Enhancement of diethylnitrosamine hepatocarcinogenesis in rats by exposure to polychlorinated biphenyls or phenobarbital.

Diethylnitrosamine (DENA) hepatocarcinogenesis was enhanced by sequential exposure with polychlorinated biphenyls (PCBs) and with phenobarbital. This was shown by the earlier appearance of tumors and a significant increase in the number of tumors. However, there was no evidence suggesting an acceleration of tumor growth.