Different role of MSLN and CA125 co-expression as a prognostic predictor between perihilar and distal bile duct carcinoma

Recent studies have suggested that the interaction of mesothelin (MSLN) and cancer antigen 125 (CA125) enhances tumor metastases. The aim of the present study was to clarify the impact of MSLN and CA125 co-expression on the prognosis of patients with extrahepatic bile duct carcinoma (BDC). Tissue samples from patients who underwent surgical resection between 2007 and 2015 for perihilar or distal BDC were immunohistochemically examined. The expression levels of MSLN and CA125 in tumor cells were analyzed. The expression in <50% and ≥50% of the total tumor cells were defined as low- and high-level expression, respectively. Tissue samples were obtained from 31 patients with perihilar BDC and 43 patients with distal BDC. Lymph node metastases were associated with MSLN and CA125 co-expression in patients with perihilar BDC (P=0.002), while there was no association between lymph node metastasis and co-expression in patients with distal BDC (P=0.362). MSLN and CA125 co-expression was associated with a worse overall survival rate in patients with perihilar BDC (5-year overall survival rate, co-expression positive vs. negative, 24 vs. 63%; P=0.038). To the best of our knowledge, the present study is the first to report an association between co-expression of MSLN and CA125 with a poor prognosis in patients with perihilar BDC. The current findings suggested that the significance of co-expression differed according to the BDC location.