Cholangiocarcinomas (CCAs) are rare tumors that originate from cholangiocytes in the bile ducts and are classified as intra- or extrahepatic (ICC or ECC). ICCs account for 10–12％ of liver cancers, while ECCs account for approximately one-third of biliary tract cancers (1). Incidence rates of CCA are geographically variable, with the highest rates in Asia. However, even in the highest incidence country (South Korea) the rates are only 2.8 and 2.2 per 100,000 person-years for ICC and ECC, respectively (2). Incidence rates of both ICC and ECC have been increasing in most countries globally, which potentially indicates a changing etiology (2).