ObjectiveTo explore the correlation between the dose of the cochlea and the tolerable threshold of cochlear injury induced by intensity modulated chemotherapy and radiotherapy for nasopharyngeal carcinoma. MethodsA hundred initial nasopharyngeal carcinoma patients (192 ears) receiving intensity modulated chemotherapy and radiotherapy were selected. The results of pure tone audiometry and acoustic immittance measurement were normal in all cases. The intensity modulated chemotherapy dose of GTVnx was 2.25Gy per time, and the average dose of GTVnx was 68-74.2 Gy. The chemotherapy plan: DDP 80 mg/m2, once every 3 weeks, 2-3 cycles. The pure tone audiometry and acoustic immittance measurement were conducted before chemoradiotherapy, after 3 months, 6 months, 1 year and 2 years of chemoradiotherapy. Hearing impairment was defined as the ascending range of high-frequency hearing threshold value＞15 dB. The age at definite diagnosis, gender, TNM stage and mean dose of cochlea were involved in multivariate analysis, and the results of audiology test and the average dose of the cochlea were statistically analyzed. ResultsThe incident rates of ear hearing impairment after 3 months, 6 months, 1 year and 2 years of chemoradiotherapy were 14.20% (25/176), 22.73% (40/176), 27.27% (48/176) and 34.66% (61/176) respectively. Multivariate analysis for hearing loss of patients showed that the age at definite diagnosis and the mean dose of cochlea correlated with sensorineural hearing loss after chemoradiotherapy for nasopharyngeal carcinoma(P＜0.05). The mean threshold dose of the cochlea was 40Gy when the nasopharyngeal cancer patients suffered from deterioration of high-frequency hearing threshold value after 2 years of chemoradiotherapy(P＜0.05). ConclusionIn the intensity modulated chemotherapy and radiotherapy for nasopharyngeal carcinoma, the incidence of hearing loss can be reduced when the average dose of the cochlear for tolerable threshold was limited to the level less tan 40Gy.

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