Biliary tract cancers: epidemiology, molecular pathogenesis and genetic risk associations

Abstract: Biliary tract cancers (BTC) are malignancies that arise from the epithelium of the biliary system and comprise the second most common type of hepatobiliary cancer worldwide. BTC are sub-classified as intrahepatic cholangiocarcinoma (iCCA), perhilar/hilar cholangiocarcinoma (pCCA), distal cholangiocarcinoma (dCCA), and gallbladder carcinoma. Due to the differences in their etiologic risk factors, pathogenesis, and molecular and genetic characteristics, each of these subtypes is considered a separate biological entity. The geographic diversity of risk factors for the subtypes of biliary cancers results in profound differences in the worldwide incidence of each. In this article we provide a review of the current epidemiology of BTC and their associated risk factors. Further, we discuss the available evidence for genetic predisposition to BTC and anticipate the results of planned large-scale, genome-wide association studies (GWAS) exploring the inherited sequence variants conferring risk of BTC. These studies may also potentially of reveal important pathogenic mechanisms of the biliary tract cancer subtypes.