Permanent unilateral hearing loss after radiotherapy for parotid gland tumors

BACKGROUND: The purpose of this retrospective study was to determine the long-term effects of radiotherapy on hearing function in patients who underwent parotidectomy and postoperative radiotherapy for unilateral tumors of the parotid gland. METHODS: An extensive set of tests was used to measure hearing loss. The mean dose on middle ear, cochlea, and Eustachian tube was estimated with a CT-planning system. RESULTS: A hearing loss of > or = 15 dB in 3 frequencies was found in 32% of the 52 patients included in the study. Patients with an asymmetrical hearing loss received a higher mean dose on the hearing structures (p < .002). The threshold dose for clinically relevant hearing loss was found at 50 Gy on the cochlea and Eustachian tube. CONCLUSIONS: Radiation-induced hearing loss is a common complication. A mean dose of > 50 Gy on the cochlea should be avoided.