PD-L1 expression on tumor cells associated with favorable prognosis in surgically resected esophageal squamous cell carcinoma.

There is limited evidence regarding the relationship between programmed cell death ligand 1 (PD-L1) expression on tumor cells (TCs) and prognosis of esophageal squamous cell carcinoma (ESCC). This retrospective study aimed to investigate the clinical significance of PD-L1 expression in ESCC. To assess PD-L1 expression, we conducted immunohistochemistry studies using a tissue microarray encompassing 233 ESCC cases, stages I, II, and III, with detailed clinical data. PD-L1 expression on TCs was observed in 55.4% (129/233) of ESCC cases and was not associated with clinicopathological factors. ESCC patients with PD-L1-positive tumors showed significantly better overall survival and disease-free survival than did those with PD-L1-negative tumors (P = .023 and P = .026, respectively). When patients were stratified into those with stage I-II (127; 54.5%) and stage III (106; 45.5%) disease and those without (134; 57.5%) and with (99; 42.5%) lymph node metastasis, the prognostic effect was inconsistent. The overall survival and disease-free survival of patients with positive PD-L1 expression were significantly better in patients with stage I-II disease (P = .021 and P = .015, respectively) and without lymph node metastasis (P = .009 and P = .07, respectively) than their counterparts. Our results showed that PD-L1 expression on TCs was an independent predictor of prognosis of ESCC patients. However, the effect varied in patients with different stages and lymph node status. Positive PD-L1 expression was a favorable predictor in ESCC patients with stage I-II disease or without lymph node metastasis but not in patients with stage III disease or lymph node metastasis.