High-fat diet promotes and causes distal shift of experimental rat colonic cancer--beer and alcohol do not.

Intestinal cancer was induced in inbred male D/A rats by 1,2-dimethylhydrazine, and the interrelationships between a high-fat (33.5% w/w) diet, beer and alcohol (4.8% v/v) ingestion, and tumor location and incidence were examined. The number of tumors per animal was significantly greater in both the small and large intestines of rats on the high-fat diet, as opposed to the standard diet. The 6-fold increase in incidence of colorectal cancer occurred almost exclusively in the distal half of the large bowel; i.e., there was a highly significant (p less than 0.005) shift, similar to that seen in man in countries adopting high-fat Western-type diets. Neither alcohol nor beer ingestion affected the incidence of intestinal cancers, but beer was associated with a more distal distribution of small-intestinal cancers in animals on the high-fat diet. However, this was not considered sufficient evidence for any material effect of beer on experimental intestinal carcinogenesis.