Clinical significance of PD-L1 expression in patients with surgically resected non-small cell lung cancer.

Abstract

To explore the expression of programmed death ligand-1 (PD-L1) as well as the correlation between the expression and the clinicopathological features or prognosis in non-small cell lung cancer (NSCLC). The expression of PD-L1 protein in 254 cases of surgically resected lung adenocarcinoma (L-ADC), 228 cases of surgically resected lung squamous cell cancer (L-SCC), and 99 cases of non-cancerous control lung tissues was detected with immunohistochemical SP method. The correlation between the PD-L1 expression and clinicopathological features was analyzed. Kaplan-Meier univariate and Cox multivariate regression analyses were performed to assess the prognosis of patients with L-ADC and L-SCC, respectively. Positive percentage of PD-L1 protein expression was higher in the tissues of L-ADC and L-SCC than that in the non-cancerous control lung tissues respectively (both P<0.05). Positive percentage of PD-L1 protein expression was higher in the tissues of L-SCC than that in the tissues of L-ADC (P<0.05). However, there were no correlation between the expression of PD-L1 and age, gender, pathological grades, clinical stages, and lymph node metastasis in L-ADC and L-SCC respectively (all P>0.05). Overall survival rate was evidently lower in the L-ADC patients with positive expression of PD-L1 protein compared to the patients with negative staining of PD-L1 (P<0.01). Multivariate Cox regression analysis further identified that the L-ADC patients of positive expression of PD-L1 protein had a poor prognosis (P<0.01). The positive percentage of PD-L1 protein expression is higher in the L-SCC patients than that in the L-ADC patients. Positive expression of PD-L1 protein can be served as an independent prognostic factor of poor prognosis in the patients with L-ADC.