Xenobiotic Metabolizing Genes, Meat-Related Exposures, and Risk of Advanced Colorectal Adenoma

The potential for carcinogenic action of meat-related exposures, such as heterocy-clic amines (HCAs), polycyclic aromatic hydrocarbons (PAHs), and N-nitroso compounds (NOCs) [1, 2], might explain positive associations between red and processed meat intake and colorectal neoplasia [3]. HCAs and PAHs are formed in meats cooked well-done at high temperatures [4] and produce intestinal tumors in rodents [5, 6, 7]. NOCs are some of the strongest known chemical carcinogens [2] and induce tumors in both the colon and rectum of numerous animal species [8]. Nitrate and nitrite, which are added to processed meats, can form NOCs [9]. NOCs can also form endogenously in the colon through the conversion of nitrate and nitrite [10], a reaction which is thought to be catalyzed by heme iron from red meat [11, 12].