Dose-response relationship and normal-tissue complication probability of conductive hearing loss in patients undergoing head-and-neck or cranial radiotherapy: A prospective study including 70 ears

Abstract

PurposeHead-and-neck (H&N) and cranial radiotherapy may cause hearing loss. Little has been published on the dose-response relationship and normal-tissue complication probability (NTCP) of the conductive subtype of hearing loss. The aims were to observe the incidence of hearing loss in patients undergoing non-intensity-modulated H&N or cranial radiotherapy, obtain the relationship between dose and conductive hearing loss (CHL) and test the current Lyman-Kutcher-Burman (LKB) NTCP model parameters. MethodsThe dose-response in the peripheral auditory system (PAS) of 35 patients (70 ears) was prospectively studied using mean dose and the current LKB model parameters. A wide dose range was obtained by conducting the study at a clinic without advanced treatment techniques. The patients underwent routine external-beam treatments following 3D treatment planning. Hearing status was evaluated by pure-tone audiometry one day before the start and one day and 30 days after the end of radiotherapy. ResultsNineteen ears (27%) experienced hearing loss. Sixteen (23%) had CHL and three (4%) the sensorineural subtype. On average, mean doses of the PAS structures and V95%, V40Gy and V30Gy volumes of the middle-ear planning-organ-at-risk volume (PRV) were significantly greater in ears that suffered CHL. The modelled 50% NTCP of CHL occurred at approximately 30–40 Gy mean dose to middle ear planning organ-at-risk volume. ConclusionsIncidence of conductive hearing loss in non-intensity-modulated radiotherapy of H&N and brain can be significant. CHL exhibits a dose-effect. This suggests that the PAS should be considered in treatment plan optimization. The LKB NTCP model was reasonably accurate but modifications are indicated.