This is a prospective, single-center clinical trial in eccentric nasopharyngeal carcinoma (NPC) patients. The aim of this study is to evaluate the efficacy and safety of NBI combined with MRI-guided optimized CTV compared with conventional CTV, and to compare the radiotherapy-related adverse events and quality of life between the two groups.

All patients with eccentric nasopharyngeal carcinoma were selected on the basis of MRI findings and NBI endoscopy was performed in these patients. The patients were enrolled if both NBI endoscopy and MRI showed eccentric NPC. Patients with contralateral tissue mucosal abnormalities detected by NBI and confirmed by biopsy were excluded. Then the patients were randomly divided into an experimental group (Optimized CTV) or a control group (Conventional CTV) to evaluate the efficacy and safety of the two groups, as well as radiotherapy-related adverse events.

Inclusion Criteria:

1. Males and females ≥18 years of age;
2. ECOG Performance Status 0,1 or 2;
3. Pathologically diagnosed as nasopharyngeal carcinoma;
4. Pretreatment nasopharynx and neck MRI imaging;
5. Nasopharyngeal suspected lesions were examined by NBI endoscopy;
6. Meeting the definition of eccentric NPC with ipsilateral (affected side) staging of T1-4 and contralateral (healthy side) staging of T0;
7. Patients evaluated without contraindications to radiotherapy;
8. Voluntary participation in clinical research, and signed informed consent.

Exclusion Criteria:

1. Patients who did not successfully undergo all three examinations (MRI, NBI, and endoscopic biopsy);
2. Other rare pathological types, such as adenocarcinoma;
3. Patients with tumor invasion of the clivus;
4. Patients whose contralateral retropharyngeal lymph nodes met the diagnostic criteria;
5. Invasion of paranasal sinuses (except simple sphenoid invasion).