Cholangiocarcinoma (CCA) is the second most commonly occurring primary hepatobiliary cancer, accounting for 10%-20% of all primary hepatic carcinomas. 1,2 The 5-year relative survival rates range from 2% to 15% for intrahepatic cholangiocarcinoma (ICC) and 2%-30% for extrahepatic cholangiocarcinoma (ECC). 3 The majority of new CCA patients (60% ~ 70%) are diagnosed at a late stage and are treated with palliative therapy, particularly chemotherapy. 4,5 However, the prognoses remain unsatisfactory in such settings, despite the provision of first-line chemotherapy. When a patient's condition deteriorates following first-line chemotherapy, the recommended approach is supportive care. 6 CCA has low sensitivity to chemotherapy, and only a few effective anticancer drugs are available for its treatment. Traditionally, the occurrence of CCA is considered rare; however, the global incidence rate of the disease, particularly ICC, has steadily increased over the past 15 years. 1,7 Cholangiocarcinoma is commonly classified based on its anatomical site of presentation into the ICC and ECC subtypes. ECC is further divided into perihilar cholangiocarcinoma (PCC) and distal cholangiocarcinoma (DCC), with each subtype showing different epidemiological, molecular and therapeutic characteristics (Figure 1). Although the aetiology of CCA has not been determined, several risk factors have been identified. For example, some risk factors for ICC include primary sclerosing cholangitis (PSC), liver cirrhosis, Opisthorchis viverrine infection and Clonorchis sinensis infection, whereas PSC, gallstones and Lynch syndrome are risk factors for ECC. 8-10 Surgery is currently the most effective and preferred treatment option for CCA. However, surgical resection can be performed in only approximately 35% of patients with early-stage disease. Besides, the rate of post-operative