Comparative clinicopathological study of resected intrahepatic cholangiocarcinoma in northeast Thailand and Japan

Northeast Thailand has a very high incidence of intrahepatic cholangiocarcinoma (ICC), which is closely linked to infestation by the liver fluke, whereas the etiology of ICC in Japan remains to be clarified. This study compared the clinicopathological features, the expression of p53 and c-erbB-2 proteins, and the proliferative activity of ICC in 19 Thai and 23 Japanese patients with ICC who were treated by hepatic resection. The average age of the Thai patients (55.8 years) was lower than that of the Japanese (61.3 years). All Thai patients presented with symptoms, whereas 8 Japanese patients were asymptomatic. There were no significant differences in preoperative liver function test values. Tumors were less likely to be located in the right lobe in the Japanese (34.8%) than in the Thai patients (63.2%). Peribiliary fibrosis and adenomatous hyperplasia in noncancerous hepatic tissues were much more frequently found in the Thai patients (P = 0.0010; P < 0.0001). No significant differences in the expression of p53 protein or c-erbB-2 protein were found between the two series of patients, but proliferative activity, evaluated on the basis of mean MIB1 labeling index, was significantly higher in the Thai patients (P < 0.001). The present study suggested a higher proliferative activity of ICC in Thai patients than in Japanese patients.