Cholangiocarcinoma in Germany: Epidemiologic trends and impact of misclassification.

BACKGROUND & AIMS: Diverging trends of cholangiocarcinoma (CCA) incidence in different countries warrant further subtype-specific characterization. In this study, we aimed to determine current epidemiologic trends of CCA in Germany and evaluated impact of misclassification of perihilar CCA (pCCA) as intrahepatic CCA (iCCA).

METHODS: Subtype-specific incidence was assessed based on data of approximately 40 million German citizens from 2003 to 2014, and mortality data of entire Germany were assessed from 1998 to 2015.

RESULTS: Reclassification of pCCA to extrahepatic CCA (eCCA) led to an enhancement of an increasing average annual percentage change (AAPC) for iCCA in men (3.8 to 4.8) and women (3.3 to 4.8). Likewise, a stable or slightly decreasing trend in extrahepatic CCA was strengthened in women (AAPC: -0.2 to -0.9) and men (1 to 0.5). pCCA accounted for 13% of biliary tract tumours (iCCA: 46%, distal CCA: 41%). In line with incidence trends, mortality of iCCA in Germany increased for women (AAPC 7.8) and men (6.5), while it was stable for eCCA (women: -0.6, men: 2.1).

CONCLUSION: Incidence of iCCA in Germany is increasing while it is stable for eCCA. Misclassification of pCCA as iCCA is present, but clearly declining.