Radiation Therapy and Hearing Loss

Abstract

A review of literature on the development of sensorineural hearing loss after high-dose radiation therapy for head-and-neck tumors and stereotactic radiosurgery or fractionated stereotactic radiotherapy for the treatment of vestibular schwannoma is presented. Because of the small volume of the cochlea a dose-volume analysis is not feasible. Instead, the current literature on the effect of the mean dose received by the cochlea and other treatment-and patient-related factors on outcome are evaluated. Based on the data, a specific threshold dose to cochlea for sensorineural hearing loss cannot be determined; therefore, dose-prescription limits are suggested. A standard for evaluating radiation therapy-associated ototoxicity as well as a detailed approach for scoring toxicity is presented. KeywordsRadiotherapy; Sensorineural hearing loss; Ototoxicity; Auditory; Ear; QUANTEC CLINICAL SIGNIFICANCERadiation therapy (RT) may damage the cochlea and/or acoustic nerve, leading to sensorineural hearing loss (SNHL) (1-4), with resultant long-lasting compromise in the quality of life. This report focuses on RT-induced SNHL in adults who have received fractionated RT, stereotactic radiosurgery (SRS), and fractionated stereotactic RT (FSRT) for head-and-neck cancers and vestibular schwannomas (VS). ENDPOINTSSNHL is traditionally defined as a clinically significant increase in bone conduction threshold (BCT) at the key human speech frequencies (0.5-4.0 kHz), as seen in pure-tone audiometry. However, reports of SNHL after fractionated RT vary in terms of: (a) the frequencies evaluated (e.g., 2 or 4 kHz alone (5,6) and/or pure tone average [PTA] of

Radiotherapy for vestibular schwannoma: Review of recent literature results

“…A crucial issue remains the dose constraints for critical structures, first of all the inner ear that should be respected in order to limit long term side effects. [34][35][36][37][38] These constraints change by using different fractionation schedules and have to be taken carefully into account, especially when using a single shot radiation as in SRS (Table 3).…”

Use of gEUD for predicting ear and pituitary gland damage following proton and photon radiation therapy

“…Because of the small volume of the cochlea and the pituitary gland, dose-volume analysis has been rarely performed and only mean dose effects have been mainly reported. 13,14 As steep dose gradients can be achieved with proton beams (and a fortiori with combined photon-proton beams as discussed in Feuvret et al 8 ), we considered that non-uniform doses could be delivered within the organ volume and that dose-volume analysis could be evaluated for partial volumes of the OARs. The first step consisted of estimation of the value of parameter a, for which a model can be built with gEUD that best describes the data.…”

Comparison of treatment plans: a retrospective study by the method of radiobiological evaluation

“…These constraints included no more than 50% of bladder volume to receive a dose greater than 6500 cGy (V 50 ≤ 65%), no more than 50% of rectum to receive a dose of 5000 cGy (V 50 < 50%) and different D max / D mean for rest of the OARs. All these figures are summarized in Table 1 [6][7][8][9][10][11][12][13][14][15]. For the comparison of treatment plans, a radiobiological based plan evaluation was also carried out.…”