Overexpression of Programmed Cell Death-Ligand 1 in Small-Cell Lung Cancer and Survival Analysis

Abstract

Purpose: Programmed cell death-ligand-1 (PD-L1) has identified overexpression in many solid carcinomas. However, the expression in small cell lung cancer (SCLC) remains unclear and the association between the PD-L1 expression and prognosis is not well investigated. Methods: The expression of PD-L1 was evaluated in 136 specimens of SCLC by immunohistochemistry in Huai’an First People’s Hospital. PD-L1 expression was defined as tumors staining in over 5% of tumor cells. Survival analysis was evaluated using the Kaplan-Meier method. Multivariate regression was performed with the Cox proportional hazards model. Results: One hundred and thirty-six patients were enrolled in present study,including 78 of extensive and 58 with limited stage. PD-L1 expression was detected in 54.4% of all the patients (53.8% in extensive and 55.2% in limited stage). Patients with PD-L1 positive expression showed better overall survival (OS) than PD-L1 negative patients regardless of extensive or limited small cell lung cancer (P value were 0.002 and 0.016, respectively). One hundred and twenty-one patients were with recurrence or metastasis. Median progression free survival of first-line chemotherapy in PD-L1 positive patients was 5.30 and 3.50 months in PD-L1 negative patients (P=0.030). PD-L1 remained as significant prognostic factor for better survival with multivariate analyses (HR=0.76; P=0.041). Conclusion: Our results that PD-L1 is overexpressed in 54.4% of SCLC patients. Expression of PD-L1 is correlated with a favorable PFS and OS in SCLC.