Prognostic significance of programmed death-1 and programmed death-ligand 1 expression in patients with esophageal squamous cell carcinoma

AIMS To evaluate the expression of programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) and their clinical and prognostic significance in primary esophageal squamous cell carcinoma (ESCC). RESULTS The expression rate of PD-1 and PD-L1 in ESCC was 33.5% (117/349) and 41.4% (222/536), respectively. PD-L1 expression differed significantly by tumor location, grade, lymph node metastases, and disease stage (P < 0.05). Moreover, its expression was associated with the disease free survival (DFS). Patients with positive PD-L1 expression had reduced risk for disease relapse compared to those without PD-L1 expression (Hazard ratio [HR] = 0.75, 95% confidence interval [CI]: 0.56-1.00, P = 0.048). Kaplan-Meier curves showed the similar result, P = 0.047. However, there was no significant correlation between PD-1 expression and clinicopathological factors or outcome in ESCC (P > 0.05). METHODS The expression of PD-1 and PD-L1 was assessed by immunohistochemistry on tissue microarrays from 536 primary ESCC who underwent surgery during January 2008 and April 2012 in Zhejiang Cancer Hospital. Chi-square test and Cox proportional hazards regression were employed to analyze the associations between their expressions and clinicopathological variables and survival. CONCLUSIONS Our results suggested that PD-L1 could be a favorable indicator of prognosis in ESCC.