Multi-omics Monitoring of Dynamic Evolution in Esophageal Squamous Cell Carcinoma: PKU-ESCC-Monitor

Inclusion Criteria: Peri-operative cohort: 1. Age ≥18 and \<80 years; ECOG 0-1. 2. Histologically confirmed ESCC. 3. Completed standard neoadjuvant therapy and planned/underwent 4.transthoracic esophagectomy with routine surgical specimens available. 5.Able to provide clinical course/outcomes and comply with follow-up at participating sites. Advanced first-line immunotherapy cohort: 1. Age ≥18 and \<80 years; ECOG 0-1. 2. Histologically confirmed ESCC, or highly suspected by endoscopy/imaging when surgery is not feasible. 3. No prior systemic anti-cancer therapy for advanced disease; archived FFPE slides (3-5 µm, 5-8 slides) acceptable if fresh tissue unavailable. 4. Able to provide clinical information and comply with follow-up. Exclusion Criteria: 1. Prior anti-cancer therapy (except standard neoadjuvant therapy in the peri-operative cohort). 2. Other malignancy within 5 years (exceptions: non-melanoma skin cancer, in-situ melanoma, in-situ cervical cancer). 3. Inadequate clinical information. 4. Known infection with HIV, HBV, HCV, or syphilis. 5. Pre-operative imaging indicates insufficient tumor tissue (no visible target region) for study procedures. 6. Any condition deemed by investigators to make the patient unsuitable.