Dietary benzo[a]pyrene intake and risk of colorectal adenoma.

We carried out a clinic-based case-control study specifically designed to address the hypothesis that dietary intake of polycyclic aromatic hydrocarbons (PAH) is associated with colorectal adenoma risk. We developed a food frequency questionnaire with detailed questions on meat-cooking methods and doneness levels and a benzo[a]pyrene (BaP) database (as a surrogate for total carcinogenic PAHs) based on the collection and analysis of a wide range of food samples. We estimated BaP intake derived from meat and from all foods to test its relationship with risk of colorectal adenomas. The median (10th and 90th percentiles) BaP intake in controls was 5 ng/d (0.2 and 66 ng/d) estimated from meat and 73 ng/d (35 and 140 ng/d) from all foods. In cases, median BaP intake was 17 ng/d (0.5 and 101 ng/d) from meat and 76 ng/d (44 and 163 ng/d) from all foods. Multivariate analysis was carried out on 146 cases and 228 controls. The odds ratios (95% confidence interval) for dietary BaP from meat with the first quintile as the reference group were 1.19 (0.51-2.80) for the second quintile, 1.71 (0.76-3.83) for the third quintile, 2.16 (0.96-4.86) for the fourth quintile, and 2.82 (1.24-6.43) for the fifth quintile (Ptrend=0.01). Increased risk of colorectal adenomas was more strongly associated with BaP intake estimated from all foods: 2.61 (1.08-6.29) for the second quintile, 4.21 (1.79-9.91) for the third quintile, 2.45 (0.98-6.12) for the fourth quintile, and 5.60 (2.20-14.20) for the fifth quintile (Ptrend=0.002). This study provides evidence that dietary BaP plays a role in colorectal adenoma etiology.