciferous vegetables. There was also weak evidence of interaction between red meat intake and GSTT1 (p=0.06), GSTP1 (p=0.16, with p=0.02 after adjustment for potential confounders) and NQO1 predicted phenotype (p=0.01). Because of the multiple hypotheses tested in our study, these findings require independent confirmation.
authors.affiliation: Genetic Epidemiology Division, Cancer Research UK Clinical Centre, St. James's University Hospital, Leeds, United Kingdom. faye.turner@cancer.org.uk
authors.forename: Faye
authors.initials: F
authors.lastname: Turner
authors.forename: Gillian
authors.initials: G
authors.lastname: Smith
authors.forename: Christoph
authors.initials: C
authors.lastname: Sachse
authors.forename: Tracy
authors.initials: T
authors.lastname: Lightfoot
authors.forename: R Colin
authors.initials: RC
authors.lastname: Garner
authors.forename: C Roland
authors.initials: CR
authors.lastname: Wolf
authors.forename: David
authors.initials: D
authors.lastname: Forman
authors.forename: D Timothy
authors.initials: DT
authors.lastname: Bishop
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Barrett
mesh_terms: D000368:Aged; D002273:Carcinogens / Q000378:metabolism; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000209:etiology* / Q000235:genetics*; D004032:Diet; D005260:Female; D005638:Fruit; D020022:Genetic Predisposition to Disease; D005838:Genotype; D005982:Glutathione Transferase / Q000235:genetics* / Q000494:pharmacology; D006801:Humans; D008297:Male; D008660:Metabolism; D008875:Middle Aged; D010641:Phenotype; D012307:Risk Factors; D006113:United Kingdom; D014675:Vegetables
chemical_list: D002273:Carcinogens; C413545:glutathione S-transferase T1; D005982:Glutathione Transferase