Fig. 4From: PD-1 inhibitors versus chemotherapy as second-line treatment for advanced esophageal squamous cell carcinoma: a meta-analysisForest plots of HR for OS in the patients with either positive or negative PD-L1 expression assigned to the PD-1 inhibitor group, compared with those in the chemotherapy group. Abbreviations. HR: hazard ratio; OS: overall survivalBack to article page