Currently in network meta-analyses, only cost-effectiveness analyses of PD-1 inhibitors as second-line treatment for advanced squamous esophageal cancer have been performed (25, 26), however, no consensus has been reached on the optimal choice of PD-1 inhibitors for second-line treatment of patients with advanced ESCC in terms of efficacy and safety. This evidence concerns the gene PDCD1 and esophageal squamous cell carcinoma.