Dietary Heterocyclic Amine Intake, NAT2 Genetic Polymorphism, and Colorectal Adenoma Risk: the Colorectal Adenoma Study in Tokyo

Background: While several studies have provided support for a positive association between meat intake and colorectal neoplasia, the role of heterocyclic amines (HCA), which is hypothesized to underline this relation, has been less consistent. We evaluated the association of HCA intake with colorectal adenoma risk in a case-control study in a middle-aged Japanese population.

Methods: Study subjects were 738 patients with adenoma and 697 controls who underwent total colonoscopy between 2004 and 2005 and responded to self-administered lifestyle and dietary questionnaires. HCA exposure concentration was estimated from meat and fish intake based on an HCA database that was validated against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) values measured in human hair. Logistic regression models were used to estimate ORs and 95% confidence interval (CI) for the association between HCA and colorectal adenoma risk after adjusting for potential confounders.

Results: High intake of 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) and total HCA was associated with an increased risk of colorectal adenoma in women but not in men. The multivariate-adjusted OR for the highest versus lowest quartile in women was 2.10 (95% CI, 1.20-3.67; Ptrend = 0.01) for MeIQ and 1.73 (95% CI, 0.99-3.01; Ptrend = 0.03) for total HCA. No clear association with PhIP or 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) estimates and no effect modification by NAT2 acetylation genotype was observed.

Conclusions: This study suggests that high MeIQ and total HCA estimates are positively associated with colorectal adenoma risk.

Impact: The findings add to evidence that HCA may play a role in colorectal carcinogenesis in humans. Cancer Epidemiol Biomarkers Prev; 24(3); 613-20. ©2015 AACR.