High incidence of biliary tract carcinoma in cases of choledochopancreatic long common channel syndrome (CPLCCS) is now widely recognized including our study which twelve carcinomas were found in 74 cases of CPLCCS. However as to the average age of patients with biliary tract carcinoma, no significant difference was found between patients with CPLCCS and the patient without CPLCCS. As an experimental animal model of CPLCCS, choledochopancreatic end to side ductal anastomosis was successfully performed in one hundred puppies, which pancreatocholedochal reflux occured in all. Histological findings of bile duct wall were mainly hyperplastic one and no malignant change was found. The action of pancreatic juice to the bile duct wall is very mild and chronic, however the postoperative period became longer, the histological changes became more remarkable. Therefore pancreatocholedochal reflux requires either a long time or other etiologic factor (for example a biliary infection) in order to produce a biliary tract carcinoma.
