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Forest plot showing the association between programmed death ligand-1 (PD-L1) expression status with disease-free survival (DFS). (A) All 12 eligible studies (11 publications) for DFS. (B) Subgrouped by country (Asia/non-Asia). (C) 11 eligible studies (10 publications) for DFS in esophageal squamous cell carcinoma (ESCC).
