Radiation-induced hearing impairment—a pilot study in patients treated for malignant parotid tumours

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Abstract
There are few reports in the literature concerning the long-term effects of radiation on hearing. A recent paper reviewed eight studies which estimated the incidence of post-irradiation hearing loss at 0–54% (Talmi et al, 1989). The nature of the impairment is unclear, since both sensorineural and conductive deafness are reported. Most surveys have studied patients with cancer of the nasopharynx or paediatric tumours, the management of which require bilateral radiotherapy techniques, thus any deterioration in hearing that may occur after radiotherapy (XRT) owing to the lack of controls cannot be definitely ascribed to the effects of ionizing radiation.Radical radiation of parotid tumours involves unilateral techniques which encompass the entire ear. The 10 year survival from parotid tumours is high—71% at the Princess Margaret Hospital (PMH) (Theriault & Fitzpatrick, 1986)—and, therefore, such patients are ideal candidates to be evaluated for the long-term effects of XRT on the ear. We recently reviewed 269 patients with malignant parotid tumours treated at PMH between 1970 and 1986 and noted that 10 patients out of 202 who received XRT reported unilateral hearing loss during follow-up. This number may be an underestimate of the true incidence because auditory function is not routinely discussed at routine follow-up visits.Therefore, in an attempt to elucidate the magnitude of this problem, we contacted all patients in the above survey treated between 1978 and 1983, who therefore had at least 7 years of follow-up, and we requested their attendance for a formal audiometric evaluation.
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