A long-term study on hearing status in patients with nasopharyngeal carcinoma after radiotherapy

To study the long-term sensorineural hearing status after radiotherapy in patients suffering from nasopharyngeal carcinoma.

A prospective study of 220 patients (395 ears) with a median follow-up of 36 months.

A university hospital.

Four criteria were needed. The patient had to have had at least 12 months of audiologic follow-up, no concurrent chronic ear disease, no direct tumor invasion of ear, and no significant sensorineural hearing loss before radiotherapy.

Pure-tone audiography and impedance audiometry-which were performed before and at the third month after completion of radiotherapy and at a yearly interval thereafter-formed the basis of the study.

The significance level in this study was defined as a bone conduction threshold increase of more than 10 dB between the initial audiogram and those obtained after the completion of radiotherapy. An increase of more than 30 dB was defined as severe loss.

Paired t test indicated that the mean bone conduction threshold before and after radiotherapy were significantly different (paired t test, p < 0.05). Logistic regression showed that patient age was related to the significant loss at speech frequency but not to the loss at 4 kHz. The presence of postradiation otitis media with effusion, preirradiation hearing status, and addition of chemotherapy were found to be not influential on hearing change.

Hearing deterioration may begin as early as 3 months after the completion of radiotherapy. Early change may be transient, but the effect of radiation on hearing tended to be chronic and progressive.