Co-Expression of Mesothelin and CA125 Is Associated with the Poor Prognosis of Endometrial Serous Carcinoma and Mixed Carcinomas Including Serous Carcinoma

The aim of this study was to investigate the association between the clinicopathologic factors and either expression or co-expression of mesothelin and cancer antigen (CA) 125 in endometrial serous carcinoma and mixed carcinomas including serous carcinoma. Between 1990 and 2017, patients with endometrial serous carcinoma and mixed carcinoma including serous carcinoma treated by total hysterectomy and bilateral salpingo-oophorectomy at our hospital were identified. The association between either expression or co-expression of mesothelin and CA125 was evaluated by immunochemical analysis and the clinico-pathological features were retrospectively examined. Among the 40 patients included, 19, 31, and 18 patients exhibited single positive mesothelin, single positive CA125, and positive co-expression, respectively. The expression of mesothelin and CA125 was observed to be positively associated (p = 0.021). There was no significant association of age and FIGO stage with individual mesothelin or CA125 expression or their co-expression. Overall survival (OS), but not progression-free survivals (PFS), of only mesothelin-positive patients was worse (p = 0.024). Hence, OS and PFS of patients with positive co-expression were worse (PFS:p = 0.043, OS:p = 0.012). In multivariate analysis, single mesothelin expression and single CA125 expression did not lead to worse prognosis. However, positive co-expression was the worst prognostic factor for OS (hazard ratio: 3.32,p = 0.039). Co-expression of mesothelin and CA125 may accurately predict OS in endometrial serous carcinoma and mixed carcinomas including serous carcinoma. Further studies should examine this relationship.