Omega-3 Fatty Acids With PD-1 Inhibitors in Advanced Esophageal Cancer

Inclusion Criteria： Age ≥18 years; ECOG 0-2. Histologically confirmed recurrent/metastatic esophageal cancer (AJCC 8th; de novo stage IV or relapse after prior therapy). PD-1 inhibitor naïve, or prior PD-1 stopped \>3 months with subsequent progression (not primary PD-1 resistance). Adequate organ function per protocol (hematologic, hepatic, renal). Women of childbearing potential: negative pregnancy test and agree to effective contraception. Signed informed consent. Exclusion Criteria： PD-1 inhibitor resistance or refractory disease to prior PD-1. Esophageal fistula present or strongly suspected. Active autoimmune disease or immunodeficiency requiring systemic therapy (protocol-defined exceptions allowed, e.g., treated hypothyroidism; controlled type 1 diabetes). Systemic corticosteroids or other immunosuppressants requiring ongoing use (physiologic or topical steroids allowed). Interstitial lung disease/pneumonitis history or active pneumonitis on screening CT. Uncontrolled cardiovascular disease (e.g., NYHA ≥ II heart failure, unstable angina, recent MI, significant uncontrolled arrhythmias). Serious active infection, including active TB; uncontrolled viral hepatitis (active HBV/HCV per protocol). Pregnant or breastfeeding. Recent major surgery (per protocol window) or high bleeding risk/therapeutic anticoagulation not suitable for omega-3 use. Other conditions that, in investigator's judgment, preclude protocol compliance or safety.