Assessment of bile and serum mucin5AC in cholangiocarcinoma: diagnostic performance and biologic significance.

BACKGROUND: Recent studies have showed the efficacy of mucin5AC (MUC5AC) as a diagnostic and prognostic serum biomarker in biliary tract tumors. The aim of the present investigation was to improve the current knowledge on the biologic relevance of MUC5AC in malignant and benign biliary disorders by comparing its diagnostic performance in both bile and serum samples of patients with cholangiocarcinoma (CCA) or benign biliary disorders. METHODS: A quantitative determination of MUC5AC by enzyme-linked immunosorbent assay was performed in bile and serum specimens from 26 patients with extrahepatic CCA and 20 subjects with benign biliary disorders (10 with biliary stones and 10 with cholangitis). Verification analysis was made by immunoblot. RESULTS: MUC5AC of serum and biliary origin contributed to different extent to total levels of MUC5AC in the different groups of patients. In particular, the transition toward a greater degree of injury of bile duct epithelium was accompanied by a greater amount of MUC5AC in serum than in bile. The diagnostic performance of MUC5AC expressed as serum/bile ratio showed excellent diagnostic performance for differentiating CCA from cholangitis (area under the curve [AUC], 0.94; 95% CI, 0.86-1.00; P < .0001), CCA from biliary stones (AUC, 0.99; 95% CI, 0.98-1.00; P < .0001), as well as cholangitis from biliary stones (AUC, 0.93; 95% CI, 0.82-1.00; P = .001). CONCLUSION: These findings provide new insight into the biologic importance of MUC5AC in biliary disorders and suggest that combined assessment of MUC5AC in bile and serum with expression of data in terms of serum to bile ratio may improve the diagnostic performance of MUC5AC quantification in serum alone.