LCN2 and cholangiocarcinoma: In addition, the diagnostic sensitivity, specificity and area under the receiver operating characteristic (ROC) curves of serum NGAL for differentiating cholangiocarcinoma from benign biliary tract disease patients were defined and compared with the values of carbohydrate antigen 19-9 (CA19-9), which is the common marker for cholangiocarcinoma [16, 17].