Angiopoietin-2 and biliary diseases: elevated serum, but not bile levels are associated with cholangiocarcinoma

The diagnosis of cholangiocarcinoma (CC) is challenging especially in patients with primary sclerosing cholangitis (PSC) and often delayed due to the lack of reliable markers. Angiopoietin-2 (Angpt-2) has been employed as a biomarker of angiogenesis and might be involved in tumor neoangiogenesis. To evaluate the diagnostic potential of Angpt-2 as a biomarker to detect patients with CC. Bile and serum Angpt-2 levels were measured in patients with CC (n=45), PSC (n=74), CC complicating PSC (CC/PSC) (n=11) and patients with bile duct stones (n=37) in a cross sectional study. Diagnostic accuracy of Angpt-2 was compared to carbohydrate antigen 19-9 (CA19-9). Fluorescent immunohistochemistry from human CC liver tissue samples was performed to localize the origin of Angpt-2. Serum Angpt-2 concentration was significantly elevated in patients with CC compared to control patients (p