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Cholangiocarcinoma: Advances in pathogenesis, diagnosis, and treatment

Cholangiocarcinoma (CCA) is an epithelial cancer originating from the bile ducts with features of cholangiocyte differentiation.1 CCA is the second most common primary hepatic malignancy, and epidemiologic studies suggest its incidence is increasing in Western countries.2 Advanced CCA has a devastating prognosis, with a median survival of <24 months.3 The only curative therapy is surgical extirpation or liver transplantation, but unfortunately the majority of patients present with advanced stage disease, which is not amenable to surgical therapies. Anatomically, CCA is classified into extrahepatic and intrahepatic forms of the disease. The extrahepatic form is more common, accounting for 80% to 90% of CCAs. It is further divided into proximal or perihilar and distal subsets depending on the location of the cancer within the extrahepatic biliary system. Perihilar disease is also frequently referred to as a Klatskin tumor. Three different growth patterns of extrahepatic CCA can be observed: (1) periductal infiltrating, (2) papillary or intraductal, and (3) mass forming.4 Intrahepatic CCA typically presents as an intrahepatic mass. In addition to their distinct morphology and clinical presentations, intrahepatic and extrahepatic CCAs differ in etiopathogenesis, molecular signatures, and management. In the last several years there have been significant new insights into the molecular pathogenesis of CCA. New diagnostic and therapeutic modalities have also been developed, resulting in improved detection rates and outcomes. In addition, we have now entered the era of targeted therapies for human cancers. Therefore, it is timely and topical to review these advances with a focus on promising targeted therapies for this disease. An additional goal is to stimulate further interest in this disease with the hope of improving outcomes for this still highly lethal malignancy.