It is generally believed that the chronic infection caused by gallstones stimulates the gallbladder epithelium to proliferate and become cancerous in the long term. It has been reported that the size of gallstones is positively correlated with the chance of gallbladder cancer. It has also been reported that chronic cholecystitis with calcification of the gallbladder wall has a cancer rate of 12.5-61%. A small amount of methylcholanthrene was implanted into the gallbladder of six cats, and five cats developed gallbladder cancer. Cholesterol and bile acid salts in bile can be transformed into chemicals with a chemical structure similar to methylcholanthrene by anaerobic bacteria such as Clostridium perfringens, so it is thought that these carcinogenic factors contained in bile are related to the development of gallbladder cancer. Other people believe that the occurrence of gallbladder cancer is related to the malformation at the junction of the lower part of the common bile duct and the confluence of the main pancreatic duct. It is also believed that the occurrence of gallbladder cancer is the result of various factors such as dietary factors, bacterial and parasitic infections, and gallstones. Bile duct cancer is also closely related to gallstones, and it has been reported that 64-100% of bile duct cancer cases are combined with gallstones, but some believe that bile duct cancer is not as closely related to gallstones as gallbladder cancer. Chronic ulcerative colitis and Schistosoma haematobium infection have been reported to be related to the occurrence of cholangiocarcinoma. Cholangiocarcinoma can occur in about 18% of patients with congenital common bile duct cysts, and the cancer usually occurs in the posterior wall of the cyst or in the bile ducts surrounding the cyst. The relationship between primary sclerosing cholangitis and cholangiocarcinoma is still controversial. Some people believe that primary sclerosing cholangitis itself is a kind of cholangiocarcinoma with low malignancy and slow progression.