The relationship between clinicopathological parameters and PD-L1 expression level in advanced stage non-small cell lung cancer.

Introduction: Clinicopathological parameters related to programmed death ligand 1 (PD-L1) expression levels have been investigated in several studies. However, the results of these studies are conflicting and vary in different populations. This study aimed to investigate the relation of clinicopathological parameters with PD-L1 expression level in advanced stage non-small cell lung cancer patients. Materials and Methods: The patients diagnosed with non-small cell lung cancer were enrolled, retrospectively. The data of clinicopathological parameters was collected. Clinicopathological parameters in relation to PD-L1 expression levels (0%, 1-50%, and >50%) were analyzed as univariable and multivariable. Result: In total, 384 patients were enrolled. PD-L1 expression in tumor cells was between 1-50%, and >50% in 41.4%, and 23.4% of patients, respectively. There was no PD-L1 expression in 35.2% of the patients. In univariable analysis, we found that the parameters associated with PD-L1 expression levels revealed that metastatic site number, the subtype of cancer, diagnostic material type, platelet number, and LDH level were statistically significant. Adenocarcinoma frequency was higher in tumors that had PD-L1 expression >50% than in tumors that did not express PD-L1 and the difference was statistically significant (p= 0.04, coefficient= 0.3, 95% CI 0.09-0.94). Cytology as diagnostic material was significant in PD-L1 level 1-50% comparing to >50% (p= 0.02, coefficient= 2.2, 95% CI= 1.08-4.46). Conclusions: According to the results of our study, many of the clinicopathological parameters are not related to the PD-L1 level. The histological subtype and diagnostic material may affect the level of PD-L1 expression.