CD9 and mesothelioma: Mesothelioma patients with a younger age (P=0.0083), epithelioid histology (P<0.0001), differentiated type EMs (P=0.0027), who did not receive best supportive care (P=0.0469), who underwent EPP and chemotherapy (P=0.0195) and who received chemotherapy with inclusion of pemetrexed (P=0.0434) showed statistically significantly a high frequency of positive CD9 expression.