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

Abstract

<div class="section"> <a class="named-anchor" id="d6230819e444"> <!-- named anchor --> </a> <h5 class="section-title" id="d6230819e445">Background</h5> <p id="d6230819e447">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. </p> </div><div class="section"> <a class="named-anchor" id="d6230819e449"> <!-- named anchor --> </a> <h5 class="section-title" id="d6230819e450">Methods</h5> <p id="d6230819e452">The electronic databases PubMed, Embase, Cochrane, and Web of Science were searched up to January 2 ^nd, 2018, for articles relating to PD-L1 expression detected by immunohistochemistry (IHC) and lung cancer patient prognosis. </p> </div><div class="section"> <a class="named-anchor" id="d6230819e457"> <!-- named anchor --> </a> <h5 class="section-title" id="d6230819e458">Results</h5> <p id="d6230819e460">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 PD-L1 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 PD-L1 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&lt;0.001), smoker (P&lt;0.001), poor tumor differentiation (P=0.014), large tumor size (P=0.132), positive lymph nodal metastasis (P=0.002), <i>EGFR</i> wild-type status (P&lt;0.001) and <i>KRAS</i> mutations (P=0.393). However, age (P=0.15) and <i>ALK</i> rearrangements (P=0.567) had no bearing on PD-L1 expression. </p> </div><div class="section"> <a class="named-anchor" id="d6230819e471"> <!-- named anchor --> </a> <h5 class="section-title" id="d6230819e472">Conclusions</h5> <p id="d6230819e474">PD-L1 expression that is associated with several clinicopathological feactures may serve as a poor prognostic biomarker for patients with lung cancer. </p> </div>