Clinical analysis of risk factors for sensorineural hearing loss in patients with nasopharyngeal carcinoma after intensity-modulated radiotherapy

Abstract

Objective To investigate the risk factors for sensorineural hearing loss (SNHL) in patients with nasopharyngeal carcinoma (NPC) after intensity-modulated radiotherapy (IMRT).Methods From January 2012 to January 2013,29 patients with histopathologically confirmed NPC who received radiotherapy alone or concurrent chemoradiotherapy were included in this study.All patients underwent hearing tests,including pure tone audiometry and acoustic immittance measurement,before and after the IMRT.The cochlear doses for each ear were also collected for analysis.A prospective analysis was performed to investigate the relationship between cochlear dose and SNHL in patients with NPC,and the effects of other factors,including time after radiotherapy,chemotherapy,T stage,and age,were also analyzed.Results Of the 58 ears studied,6(10％) had low-frequency SNHL,and 17 (29％) had highfrequency SNHL.There were significant differences in mean cochlear doses between the patients who developed SNHL after radiotherapy and those who did not (left ears:46.1 Gy vs.35.5 Gy,P =0.006;right ears:45.0 Gy vs.35.8 Gy,P =0.009).When the mean cochlear dose was less than 44 Gy,only 15％ (6/38) of ears had high-frequency SNHL.The invasion of skull base bone was also a significant risk factor for SNHL(P =0.047),but age,chemotherapy,and time after IMRT were not significant risk factors.Conclusions The mean cochlear dose and invasion of skull base bone are significant risk factors for SNHL in patients with NPC after radiotherapy.It is recommended that the mean cochlear dose should be limited to 44 Gy to minimize the incidence of SNHL after IMRT. Key words: Nasopharyngeal neoplasms/intensity-modulated radiotherapy; Sensori-neural hearing loss; Pure tone audiometry; Acoustic immittance