Colorectal Polyp Type and the Association With Charred Meat Consumption, Smoking, and Microsomal Epoxide Hydrolase Polymorphisms

Abstract

We determined the association between charred meat consumption, cigarette smoking, microsomal epoxide hydrolase (mEH) polymorphisms (rs1051740 and rs2234922), and colorectal adenomas and hyperplastic polyps (HPs) and explored gene–environment interactions. Men and women with colorectal adenomas (n = 519), HPs (n = 691), or concurrently with both types of polyps (n = 227) and polyp-free controls (n = 772) receiving a colonoscopy from December 2004 to September 2007 were recruited. Participants completed telephone interviews and provided buccal cell samples; genotyping of mEH was completed using Taqman assays. We conducted polytomous regression and calculated odd ratios (OR) and 95% confidence intervals. Interactions were evaluated using Wald chi-square tests. Consumption of >3 servings of charred meat per week was associated with distal HPs (OR = 2.0, 1.2–3.4) but not adenomas nor either type of proximal polyp. Heavy cigarette smoking (≥ 22 pack-years) was associated with an increased risk for colorectal adenomas (OR = 1.7, 95% CI: 1.2–2.4), HPs (OR = 2.4, 95% CI: 1.7–3.3), and both types (OR = 2.8, 95% CI: 1.8–4.3) with the strongest association for distal polyps. There was no association between mEH genotype and colorectal polyps, nor were any statistically significant gene–environment interactions identified. Future investigation of BaP exposure and colorectal neoplasia should analyze whether associations are dependent upon anatomic location.

ACKNOWLEDGMENTS

This research was funded by National Institute of Health Grants R01 CA 074794, R25 CA94880 (to SVA and MS), and T32 CA09168-32 (to ABH). We would like to acknowledge Dr. Elena Kuo for project management at Group Health, the late Dr. Jeremy Jass for his many contributions, Drs. Lee-Ching Zhu and Melissa Upton for providing pathological expertise, and Dr. John Potter for his advice in all stages of this study.