About 1/3 of bile duct cancer patients are combined with bile duct stones, and 5%~10% of bile duct stone patients will develop bile duct cancer, which indicates that prolonged stimulation of bile ducts by stones and proliferative changes of epithelium may be related to the occurrence of bile duct cancer. 2, Schistosoma oryzae In Southeast Asia, eating raw fish infected with Schistosoma oryzae leads to biliary tract infection, bile stagnation, fibrosis around bile ducts and bile duct hyperplasia, which is one of the factors leading to the occurrence of cholangiocarcinoma. People who eat nitrite-rich food habits are more likely to induce cancer. 3.Cystic Dilatation of Bile Duct Cancer occurs in a few patients with Cystic Dilatation of Bile Duct. Stone formation within the cyst, bacterial infection, especially the reflux of pancreatic fluid due to the abnormal development of the confluence part, are the main reasons leading to the development of cancer. Primary sclerosing cholangitis has been reported to be a precancerous lesion of cholangiocarcinoma.