BackgroundLung cancer is one of the most lethal cancers worldwide, but studies have shown that the higher the expression of programmed cell death protein 1 ligand 1 (PD-L1) in non-small cell lung cancer (NSCLC), the more likely it will benefit from anti-PD-L1 immunotherapy. The purpose of our study was to collect and analyze abundant clinical samples in order to provide evidence for clinicians and patients who might consider anti-PD-L1 immunotherapy while jointly formulating treatment plans.MethodsOn the one hand, we obtained cases from The Cancer Genome Atlas (TCGA) database, including 498 lung squamous cell cancer (LUSC) patients and 515 lung adenocarcinoma (LUAD) patients. We studied the lung caner driver gene in LUSC and LUAD. On the other hand, PD-L1 expression was detected in lung cancer tissues of 1,008 NSCLC patients with immunohistochemistry staining (IHC), and we studied the correlation between PD-L1 protein expression and clinicopathological characteristics.ResultsPD-L1 expression was higher in LUSC than in LUAD at the mRNA level. In univariate analysis, PD-L1 expression at the protein level was higher in patients who were males, were LUSC, were smokers, had a tumor diameter >3 cm, had poor differentiation, or had stages III~IV disease. In multivariate analysis, PD-L1 expression was higher in patients who were LUSC or in poor differentiation.ConclusionIn term of protein level, PD-L1 expression was higher in NSCLC patients who were LUSC or in poor differentiation. We recommend that PD-L1 IHC detection can be routinely performed in such populations that are likely to benefit most from PD-L1 immunotherapy.