Radiotherapy is the main treatment method for head and neck tumors. However, almost all patients with head and neck tumors will develop acute inflammatory reactions such as Radiotherapy-Induced Oral Mucositis (RIOM) after receiving Radiotherapy, resulting in a decline in the quality of life of patients, hindering the smooth implementation of the treatment plan, reducing the therapeutic effect, and increasing the economic burden of patients. However, the current treatment strategies for RIOM focus on symptomatic treatment and have little impact on the course, severity and related complications of mucositis. Therefore, exploring effective strategies, predicting the incidence and severity of RIOM in patients, and providing prevention and treatment are the clinical bottlenecks and cutting-edge issues that urgently need to be solved in the current clinical practice of radiotherapy for head and neck tumors. Previous studies have shown that the steady-state of metallic elements may be closely related to the occurrence and development of RIOM. Therefore, we plan to conduct a prospective, single-center, observational study to further explore the correlation between metal elements and severe RIOM, analyze its predictive efficacy, and observe the dynamic changes of metal elements in radiotherapy.

Inclusion Criteria:

1）Sign the informed consent form; 2) Confirmed by pathological biopsy as nasopharyngeal carcinoma or head and neck tumors; 3) Have indications for radiotherapy and voluntarily accept radiotherapy; 4) ECOG PS: 0/1; 5) Age: 18-75 years old; 6) Laboratory tests confirm good organ function.

Exclusion Criteria:

1. There are contraindications for radiotherapy;
2. Combined with other tumors;
3. Pathological sections could not be obtained;
4. The patient has any serious concurrent diseases that may pose unacceptable risks or have a negative impact on trial compliance. For instance, unstable heart diseases requiring treatment, chronic hepatitis, kidney diseases with poor conditions, uncontrolled diabetes (fasting blood glucose greater than 1.5 × ULN), and mental disorders;
5. The researcher judged that it was not suitable to participate in this study.

According to the 2021CSCO guidelines, patients diagnosed as nasopharyngeal carcinoma and head and neck tumors were standardized