The thalidomide analog, EM 12, enhances 1,2-dimethylhydrazine-induction of rat colon adenocarcinomas

Young male Sprague-Dawley rats in 3 groups were fed a basal diet supplemented with 0.10 wt. % each of thalidomide and its imide-analog of much higher teratogenicity, EM 12. Following an induction period of 17 days on the diets, all animals were injected subcutaneously with 1,2-dimethylhydrazine at 20 mg/kg for a total of 20 weekly doses and killed on week 18 after the 20th injection. The total number of colon adenocarcinomas and their occurrence in the proximal and distal portions for the thalidomide-treated rats were similar to those of the respective controls. However, the EM 12-fed group elicited statistically significant increases both in the total and ascending colon-based adenocarcinomas as compared with the control findings, in keeping with its greater teratogenicity and embryotoxicity. The numbers of small intestinal adenocarcinomas were equally higher in the imide-fed groups in contrast to the control frequency.