Promoting role of Clonorchis sinensis infection on induction of cholangiocarcinoma during two-step carcinogenesis.

Chronic Clonorchis sinensis (CS) infection is etiologically related to cholangiocarcinoma (CHCA) in human and animals. This study was carried out to clarify the role of CS infection on dimethylnitrosamine (DMN)-induced cholangiocarcinogenesis. Fifteen hamsters were administered with 15 ppm DMN for 4 weeks and one week later, the hamsters were infected with 15 metacercariae of CS (DMN-->CS group). The other 15 hamsters were infected with CS and after 5 weeks they were treated with the drug, praziquantel. Again one week later, the hamsters were administered with DMN (CS-->DMN group). The other 15 hamsters were administered with DMN and CS simultaneously (CS+DMN group). Histopathological examination of the livers showed CHCA with papillary or adenomatous hyperplasia of bile ductules in 3 of 15 hamsters of DMN-->CS group and in 11 of 15 hamsters of DMN+CS group. These results suggest that CS infection to hamsters may have a promoting effect on the development of CHCA.