Epidemiology; pathogenesis; and classification of cholangiocarcinoma

INTRODUCTION

Cholangiocarcinomas (bile duct cancers) arise from the epithelial cells of the intrahepatic and extrahepatic bile ducts. Although these cancers are rare in the United States, they are highly lethal because most are locally advanced at presentation.

The epidemiology, pathology, pathogenesis, and classification of cholangiocarcinoma will be discussed here. Clinical manifestations, diagnosis, and treatment are reviewed separately. (See "Clinical manifestations and diagnosis of cholangiocarcinoma" and "Treatment of cholangiocarcinoma".)

Cancers of the gall bladder and ampulla of Vater are discussed as separate disease processes, although these structures are part of the biliary drainage system. (See "Gallbladder cancer: Epidemiology, risk factors, clinical features, and diagnosis" and "Ampullary carcinoma: Epidemiology, clinical manifestations, diagnosis and staging".)

ANATOMY, TUMOR CLASSIFICATION AND STAGING

Biliary tract cancers were traditionally divided into cancers of the gallbladder, the extrahepatic ducts, and the ampulla of Vater, while intrahepatic tumors were classified as primary liver cancers. More recently, the term cholangiocarcinoma has been used to refer to bile duct cancers arising in the intrahepatic, perihilar, or distal (extrahepatic) biliary tree, exclusive of the gallbladder or ampulla of Vater (figure 1). Intrahepatic cholangiocarcinomas originate from small intrahepatic ductules (termed peripheral cholangiocarcinomas) or large intrahepatic ducts proximal to the bifurcation of the right and left hepatic ducts. The extrahepatic bile ducts are divided into perihilar (including the confluence itself) and distal segments, with the transition occurring at the point where the common bile duct lies posterior to the duodenum [1].

Bismuth-Corlette classification — Cancers arising in the perihilar region have been further classified according to their patterns of involvement of the hepatic ducts (the Bismuth-Corlette classification) (figure 2) [2]: