Optimization of Treatment Strategy for Unresectable cN3 Esophageal Squamous Cell Carcinoma

Inclusion Criteria: * Esophageal squamous cell carcinoma confirmed through histopathology. * Distant metastasis excluded by CT, MRI, or PET/CT examinations. * Locally advanced stage: AJCC/UICC eighth edition staging with any T, N3M0. * Expected survival time of at least 6 months. * With an ECOG performance status of 0 to 2. Not accompanied by severe pulmonary hypertension, cardiovascular disease, peripheral vascular disease, severe chronic heart disease, or other comorbidities that could impact radiotherapy progress. * Adequate function of major organs: Hematopoietic function: Hemoglobin ≥100g/L, platelets ≥90×109/L, white blood cells ≥4×109/L. Exceptions may be considered for patients with ECOG 0-1 who have a history of chronic anemia (80-100 g/L), previous low white blood cell levels (3-4×109/L), or reduced platelets (80-90×109/L). Liver function: ALT and AST \<1.5 times the upper limit of normal (ULN), bilirubin \<1.5×ULN. Renal function: Serum creatinine (SCR) ≤140 μmol/L. * Patients are required to provide informed consent to undergo treatment. Exclusion Criteria: * Existing or prior history of other malignant tumors (except non-melanoma skin cancer) that are uncontrolled or not cured, depending on the type of the primary tumor. * Lack of histological or cytological diagnosis for esophageal cancer. * Previous chest radiotherapy. * Suffering from innate or acquired immune function defects; * Pregnancy (confirmed by serum or urine β-HCG test) or during the lactation period; History of drug abuse or alcohol dependence; HIV-positive status, including those on antiretroviral treatment; Chronic hepatitis B with viral replication phase; Active phase of hepatitis C; Active syphilis with a history of mental illness that may hinder treatment completion. * Poor overall health status, defined as KPS \< 70 or ECOG \> 2. * Presence of severe comorbidities that could impact radiotherapy progress, including: Unstable angina, congestive heart failure, or myocardial infarction requiring hospitalization within the past 6 months; Acute bacterial or systemic fungal infections; Exacerbation of chronic obstructive pulmonary disease or other respiratory conditions requiring hospitalization; Hepatic or renal insufficiency; Immunosuppressed patients; Coexisting connective tissue diseases, such as active scleroderma or lupus, which are contraindications to radiotherapy. * Inability to comprehend the treatment's purpose or unwillingness to sign the treatment consent form. * Lack of legal capacity or limited legal capacity.