Sapylin Versus Dexamethasone Inhalation for CCRT-Induced Oral Mucositis in Nasopharyngeal Carcinoma

1. Inclusion Criteria: * Stage III-IVa NPC (AJCC 8th edition) diagnosed via pathology in a tertiary hospital; * No previous radiotherapy, chemotherapy, surgery, immunization, or targeted therapy; * Karnofsky Performance Status score ≥80; * Intact and normal oral mucosa before treatment; * Age 18-75 years; * Voluntary participation and provision of informed consent in person; * Routine blood examination: white blood cell count ≥4.0×109/L, hemoglobin ≥100g/L, neutrophil count ≥1.5×10\^9/L, and platelet count ≥100×10\^9/L; * Biochemical examination: total bilirubin ≤1.5×the upper limit of the normal range (ULN), alanine aminotransferase and aspartate aminotransferase ≤2×ULN, and estimated glomerular filtration rate ≥60 mL/min. 2. Exclusion Criteria: * With other malignant tumors in the past or present and/or distant metastasis during treatment; * Who have undergone surgery, chemoradiotherapy, and targeted immunotherapy; * With a history of asthma, rash, urticaria, and other allergic diseases; * With a history of autoimmune diseases, connective tissue diseases, and diabetes mellitus that significantly affect the healing of the oral mucosa; * With concomitant diseases, such as heart disease, kidney disease, and acute infectious diseases, which are judged by the investigator to seriously endanger the safety of patients or affect the completion of the study; * Who are breastfeeding, pregnant, or planning to become pregnant during the study; * With known allergies to the therapeutic agents and penicillin used in the trial; * Mental or nervous system diseases or poor compliance.