Diethyl-nitrosamine hepatocarcinogenesis in cirrhotic rats.

The aim of this study was to clarify how the CCl4-induced cirrhosis modifies the process of diethylin-nitrosamine hepatocarcinogenesis. Two strains of rats (CFY and F-344) were used. CFY rats proved to be resistant toward both the cirrhogenic effect of CCl4 and carcinogenic effect of DEN. In the F-344 rats, on the other hand, a large number of foci, neoplastic nodules and hepatocellular carcinomas occurred following DEN treatment only and fullblown liver cirrhosis did develop in the CCl4-treated group. In F-344 rats with cirrhotic liver, foci and neoplastic nodules appeared in the usual number and at the usual time following DEN treatment, but--opposite to the expectations--much less carcinomas developed than in the rats receiving DEN only. When, however the CCl4-treatment was applied following the DEN administration, a promoting effect was seen. The mechanism of the inhibitory effect of the CCl4-induced liver cirrhosis upon hepatocarcinogenesis is not clarified, similarly to the mechanism of of the promoting effect of the CCl4-treatment applied following the DEN administration.