PD-1 Inhibitors Combined With Local Therapy at Different Timings in Oligometastatic ESCC

Inclusion Criteria: 1. An eastern cooperative oncology group (ECOG) score of 0-1. 2. Histologically or cytologically confirmed diagnosis of esophageal squamous cell carcinoma. 3. Genuine oligometastasis (without a history of polyme-tastatic disease). 4. A total of four or fewer distant metastases, a maximum of three metastases in a single organ, and a maximum diameter of each metastatic lesion not exceeding 5 cm. 5. Biopsy of a metastatic lesion, PET/CT scan, and PD-L1 CPS (IHC 22C3) are not required but preferred. 6. No history of anti-PD-1/PD-L1 therapy. However, the following conditions are also eligible for inclusion: the use of anti-PD1/PD-L1 during induction/neoadjuvant/ concurrent therapy, or the use of anti-PD1/PD-L1 for maintenance therapy but not due to toxicity or disease progression interrupting anti-PD1/PD-L1 treatment, and the interruption has lasted for more than 3 months. 7. Adequate hematological, hepatic, renal, and coagula-tion function. Baseline laboratory tests required to assess eligibility, including ANC ≥ 1.5 × 10\^9/L, PLT ≥ 80 × 10\^9/L, Hb ≥85 g/L, ALB ≥28 g/L, TBIL ≤ 1.5 × ULN, ALT and AST ≤ 3 × ULN, Cr ≤ 1.5 × ULN or CrCl ≥40 mL/min, FEV1 ≥ 1 L. (liver metastases ALT and AST ≤ 5 × ULN, liver or bone metastases AKP ≤ 5 × ULN).(9) Enrolled voluntarily and signed informed consent by the patient himself or his legal representative. Exclusion Criteria: 1. Pregnant or lactating women. 2. Lung V20 remains over 25%. 3. Confirmed diagnosis or clinical suspicion of esophageal fistula. 4. Recurrence in the irradiated field. 5. Active infection requiring systemic therapy. 6. Active autoimmune disease requiring systemic treat-ment in the past 2 years. 7. Immunodeficiency diagnosis, systemic steroid therapy, or any immunosuppressive treatment within 7 days before the first study treatment dose. 8. Patients with a known history of grade 3 or higher adverse events, which are unsuitable for Anti-PD-1 therapy or adverse events that have not recovered to ≤CTCAE grade 1 (except alopecia). 9. Uncontrolled pleural effusion, pericardial effusion, or pelvic ascites requiring repeated drainage. 10. Unable or rejection to receive Anti-PD-1 therapy or unable to comply with study requirements or follow-up schedule.(11) Inability to provide informed consent. \-