The Impact of Programmed Death-Ligand 1 Expression on the Prognosis of Early Stage Resected Non-Small Cell Lung Cancer: A Meta-Analysis of Literatures

INTRODUCTION: Previous studies have demonstrated that programmed cell death-ligand 1 (PD-L1) serves as biomarker for poor prognosis and survival in advanced-stage non-small cell lung cancer (NSCLC) patients. However, the merit of PD-L1 expression to predict the prognosis of early stage NSCLC patients who underwent complete resection remains controversial. In the present study, we performed a meta-analysis to investigate the relationship between PD-L1 expression and prognosis in patients with early stage resected NSCLC. METHODS: Electronic databases, including PubMed, EMBASE, and the Cochrane Library, were searched until July 23 2020 for studies evaluating the expression of PD-L1 and the prognosis of resected NSCLCs. Hazard ratios (HRs) with 95% confidence intervals (CIs) of overall survival (OS) and disease-free survival (DFS) were pooled and analyzed. Heterogeneity and publication bias analyses were also assessed. RESULTS: A total of 15 studies involving 3,790 patients were considered in the present meta-analysis. The pooled HR indicated that PD-L1 expression related to a much shorter DFS (HR = 1.56, 95% CI: 1.18–2.05, p < 0.01), as well a significantly worse OS (HR = 1.68, 95% CI: 1.29–2.18, p < 0.01). Furthermore, our analysis indicated that PD-L1 expression was significantly associated with gender (male vs. female: OR = 1.27, 95% CI:1.01–1.59, p = 0.038), histology (ADC vs. SCC: OR = 0.54, 95% CI:0.38–0.77, p = 0.001), TNM stage (I vs. II–III: OR = 0.45, 95% CI:0.34–0.60, p = 0.000), smoking status (Yes vs No: OR = 1.43, 95% CI:1.14–1.80, p = 0.002) and lymph node metastasis (N+ vs N−: OR = 1.97, 95% CI:1.26–3.08, p = 0.003). CONCLUSIONS: The results of this meta-analysis suggest that PD-L1 expression predicts an unfavorable prognosis in early stage resected NSCLCs. The role of personalized anti-PD-L1/PD-1 immunotherapy in the adjuvant settings of resected NSCLC warrants further investigation.