Mesothelin expression is a prognostic factor in cholangiocellular carcinoma

Although mesothelin is highly expressed in epithelial mesotheliomas, and also in adenocarcinomas of the ovary and pancreas, the clinical significance of mesothelin in cholangiocellular carcinoma (CC) has not been reported, and its biologic features are largely unknown. In the present study, mesothelin expression was evaluated in 25 patients with CC using a well-characterized mesothelin monoclonal antibody (5B2). A total of 8 of the 25 patients with CC (32%) showed mesothelin immunoreactivity. The 25 patients were divided into 2 groups according to the percentage of tumor cells that were positive for mesothelin expression: negative (n = 17) or focally positive (mesothelin expression evident in less than 50%, n = 4; total, n = 21 for both groups), and positive (mesothelin expression evident in 50% or more, n = 4). The survival periods in both groups were statistically analyzed. The negative/focally positive group showed significantly longer postoperative survival than the positive group (P = 0.006). Also, mesothelin positivity was identified as an independent predictor of short postoperative survival. The present results suggest that mesothelin expression is a prognostic indicator in patients with CC.