It is reported that compared to chemotherapy alone, immunochemotherapy has significantly improved the overall survival of patients with advanced metastatic ESCC. However, there are still more than 30% of patients who cannot benefit from this treatment modality. In addition to these factors, the time-of-day infusion and administration sequence of immunochemotherapy have been reported to be associated with tumor responses and overall survival. In this study, The investigators aimed to explore the roles of infusion time and administration sequence of immunochemotherapy in predicting tumor responses and overall survival in patients with advanced ESCC.

Inclusion Criteria:

• Pathologically diagnosed as esophageal squamous cell carcinoma
• KPS≥80
• Adequate organ function
• No distant metastasis
• The diseases could be resected or potentially resectable after immunochemotherapy assessed by a thoracic oncologist

Exclusion Criteria:

• incomplete medical record which affects statistical analysis
• have participated in previous interventional clinical trials
• other situations evaluated by investigators not meet the enrollment

Patients diagnosed as potentially resectable (including initially-unresectable) esophageal squamous cell carcinoma via pathological specimen, KPS ≥ 80, has adequate organ function and no distant metastasis are included in the study