Perihilar cholangiocarcinoma: a surgeon's viewpoint on current topics.

Perihilar cholangiocarcinomas are defined anatomically as "tumors that are located in the extrahepatic biliary tree proximal to the origin of the cystic duct". However, as the boundary between the extrahepatic and intrahepatic bile ducts is not well defined, perihilar cholangiocarcinomas potentially include two types of tumors: one is the "extrahepatic" type, which arises from the large hilar bile duct, and the other is the "intrahepatic" type, which has an intrahepatic component with the invasion of the hepatic hilus. The new TNM staging system published by the International Union Against Cancer (UICC) has been well revised with regard to perihilar cholangiocarcinoma, but it still lacks stratification of patient prognosis and has little applicability for assessing the feasibility of surgical treatment; therefore, further refinement is essential. Most patients with perihilar cholangiocarcinomas present with jaundice, and preoperative biliary drainage is mandatory. Previously, percutaneous transhepatic biliary drainage was used in many centers; however, it is accepted that endoscopic naso-biliary drainage is the most suitable method of preoperative drainage. Portal vein embolization is now widely used as a presurgical treatment for patients undergoing an extended hepatectomy to minimize postoperative liver dysfunction. The surgical resection of a perihilar cholangiocarcinoma is technically demanding and continues to be the most difficult challenge for hepatobiliary surgeons. Because of advances in diagnostic and surgical techniques, surgical outcomes and survival rates after resection have steadily improved. However, survival, especially for patients with lymph node metastasis, is still unsatisfactory, and the establishment of adjuvant chemotherapy is necessary. Further synergy of endoscopists, radiologists, oncologists, and surgeons is required to conquer this intractable disease.