PD-L1 expression and its clinicopathological correlation in advanced esophageal squamous cell carcinoma in a Chinese population

Background Programmed death ligand 1 (PD-L1) is a ligand for the inhibitory programmed cell death protein 1 (PD-1), which are targeted by several anti-PD-1 and PD-L1 drugs for a variety of human cancers. However, only a few studies have evaluated PD-L1 expression in esophageal squamous cell carcinoma (ESCC) with a large Chinese cohort. Our present study is to evaluate the association of PD-L1 expression with clinicopathological features on ESCC. Methods Using tissue microarray and immunohistochemistry, PD-L1 expression on tumor cells and tumor-infiltrating immune cells was studied in 378 advanced ESCC patients without neoadjuvant chemoradiotherapy. Its correlation with clinicopathological parameters was analyzed. Results PD-L1 was expressed on 29.9% (113/378) ESCC tumor cells and 40.2% (152/378) tumor-infiltrating immune cells. PD-L1 expression in tumor cells was significantly correlated with age, degree of differentiation, T stage, N stage and metachronous hematogenous metastasis, and PD-L1 expression in tumor-infiltrating immune cells was significantly associated with N stage (P