Progress in interventional therapy of extrahepatic cholangiocarcinoma

Extrahepatic cholangiocarcinoma refers to a malignant tumor originating from the extrahepatic bile duct, including the bile duct from the hilar area to the lower end of the common bile duct. In the 8th edition of American Joint Committee on Cancer (AJCC) guideline, extrahepatic cholangiocarcinoma is classified into two parts: hilar and distal parts. In recent years, the incidence of extrahepatic cholangiocarcinoma has gradually increased, and the prognosis has been poor. The limitations of traditional surgical resection in treatment have gradually manifested. In the diagnosis of cholangiocarcinoma, carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) are not specific and are only used as a reminder of changes in the condition for patients, which facilitates timely adjustment of treatment. Imaging examinations such as computed tomography (CT)/magnetic resonance imagining (MRI) can be used for multi-phase comparison to achieve the purpose of diagnosis. MRCP also plays an important role in the diagnosis of extrahepatic cholangiocarcinoma. At present, hepatectomy or cholangioectomy is the conventional surgical treatment for hilar cholangiocarcinoma. For distal cholangiocarcinoma, pancreaticoduodenectomy can be performed to achieve the purpose of treatment. However, due to the limitations of traditional surgery, extrahepatic cholangiocarcinoma with metastasis can not be effectively controlled. Therefore, with the development of interventional technology, interventional therapy for unresectable extrahepatic cholangiocarcinoma will become a new trend. In recent years, biliary drainage, radiofrequency ablation of the biliary tract, biliary stents, radioactive particles implantation and transhepatic artery intervention have become more and more mature in the treatment of cholangiocarcinoma. Recent research hotspots include biliary drainage of cholangiocarcinoma and improving cholestasis. The current commonly used interventional treatment methods include bile duct drainage, radiofrequency ablation and local radiotherapy and chemotherapy. Among them, biliary drainage includes percutaneous transhepatic biliary drainage (PTBD), endoscopic nasobiliary drainage (ENBD) and percutaneous transhepatic biliary stenting (PTBS) are effective in relieving the condition and treating biliary obstruction; in addition, radiofrequency ablation generates heat through high-frequency current, which can achieve the purpose of killing tumors. In recent years, transarteria