Background
Programmed death-ligand 1 (PD-L1) is an immune checkpoint molecule expressed by cancer cells. Previous studies have demonstrated the prognostic role of PD-L1 expression in patients with small cell lung cancer (SCLC), where the
Conclusions
This meta-analysis suggests that PD-L1 expression is not a significant prognostic factor of poor survival in SCLC. Because of significant variations, high-quality studies are needed to validate our results.
Methods
We searched the PubMed, Embase, ISI Web of Science, and Cochrane Library databases for articles published before and on March 2nd, 2020. Data of PD-L1 expression in tumor cells detected using immunohistochemistry methods were extracted for analysis. Pooled hazard ratios (HRs) with confidence intervals (CIs) and odds ratios (ORs) with 95% CIs were calculated to assess the correlations among PD-L1, overall survival (OS), and clinicopathological factors.
Results
Nine studies of 921 patients published between 2015 and 2019 were included in this meta-analysis. The pooled data (HR = 0.91, 95% CI = 0.46-1.80, p = 0.787) indicated that PD-L1 expression is not a significant predictor of poor OS. Moreover, the results also revealed that PD-L1 expression is not significantly associated with gender (OR = 1.12, 95% CI = 0.73-1.74, p = 0.601), age (OR = 1.15, 95% CI = 0.58-2.30, p = 0.683), pN stage (OR = 0.65, 95% CI = 0.24-1.72, p = 0.381), pT stage (OR = 1.16, 95% CI = 0.26-5.23, p = 0.847), serum lactate dehydrogenase level (OR = 1.06, 95% CI = 0.13-8.43, p = 0.958), or performance status (OR = 0.69, 95% CI = 0.24-1.95, p = 0.479). No significant publication bias was detected in this meta-analysis. Conclusions: This meta-analysis suggests that PD-L1 expression is not a significant prognostic factor of poor survival in SCLC. Because of significant variations, high-quality studies are needed to validate our results.