Amount of Epithelioid Differentiation Is a Predictor of Survival in Malignant Pleural Mesothelioma

Abstract

Background Macroscopic complete surgical resection with adjuvant chemotherapy can provide a survival advantage in patients with malignant pleural mesothelioma (MPM). Patients with nonepithelioid histology are largely excluded from such radical operations even though they might benefit. The degree of epithelioid differentiation varies in biphasic histology. We report the outcomes of pleurectomy and decortication and the effect of epithelioid differentiation on overall survival of patients with MPM. Methods This report is based on the outcomes of 144 patients who underwent pleurectomy and decortication at a single institution between 2008 and 2015. The variables assessed were age, gender, histology, and pathologic T and N stage. No patients with pure sarcomatoid histology were included. Two independent pathologists estimated the percentage of epithelioid histology. A Cox regression model was used to identify significant predictors of survival. The Kaplan-Meier method was used to summarize overall and subgroup survival. Results Included were 116 men and 28 women with a median age of 69 years (range, 43 to 88 years). The 2-year survival from pleurectomy and decortication was 20%. Median survival overall was 13.34 months and was 20.1 months for the 100% epithelioid subgroup (n = 77), 11.8 months for the 51% to 99% epithelioid subgroup (n = 39), and 6.62 months for the less than 50% epithelioid subgroup (n = 28). The amount of epithelioid differentiation was a significant predictor of survival (p < 0.001). Differences in survival based on the T, but N stage, were not statistically significant. Conclusions The percentage of epithelioid differentiation is an independent predictor of survival in MPM and should be taken into careful consideration when recommending surgical treatment for patients with biphasic MPM.