[Animal experiments on the etiology and histogenesis of colonic carcinoma]

The influence of nutrition upon the etiology and histogenesis of dimethylhydrazine induced carcinomas of the colon was studied in rats. A double-way Anus praeter was made in one-half of the animals (393/823). Histological and statistical analysis of more than 7000 organ preparations yielded the following results: (1) The intestinal contents has effects on localization, latency, and frequency of the colonic tumour. (2) When maintained on a protein-rich diet, rats with Anus praeter developed intestinal carcinomas more frequently and earlier than the corresponding controls, or with other dietary regimens under otherwise equal conditions. (3) In rats with Anus praeter the inflammatory stimulus on the ectopied mucosa exerted a stronger co-carcinogenic effect than the intestinal contents. (4) The genetic predisposition of the organ plays an important role in tumorigenesis. (5) In no case did intestinal carcinomas develop de novo, that is, from the unaltered, intact intestinal mucosa. (6) DMH induced carcinomas of the colon was solitary in 46% of the cases, and multiple in 54%. Histological differences within the same carcinoma (10% of the cases) are also indicative of a frequent, multicentric genesis of colonic carcinomas. (7) The significance of submucous, lymphocytic plaques for the immunological defense system requires further experimental clarification. (8) Polyps of the colon are a potential, but no necessary, intermediate from of cancerization.