2874 - A Randomized, Single-Center, Phase II Trial of Endoscopic NBI Combined with MRI to Guide the Individualized Clinical Target Volume Delineation in Eccentric Nasopharyngeal Carcinoma

Purpose/Objective(s): We aimed to evaluate the efficacy and toxicities after NBI combined with MRI-guided individualized clinical target volume (CTV) delineation in eccentric nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy.

Materials/Methods: We conducted a randomized, single-center, phase II clinical trial. Patients with a nasopharyngeal mass confined to 1 side of the nasopharynx or did not exceed the midline. Patients with negative contralateral retropharyngeal lymph nodes and no clivus involvement were eligible. 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 (individualized CTV) or a control group (conventional CTV) to evaluate the efficacy and safety of the 2 groups. For individualized CTV, the contralateral CTV1 was defined as a subclinical disease consisting of 5mm margin surrounding GTVnx (not including entire nasopharynx mucosa); The CTV2 was defined as potentially involved regions consisting of 5mm margin surrounding CTV1, and contralateral CTV2 only included the pharyngeal recess. The primary endpoint are acute adverse reactions and control rate of non-irradiated area. The secondary objectives are 3-year local recurrence-free survival (LRFS), overall survival (OS), progress-free survival (PFS), quality of life.

Results: From May 1, 2023, to November 19, 2024, 44 patients with nasopharyngeal carcinoma were randomly assigned in a 1:1 ratio to the experimental group (n=22) or the control group (n=22). The average volume of CTV1 in the experimental group was 71.7 cm³, while that in the control group was 101.4 cm³. With a median follow-up of 10 months, the acute adverse reactions (xerostomia, taste alteration, dysphagia, & mucositis) in the experimental group were milder than those in the control group. Specifically, significant differences in xerostomia (25.4 ± 8.2 vs 39.6 ± 9.7, p < 0.001) and taste alteration (32.1 ± 14.9 vs 46.7 ± 12.0, p < 0.001) emerged after the 10th radiotherapy session, while significant differences in dysphagia (grade 2-3: 31.8% vs 95.4%, p < 0.001) and mucositis (grade 2-3: 63.7% vs 100%, p = 0.002) were observed after the 20th radiotherapy session. The follow-up was concluded on Jan 20, 2025, and no recurrence in non-irradiated areas was observed in either group. TBD.

Conclusion: This clinical trial initially confirmed that the combination of endoscopic narrow-band imaging and magnetic resonance imaging-guided individualized clinical target volume delineation for eccentric nasopharyngeal carcinoma significantly reduced acute toxic and side effects without increasing the risk of recurrence, thereby improving the quality of life of patients. The 3-year LRFS, OS, and PFS need further clinical observation & follow-up to be determined. Currently, the enrollment is still ongoing. TBD. Clinical Trial number: NCT06167109.