Ototoxicity after radiotherapy for head and neck tumors

To investigate the incidence of radiation-induced ototoxicity according to the total dose delivered to specific parts of the auditory system, fractionation, and chemotherapy.

Records of 325 patients treated for primary extracranial head and neck tumors with curative intent who received radiotherapy between 1964 and 2000 (median follow-up, 5.4 years) were retrospectively reviewed. Reconstructions of the treatment plans were generated to estimate the doses received by components of the auditory system.

Radiotherapy-induced morbidity developed in 41.8% of patients (external ear, 33.2%; middle ear, 28.6%; and inner ear, 26.8%). Univariate/multivariate analyses indicate that total dose received by parts of the auditory system seem to be significant, though fractionation and chemoradiation may contribute to the incidence of ototoxicities. Sensorineural hearing loss (SNHL) was observed in 49 patients (15.1%). Univariate and multivariate analyses indicated that age (p = 0.0177 and p = 0.005) and dose to cochlea (p < 0.0001 and p < 0.0001) were significant, and chemoradiation (p = 0.0281 and p = 0.006) may increase the incidence of SNHL. Five-year and 10-year actuarial risk of clinically overt SNHL increased to 37% (p > 0.0001) above doses of 60.5 Gy compared to 3% at doses below 60.5 Gy. For patients treated with adjuvant chemotherapy, clinically overt SNHL increased to 30% compared to 18% in the no-chemotherapy group at 10 years (p = 0.0281).

Radiotherapy toxicity was observed in all parts of the auditory system with median doses for incidence varying between 60 Gy to 66 Gy. Total dose to organ seems to be a significant factor though fractionation and chemo-radiation may contribute to ototoxicities.