Auditory Preservation in Nasopharyngeal Carcinoma: Comparison of Proton and Photon Radiotherapy

OBJECTIVE: To compare cochlear dose and hearing outcomes between intensity-modulated proton therapy (IMPT) and volumetric modulated arc therapy (VMAT) in patients with nasopharyngeal carcinoma (NPC). STUDY DESIGN: Prospective matched cohorts. SETTING: Tertiary academic center. METHODS: A total of 180 newly diagnosed, treatment-naive NPC patients receiving definitive radiotherapy between 2023 and 2025 were enrolled. Patients were 1:1 matched by sex, age, and disease stage, and assigned to IMPT (n = 90) or VMAT (n = 90). Mean cochlear dose was recorded. Audiological evaluations, including pure-tone audiometry (PTA), air-bone gap, and word recognition score, were performed before and after treatment. RESULTS: IMPT delivered significantly lower mean doses to the ipsilateral (47.51 vs 56.82 Gy, P < .001; 95% CI: -14.27 to -4.35) and contralateral cochlea (30.79 vs 45.71 Gy, P < .001; 95% CI: -18.93 to -10.91). Based on each patient's most recent audiometric assessment (median follow-up, 12.1 months; range, 7.5-19.5 months), IMPT demonstrated better average PTA thresholds than VMAT (33.72 vs 42.00 dB; P = .016; 95% CI, -14.91 to -1.65), superior high-frequency hearing at 2 to 8 kHz (37.94 vs 53.82 dB; P < .001; 95% CI, -23.69 to -8.07), lower air-bone gap (5.67 vs 10.62 dB; P < .001; 95% CI, -6.80 to -3.10), and higher word recognition scores (96.67% vs 94.00%; P = .039; 95% CI, 0.14-5.20), with less bone conduction loss at 1 to 4 kHz. CONCLUSION: IMPT reduces cochlear dose compared to VMAT, resulting in better hearing preservation and suggesting its potential to minimize ototoxicity in NPC patients.