Clinical Significance of Programmed Death Ligand-1 Expression in Esophageal Squamous Cell Carcinoma

Background: The aim of this study was to evaluate the association between the expression of programmed death ligand-1 (PD-L1) and clinical outcomes in patients with surgically resected esophageal squamous cell carcinoma (ESCC). Materials and methods: We included 76 patients with primary ESCC who underwent surgical resection between January 2009 and December 2014 at National Defense Medical College Hospital. Using the tumor tissues, we evaluated PD-L1 expression in tumor cells and stromal reactive lymphocytes via immunohistochemistry. Furthermore, the relationship between PD-L1 expression and the clinicopathological status of patients with ESCC was investigated. Results: PD-L1 expression in tumor cells was detected in 39.5% of the patients. In addition, 51.3% of the patients had PD-L1-positive stromal reactive lymphocytes and exhibited significantly longer overall survival than those with lack of PD-L1 expression in stromal reactive lymphocytes (median survival time, 56.0 versus 27.3 mo; log-rank test, P = 0.04). Patients with lack of PD-L1 expression in both tumor cells and stromal reactive lymphocytes showed worse overall survival than those with the PD-L1-positive expression in tumor cells and/or stromal reactive lymphocytes (P = 0.02). Conclusions: PD-L1-positive expression in stromal reactive lymphocytes, rather than in tumor cells, is associated with a longer survival in patients with ESCC. (C) 2020 Published by Elsevier Inc.