fig1

Figure 1. Illustration of the anatomical sites of BTC includes intrahepatic cholangiocarcinoma (iCCA), perihilar cholangiocarcinoma (pCCA), and distal cholangiocarcinoma (dCCA). iCCA refers to malignancies located in the periphery of the second-order bile ducts, while pCCA originates in the right or left hepatic duct and/or at their junction. On the other hand, dCCA involves the common bile duct. Each subtype of BTC occupies a distinct anatomical position within the biliary tract. The collective term extrahepatic cholangiocarcinoma (eCCA) is used to encompass both pCCA and dCCA.