Favorable disease-free survival associated with programmed death ligand 1 expression in patients with surgically resected small-cell lung cancer

Background: The prognostic significance of programmed death ligand 1 (PD-L1) has been reported in non-small cell lung cancer; however, the significance of PDL1 expression in patients with resected small-cell lung cancer (SCLC) remains to be clarified. Materials and Methods: Forty patients with SCLC whose resected specimens were available for immunohistochemistry for PDL1 were evaluated to determine the association between its expression and the clinicopathological factors and prognosis. Results: Among 40 patients, PD-L1 was expressed in tumor cells (TCs) of six (15%), tumor-infiltrating cells (ICs) of 16 (40%), and TCs and/or ICs cells of 18 (45%) patients. Patients with PD-L1-positve ICs and TCs and/or ICs exhibited significantly longer disease-free survival than those without PD-L1-expression (hazard ratio (HR)=0.268; 95% confidence interval (CI)=0.100-0.645; p=0.003 and HR=0.301; 95% CI=0.118-0.702; p=0.005, respectively). Conclusion: This study provides important evidence on the prognostic value of the PD-L1 expression in resected SCLC patients.