Meat intake, preparation methods, mutagens and colorectal adenoma recurrence.

Red meat intake has been shown to be associated with higher risk of colorectal cancer. Though the exact mechanisms responsible for this association remain unknown, several tumorigenic properties of meat have been proposed. One well-supported biologic mechanism is elevated exposure to the genotoxic formation of heterocyclic amines (HCAs), which occur when meat is cooked at high temperatures for a long period of time. We prospectively assessed the relation between type of meat, meat preparation method, doneness, a metric of HCAs and other mutagens and colorectal adenoma recurrence among 869 participants in a chemoprevention trial of ursodeoxycholic acid. Unconditional logistic regression analyses were used to estimate odds ratios (ORs) and associated 95% confidence intervals (CIs). Most meat variables assessed were positively but weakly associated with recurrence of any adenoma. In contrast, recurrence of advanced or multiple adenomas was more strongly associated with a number of the meat exposure variables evaluated. For recurrence of advanced lesions, significant associations were detected among individuals in the highest when compared with the lowest tertile of intake for pan-fried red meat (OR = 1.85; 95% CI = 1.10-3.13) and well/very well done red meat (OR = 1.71; 95% CI = 1.02-2.86). Significant positive associations were shown for recurrence of multiple adenomas and the following variables: processed meat (OR = 1.83; 95% CI = 1.10-3.04), pan-fried red meat (OR = 1.63; 95% CI = 1.01-2.61), well/very well done red meat (OR = 1.68; 95% CI = 1.03-2.74), 2-amino-3,4,8-trimethylimidazo[4,5,-f]quinoxaline (OR = 1.74; 95% CI = 1.07-2.82) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (OR = 1.68; 95% CI = 1.03-2.75). Our results support a meat mutagen exposure hypothesis as a potential mechanism for recurrence of clinically significant adenomatous polyps.