Utility of serum CA19-9 in diagnosis of cholangiocarcinoma: In comparison with CEA

AIM: The diagnosis of cholangiocarcinoma is often difficult, making management approaches problematic. A reliable serum marker for cholangiocarcinoma would be a useful diagnostic test. The aims of our study were to evaluate the usefulness of a serum CA19-9 determination in the diagnosis of cholangiocarcinoma. METHODS: We prospectively measured serum CA19-9 and CEA concentrations in patients with cholangiocarcinoma (n=35), benign biliary diseases (n=92), and healthy individuals (n=15). Serum CA19-9 and CEA concentrations were measured by an immunoradiometric assay without knowledge of the clinical diagnosis. RESULTS: The sensitivity of a CA19-9 value >37 KU/L(-1) and a CEA value >22 microg/L(-1) in diagnosing cholangiocarcinoma were 77.14% and 68.57%, respectively. When compared with the benign biliary diseases group, the true negative rates of serum CA19-9 and CEA were 84.78% and 81.52%, respectively. The false positive rates of serum CA19-9 and CEA were 15.22% and 18.48%, whereas the accuracy of serum CA19-9 and CEA were 82.68% and 77.95%, respectively. Serum CA19-9 and CEA concentrations were significantly elevated (P<0.001 and P<0.05) in patients with cholangiocarcinoma (290.31+/-5.34 KU/L(-1) and 36.46+/-18.03 microg/L(-1)) compared with patients with benign biliary diseases (13.38+/-2.59 KU/L(-1) and 13.84+/-3.85 microg/L(-1)) and healthy individuals (12.78+/-3.69 KU/L(-1) and 11.48+/-3.37 microg/L(-1)). In 15 patients undergoing curative resection of cholangiocarcinoma, the mean serum CA19-9 concentration was decreased from a preoperative level of 286.41+/-4.36 KU/L(-1) to a postoperative level of 62.01+/-17.43 KU/L(-1) (P<0.001), and the mean serum CEA concentration from 39.41+/-24.35 microg/L(-1) to 28.69+/-11.03 microg/L(-1) (P<0.05). In patients with cholangiocarcinoma, however, no correlation was found between serum CEA and CA19-9 concentrations (r=0.036). CONCLUSION: These data suggest that the serum CA19-9 determination is a useful addition to the available tests for the differential diagnosis of cholangiocarcinoma. Serum CA19-9 is an effective tumor marker in diagnosing cholangiocarcinoma, deciding whether the tumor has been radically resected and monitoring effect of treatment.