Prognostic impact of PD-L1 expression in correlation with neutrophil-to-lymphocyte ratio in squamous cell carcinoma of the lung

The prognostic impact of tumoral programmed death-ligand 1 (PD-L1) expression in correlation with neutrophil-to-lymphocyte ratio (NLR) was retrospectively assessed in 83 patients with completely resected stage I squamous cell carcinoma of the lung, as PD-L1 is a potent regulator of cancer immunity and NLR is a potential surrogate of immune status. Forty-three patients (51.8%) had tumor with positive PD-L1 expression. There was no significant correlation between PD-L1 expression and NLR. PD-L1-positivity failed to provide a significant prognostic impact (overall survival [OS] rate at 5 years, 53.0% in PD-L1-positive patients versus 70.1% in PD-L1-negative patients; P = 0.117). Among NLR-low (<2.2) patients, however, PD-L1-positivity was significantly correlated with a poor prognosis (OS rate at 5 years, 46.1% versus 86.0%; P = 0.020). In contrast, among NLR-high (≥2.2) patients, PD-L1-positivity provided no prognostic impact (P = 0.680). When NLR status and tumoral PD-L1 status were combined, “NLR-low and PD-L1-negative” was a significant and independent factor to predict a favorable recurrence-free survival (hazard ratio, 0.237 [95% confidence interval, 0.083 to 0.674]; P = 0.007) and OS (hazard ratio, 0.260 [0.091 to 0.745]; P = 0.012). These results suggest the prognostic impact of tumoral PD-L1 expression might be influenced by the status of NLR.