Abstract
BACKGROUND: PD-L1 expression in tumor cells has been associated with the efficacy of immune checkpoint inhibitors in non-small cell lung cancer (NSCLC). The aim of this study was to explore correlations between smoking, genetic profiles, patient outcomes, and PD-L1 expression in NSCLC. METHODS: PD-L1 expression was evaluated in 241 surgically resected specimens by immunostaining and 50% was set as the cutoff value. RESULTS: Of the 241 tumors analyzed, a PD-L1 tumor proportion score (TPS) of ≥ 50% was detected in 35 cases (14.5%) and a TPS of < 50% in 206 cases (85.5%). A PD-L1 TPS ≥ 50% was significantly associated with smoking and EGFR wild-type status (P < 0.001 and P = 0.039, respectively). Detailed assessment of smoking variables showed that total smoking duration was a predictor of a PD-L1 TPS ≥ 50% (P = 0.001). Univariate and multivariate survival analyses revealed that patients with a PD-L1 TPS ≥ 50% had poorer disease-free and overall survival than those with a PD-L1 TPS < 50% (P = 0.001 and P < 0.001, respectively). CONCLUSION: The incidence of a PD-L1 TPS ≥ 50% was significantly higher in smoking and EGFR wild-type NSCLC patients, particularly in long-term smokers. A PD-L1 TPS of ≥ 50% was an independent adverse prognostic factor for survival in patients with NSCLC.