Comparison of liver cancer and nodules induced in rats by deoxycholic acid diet with or without prior initiation.

The neoplastic responses of liver to prolonged continuous exposures of deoxycholic acid (DCA) in the diet with or without prior initiation was examined in Fischer 344 (F-344) and Sprague-Dawley (SD) male rats. In both rat strains, 7 months of continuous feeding of 0.5% (F-344 rats) or 1.0% (SD rats) of deoxycholic acid in chow diet generated hepatic nodules which persisted up to 8 months after deoxycholic acid was stopped. In one group of Sprague-Dawley male rats, 7 months of deoxycholic acid was preceded by an initiating dose of diethylnitrosamine. In 10 out of 15 of these rats, not only persistent nodules but also 26 liver cancers (large, multifocal, invasive, lung metastases) become evident by 8 months after cessation of deoxycholic acid.