Ileal resection potentiates 1,2-dimethylhydrazine-induced colonic carcinogenesis.

The effect of colonic hyperplasia produced by resection of the distal third of the small bowel (DSBR) on the development of chemical carcinogenesis of the colon by dimethylhydrazine (DMH) was tested in rats. For the most part the amounts of RNA and DNA in the small bowel were the same with the combined treatments as with either one alone; quantities of nucleic acids tended to increase only in transverse and distal colon. After 37 weeks the number of neoplasms per rat was increased six-fold by combining DSBR with DMH. Neoplasms were spread throughout the colon after combined treatment as opposed to the ascending colong after DMH alone. Postresectional hyperplasia appears to increase the incidence and distribution of colon tumors.