Head and neck squamous cell carcinoma (SCC) is the sixth most common cancer worldwide, with more than 700,000 new cases and more than 350,000 deaths each year. At present, radiotherapy is an important measure to control the recurrence of head and neck tumors, but almost all patients with head and neck squamous cell carcinoma will have acute inflammatory reactions such as radiotherapy-induced oral mucositis (RIOM) after radiotherapy, which seriously affects the quality of life and radiotherapy efficacy of patients. Serum amyloid A1 (SAA1) is an acute phase protein associated with inflammation. Our previous basic research found that serum SAA1 expression levels can be used as biomarkers to assess the dose received by the receptor in the early stages of radiation damage. At the same time, we confirmed that the serum level of SAA1 in patients with nasopharyngeal carcinoma increased after radiotherapy. Therefore, we intend to conduct a prospective, multicenter, observational study to further explore the predictive power of plasma SAA1 levels for radiotherapy-induced oral mucositis, with a view to early screening and prevention of RIOM patients.