Mesothelin expression and its prognostic role according to microsatellite instability status in colorectal adenocarcinoma

Abstract

The cell-surface glycoprotein, mesothelin, is normally present on mesothelial cells. Overexpression of mesothelin has been reported in many tumors and is correlated with poor outcome. We investigated the clinicopathologic significance of mesothelin expression in colorectal adenocarcinoma with microsatellites instability (MSI) status. Mesothelin expression was evaluated immunohistochemically in tissue microarray blocks from 390 colorectal adenocarcinoma samples. Mesothelin expression was interpreted according to the intensity and extent. A score of 2 was considered high expression. We analyzed the correlation between mesothelin expression and clinicopathologic characteristics. Highmesothelinexpressionwasobservedin177(45.4%)out of390colorectaladenocarcinomasamplesandwassignificantlyassociated with high histologic grade (P=.037), lymphatic invasion (P=.028), lymph node metastasis (P=.028), and high AJCC stage (P=.026). Kaplan–Meier survival curves revealed no significant difference between patients with high mesothelin expression and patients with low mesothelin expression in both recurrence-free survival (RFS) and cancer-specific survival (P=.609 and P=.167, respectively). In subgroup survival analyses,highmesothelin expressionwasassociatedwith poorRFSintheMSI-Highgroupofcolorectaladenocarcinoma (P=.004). High mesothelin expression was significantly associated with aggressive phenotypes and poor patient outcome in MSI-High colorectal adenocarcinoma.