Article Abstract

The clinicopathological and prognostic significance of PD-L1 expression assessed by immunohistochemistry in lung cancer: a meta-analysis of 50 studies with 11,383 patients

Authors: Huijuan Li, Yangyang Xu, Bing Wan, Yong Song, Ping Zhan, Yangbo Hu, Qun Zhang, Fang Zhang, Hongbing Liu, Tianhong Li, Haruhiko Sugimura, Federico Cappuzzo, Dang Lin, Tangfeng Lv, written on behalf of AME Lung Cancer Collaborative Group


Background: We conducted a meta-analysis to systematically evaluate the relationship between programmed death-ligand 1 (PD-L1) expression and survival in patients with lung cancer.
Methods: The electronic databases PubMed, Embase, Cochrane, and Web of Science were searched up to January 2nd, 2018, for articles relating to PD-L1 expression detected by immunohistochemistry (IHC) and lung cancer patient prognosis.
Results: Fifty studies including 11,383 patients published between 2011 and 2017 were enrolled in this meta-analysis. The pooled hazard ratios (HRs) and 95% confidence intervals (CIs) suggested that PDL1 IHC expression was related to poor overall survival (OS) (HR =1.45, 95% CI: 1.24–1.68). In subgroup analysis categorized according to sample type, cut-off value, ethnicity and TNM stage, the pooled results demonstrated inferior survival in the PD-L1 positive group when the PD-L1 expression was detected by resection specimens (P=0.000), 5% was taken as the cutoff value (P=0.000), the patients were in early stage (I–III) (P=0.000), and the geographic setting of the study was in Asia (P=0.000). Besides, patients with high PDL1 expression had shorter OS in NSCLC (P=0.000), ADC (P=0.000), SCC (P=0.353) and LELC (P=0.810), while no significant difference was observed in SCLC (P=0.000). The pooled odds ratios (ORs) suggested that PD-L1 expression was associated with male (P<0.001), smoker (P<0.001), poor tumor differentiation (P=0.014), large tumor size (P=0.132), positive lymph nodal metastasis (P=0.002), EGFR wild-type status (P<0.001) and KRAS mutations (P=0.393). However, age (P=0.15) and ALK rearrangements (P=0.567) had no bearing on PD-L1 expression.
Conclusions: PD-L1 expression that is associated with several clinicopathological feactures may serve as a poor prognostic biomarker for patients with lung cancer.