Hearing function in patients with nasopharyngeal carcinoma after three-dimensional conformal radiotherapy or intensity modulated radiotherapy: a prospective cohort study

BACKGROUND: Nasopharyngeal carcinoma (NPC) is Indonesia's most common head and neck malignancy, accounting for 60% of all such malignancies. The leading choice of treatment for nasopharyngeal carcinoma, especially in the early stages, is radiotherapy. The 5-year survival rate of early-stage NPC therapy with radiotherapy alone is above 90%. However, auditory organ structures and parts of the auditory system that receive high doses of radiotherapy show various radiotherapy-induced injuries to the outer, middle, and inner ear. This study aimed to assess the effect of three-dimensional conformal RT (3D -CRT) exposure with intensity-modulated radiation therapy (IMRT) on hearing function in patients with NPC. METHODS: This prospective cohort study was carried out at Dr. Wahidin Sudirohusodo Hospital and Hasanuddin University Hospital, Makassar, Indonesia, from February to July 2022. Pure tone audiometry, tympanometry, and otoacoustic emission were examined before and three months after radiotherapy in 18 patients with NPC who underwent 3D -CRT radiotherapy or IMRT. The hearing threshold analysis was tested using a paired t -test, with the significance of the test determined based on a P value of <0.05. The condition of the middle ear and outer hair cells was analyzed using the Wilcoxon non-parametric test with the significance level set to <0.05. RESULTS: We found an ototoxic effect in 44% of the samples. The average hearing threshold on the air and bone conduction examination showed a decrease in hearing function, especially at a frequency of 4000 to 8000 Hz (P<0.05). There was no effect of giving IMRT modality in minimizing complications of hearing loss in patients with NPC compared to 3D -CRT (P>0.05). CONCLUSIONS: Patients with NPC who underwent 3D -CRT and IMRT had impaired function of the cochlea's outer hair cells. Further research needs to be done using more samples and a longer evaluation duration.