De-escalation Radiation Strategy After NAC in Combination With ICI in LAHNSCC

Inclusion Criteria: 1. ≥18 years old, with medical decision-making capacity 2. Signed informed consent 3. ECOG score of 0-1 4. Pathologically diagnosed with oral cancer, oropharyngeal cancer, laryngeal cancer, or hypopharyngeal cancer 5. Exclusion of distant metastasis 6. Clearly evaluable lesion (per RECIST 1.1 criteria) 7. Expected life span ≥6 months 8. Laboratory test results meet the following requirements: WBC ≥ 3×10\^9/L, ANC ≥ 2.0×10\^9/L, PLT ≥ 80×10\^9/L, Hb ≥ 80g/L (according to the normal standards of the central laboratory); Liver function: Total bilirubin, ALT, and AST all ≤ 1.5x UNL (upper normal limit); AST (SGOT)/ALT (SGPT) ≤ 2.5 x IULN (upper normal limit); Kidney function: Cr ≤ 1.5x UNL (upper normal limit), and creatinine clearance rate ≥ 60 ml/min (calculated using the Cockcroft and Gault formula); Thyroid function T3 and T4 within the normal range (hypothyroidism can be corrected with oral thyroid hormone supplementation); Heart function: All three cardiac enzymes and pro-BNP within the normal range, no history of heart attack; Adrenal function: Normal cortisol secretion function or correctable based on endocrine assessment 9. HBV-infected patients with HBV-DNA copy numbers less than 500 IU/ml 10. No history of other malignant tumors in the past 5 years (excluding basal cell carcinoma of the skin and thyroid cancer). Exclusion Criteria: 1. No indications for curative radiotherapy or contraindications to radiochemotherapy. 2. Clinical factors identified by the investigator that could potentially affect the completion of the study protocol (such as bleeding, active infection, or mental factors). 3. Patients requiring long-term maintenance steroid therapy (including oral and intravenous use); local use or inhalation can be included in the study. 4. Previous history of autoimmune diseases or in the active phase of the disease \[including but not limited to inflammatory bowel disease (IBD), rheumatoid arthritis, autoimmune hepatitis, systemic sclerosis (scleroderma and its variants), systemic lupus erythematosus, autoimmune vasculitis, autoimmune neuropathies (such as Guillain-Barré syndrome)\], vitiligo, and correctable endocrine deficiencies such as hypothyroidism and physiological cortisol deficiency can be included in the study and are not exclusion criteria. 5. History of active tuberculosis or non-infectious pneumonia or any clinical evidence. 6. Active phase of viral hepatitis, HBV DNA \> 500 IU/ml. 7. Acquired Immunodeficiency Syndrome (AIDS). 8. Concurrent severe medical conditions (including heart diseases) with coexisting diseases or conditions affecting the patient's normal enrollment or safety during the study. 9. Prior immunotherapy for other tumors. 10. History of other malignant tumors within 5 years (excluding cured basal cell carcinoma of the skin or thyroid cancer). 11. Pregnant or lactating women. 12. Concurrently suffering from other malignant tumors. 13. Cannot or unwilling to sign the informed consent form. 14. Vaccination within 4 weeks. 15. Allergic reaction to the investigational drug.