FEEDING OF A WELL-COOKED BEEF DIET CONTAINING A HIGH HETEROCYCLIC AMINE CONTENT ENHANCES COLON AND STOMACH CARCINOGENESIS IN 1,2-DIMETHYLHYDRAZINE-TREATED RATS

Epidemiologic studies have linked the consumption of red meat and the consumption of highly Drowned meats containing high levels of heterocy clic aromatic amines (HCAs) to increased risk of colorectal cancer or polyps. The present study determined the effects of long-term feeding of beef-contaning diets with low and high levels of HCAs (in the conte xt of a low or high beef fallow diet) on a standard 1,2-dimethylhydraz ine (DMH)-induced colon tumorigenesis protocol. Very lean beef was coo ked by a variety of methods at different temperatures, and the levels of the major HCAs (2-amino-3,8-dirmethylimidazo[4, 5-f]quinoxaline, 2- amino-3,4,8-trimethylimidazo[4, 5-f]quinoxaline, and 2-amino-1-methyl- 6-phenylimidazo[4,5-f]pyridine) were measured by high-performance liqu id chromatography. Diets incorporating beef containing low or high lev els of HCAs were fed for 12 weeks, during which DMH tvas administered to induce colon tumors, followed by various dietary regimens as promot ional stimuli. Feeding of a beg diet high in HCAs resulted in more DMH -induced colon adenocarcinomas, but only in the context of a low-fat d iet. The high-HCA diets increased stomach tumors in all DMH-treated ra ts. An apparent interaction of high HCA with a high fat level reduced the colon tumor incidence and tumor numbers in those diets containing both factors. These results support the epidemiologic data linking wel l-cooked meat to increased risk for colon and stomach cancer, but the role of dietary fat level remains puzzling.