1 Introduction Biliary tract cancer (BTC) encompasses a group of highly aggressive malignant tumors originating from the biliary tree, including intrahepatic duct, extrahepatic bile duct, and gallbladder carcinoma (GBC) (1). Extrahepatic CCAs (eCCAs) are further classified into perihilar and distal CCAs according to anatomical location (2). Recent data indicate a rise in the global incidence (3–5), accompanied by a poor prognosis that 5-year overall survival rates range from 5% to 15% (6, 7).
