Programmed death-ligand 1 positivity can predict improved survival and a lower risk of brain metastasis in patients with resectable small cell lung cancer

The present study aimed to investigate the expression of programmed death-ligand 1 (PD-L1) in resectable small cell lung cancer (SCLC) and investigate its predictive value for survival and brain metastasis (BM). Postoperative SCLC specimens were immunostained with the SP142 antibody against PD-L1. Positive PD-L1 expression was defined as PD-L1 expression in ≥5% of tumor cells. A total of 80 patients were recruited between January 2010 and December 2012. PD-L1 was expressed in 65.0% (52/80) of all patients and 59.3% (16/27) of patients with BM. The median survival time (MST) was longer in the PD-L1(+) group (46.4 vs. 28.5 months, P=0.002). There was no significant difference in the MST between patients with PD-L1(+) or (−) BM (P=0.55). The 3-year risk of BM in the PD-L1(+) group was lower than that in the PD-L1(−) group (24.1 vs. 48.4%, P=0.046). PD-L1 was an independent factor for overall survival (OS) [hazard ratio (HR)=0.485, P=0.011] and BM (HR=0.335, P=0.024). The present study concludes that PD-L1 is commonly expressed in SCLC and is associated with OS and BM.