CHOLANGIOCARCINOMA - EPIDEMIOLOGY, MECHANISMS OF CARCINOGENESIS AND PREVENTION

Cholangiocarcinoma is a relatively rare cancer; worldwide it accounts for an estimated 15% of liver cancers. In most areas, the etiology is rather obscure, and identified risk factors such as hepatolithiasis, i nflammatory bowel disease, and exposure to Thorotrast can account for only a small proportion of cases. In certain areas of southeast and ea stern Asia, however, incidence rates are very high, and here there is a strong association with infection with the liver flukes Clonorchis s inensis and Opisthorchis viverrini. The mechanisms of carcinogenesis i n O. viverrini infection have been the subject of considerable researc h; it seems that the presence of parasites induces DNA damage and muta tions as a consequence of the formation of carcinogens/free radicals a nd of cellular proliferation of the intrahepatic bile duct epithelium. Preventive strategies in areas endemic for liver flukes appear straig htforward, but breaking the cycle of infection has proved difficult in practice.