title: Microsomal epoxide hydrolase polymorphisms and risk for advanced colorectal adenoma.
abstract: Cigarette smoking is a risk factor for colorectal adenoma, a precursor of colorectal cancer. Microsomal epoxide hydrolase (EPHX1) metabolizes polycyclic aromatic hydrocarbons, carcinogens found in cigarette smoke. Nonsynonymous variants of EPHX1 at Tyr(113)His (exon 3) and His(139)Arg (exon 4) are associated, respectively, with low ((113)His) and high ((139)Arg) predicted activity. Among participants randomized to the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we evaluated risks for advanced adenoma in relation to cigarette use and these two EPHX1 variants. We compared 772 cases with advanced adenoma (adenoma >/=1 cm or containing high-grade dysplasia or villous, including tubulovillous, elements) of the distal colon (left-sided, descending colon and sigmoid or rectum) to 777 gender- and age-matched controls who were screen-negative for left-sided adenoma. Compared to those with homozygous genotypes predicting low EPHX1 activity, advanced adenoma risks tended to be elevated for carriers of (113)TyrTyr [odds ratios (OR), 1.5; 95% confidence intervals (CI), 1.0-2.2] and (139)ArgArg (OR, 1.4; 95% CI, 0.8-2.5) and for subjects who carried a greater number of the alleles ((113)Tyr or (139)Arg) associated with high predicted enzymatic activity (P(trend) = 0.03). The increased risk associated with the increasing number of putative high-activity alleles was most apparent among current and recent (quit <10 years) cigarette smokers (P(trend) = 0.02). In conclusion, EPHX1 variants at codon 113 and 139 associated with high predicted enzymatic activity appear to increase risk for colorectal adenoma, particularly among recent and current smokers.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, EPS 8113, MSC 7240, Bethesda, MD 20892, USA. huangw@mail.nih.gov
authors.forename: Wen-Yi
authors.initials: WY
authors.lastname: Huang
authors.forename: Nilanjan
authors.initials: N
authors.lastname: Chatterjee
authors.forename: Stephen
authors.initials: S
authors.lastname: Chanock
authors.forename: Michael
authors.initials: M
authors.lastname: Dean
authors.forename: Meredith
authors.initials: M
authors.lastname: Yeager
authors.forename: Robert E
authors.initials: RE
authors.lastname: Schoen
authors.forename: Li-Fang
authors.initials: LF
authors.lastname: Hou
authors.forename: Sonja I
authors.initials: SI
authors.lastname: Berndt
authors.forename: Sunita
authors.initials: S
authors.lastname: Yadavalli
authors.forename: Christine C
authors.initials: CC
authors.lastname: Johnson
authors.forename: Richard B
authors.initials: RB
authors.lastname: Hayes
mesh_terms: D000236:Adenoma / Q000209:etiology / Q000235:genetics*; D000368:Aged; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D015179:Colorectal Neoplasms / Q000209:etiology / Q000235:genetics*; D004851:Epoxide Hydrolases / Q000235:genetics* / Q000378:metabolism; D005091:Exons; D005260:Female; D005838:Genotype; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D011795:Surveys and Questionnaires
chemical_list: D004851:Epoxide Hydrolases