Receiver operating characteristic (ROC) curve analysis of CEACAM6 to evaluate presence of cholangiocarcinoma. The ROC analysis of all cholangiocarcinomas is depicted by graph A. with a resultant Area Under the Curve (AUC) of 0.738. Graphs B and C respectively illustrate the intrahepatic and extrahepatic subtypes with corresponding AUCs of 0.663 and 0.791.