MEAT PREPARATION AND COLORECTAL ADENOMAS IN A LARGE SIGMOIDOSCOPY-BASED CASE-CONTROL STUDY IN CALIFORNIA (UNITED-STATES)

The often observed association between red meat and colorectal cancer could be due in part to mutagens, such as heterocyclic amines (HCA), t hat are present in cooked meat. HCAs are highly mutagenic and cause in testinal tumors in animals. The hypothesis that HCAs are also carcinog enic to humans remains to be substantiated in epidemiologic studies. W e determined the associations of meat preparation and frequency of int ake (proxy variables for HCA exposure, since HCA concentration depends on the type of meat and the way it is cooked) with the prevalence of distal colorectal adenomas in a sigmoidoscopy-based case-control study of 488 matched pairs of subjects from two California (United States) Kaiser Permanente Medical Centers. A more than twofold difference in a denoma prevalence between subjects at extreme ends of estimated HCA in take was observed. For subjects who ate red meat more than once per we ek, fried it more than 10 percent of the time, and ate it with a darkl y browned surface, compared with subjects who ate red meat one time or less per week, fried it 10 or less percent of the time, and ate it wi th a lightly browned surface, the odds ratio was 2.2 (95 percent confi dence interval = 1.1-4.3). Adenoma prevalence also increased with freq uency of frying red meat (P trend = 0.004). These results are consiste nt with a carcinogenic effect of HCA.