The performance of the predictive models for the occurrence and severity of oropharyngeal mucositis established using either oral cavity contouring method or mucosa surface contouring method was unsatisfactory in nasopharyngeal carcinoma (NPC). Whereas the predictive model of a mucosal contouring method based on swallowing-induced breakthrough pain exhibited better overall performance in locally advanced NPC. Therefore, the investigators aimed to conduct a prospective, multicenter, real-world observational study to further assess the predictive efficacy of this mucosal delineation method for radiation-induced oropharyngeal mucositis in NPC.

Swallowing-induced breakthrough pain as a prominent clinical challenge for radiation-induced oropharyngeal mucositis, occurs in almost all patients with nasopharyngeal carcinoma (NPC) undergoing radiotherapy, and has a significant impact on patients' quality of life and treatment outcomes. Radiation-induced oropharyngeal mucositis is closely related to the irradiated dose and volume, and the performance of the predictive models for its occurrence and severity established using either oral cavity contouring method or mucosa surface contouring method was unsatisfactory. Thus, it is difficult to carry out risk assessment, precise screening and early intervention through dosimetric parameters, thereby reducing the occurrence of severe radiation-induced oropharyngeal mucositis. The investigators defined a delineation method based on the mucosal areas of radiation-induced injury resulting in swallowing-induced breakthrough pain in locally advanced NPC, and our preliminary results demonstrated that the predictive model exhibited better overall performance. Therefore, the investigators aimed to conduct a prospective, multicenter, real-world observational study to further explore the predictive efficacy of this mucosal delineation method for radiation-induced oropharyngeal mucositis in NPC.

Inclusion Criteria:

1. Provide informed written consent.
2. Age ≥ 18 years.
3. Histologically confirmed as nasopharyngeal carcinoma, and currently undergoing radical radiotherapy or chemoradiotherapy.
4. Complete and continuous records of oral / oropharyngeal mucositis grading, and self-reported swallowing-induced breakthrough pain.

Exclusion Criteria:

1. Existence of poor oral hygiene, untreated dental or periodontal diseases, and metal dental restorations.
2. Current untreated or unresolved conditions like unstable heart diseases requiring treatment, and poorly controlled diabetes mellitus.
3. Body mass index (BMI) <18.5.
4. Unsuitable to participate in current study, according to researchers' assessment.

Patients with nasopharyngeal carcinoma receiving radical radiotherapy or chemoradiotherapy