Long-term hearing status after radiotherapy for nasopharyngeal carcinoma

This paper evaluates the hearing status in the long-term, of patients who have had radiotherapy for nasopharyngeal carcinoma (NPC) and also discusses the hearing losses from a disability point of view, which takes into account binaural hearing. Forty patients who have had NPC successfully treated by a single radical course of radiotherapy of 70-80 Gy were studied at 2-12 years (mean 6.2 years) after radiotherapy. Each patient was examined clinically and with a pure-tone audiogram. Averaged hearing thresholds over 0.5, 1.0, 2.0 and 4.0 kHz were evaluated and a value > 30 dB was considered abnormal. The findings were compared with age-matched controls. The median hearing threshold for each ear in NPC patients was found to be 31.9 dB (range 10.0-86.3 dB) and that for controls 17.5 dB (7.5-38.8 dB) (P < 0.0005, Wilcoxon's matched pairs test). In NPC patients, 44 ears (55.0%) had abnormal hearing, of which 17 (21.3%), 5 (6.3%) and 22 (27.5%) ears had predominantly sensori-neural, conductive and mixed hearing losses, respectively. Nineteen ears had middle ear effusions, accounting for the majority of mixed and conductive hearing losses. In terms of individual patients, 8 (20.0%) and 18 (45.0%) patients had abnormal hearing in one year (monaural hearing disability) and both ears (binaural hearing disability), respectively. In conclusion, a substantial proportion of patients who have had radiotherapy for NPC, have hearing disability in the long-term, as compared to normal controls.