Acoustic neuroma radiosurgery with marginal tumor doses of 12 to 13 Gy

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

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“…For SRS for VS, the prescription dose should be limited to 12–14 Gy for hearing preservation (24, 25, 33). …”

Section: Recommended Dose–volume Limits (Where Possible While Retamentioning

confidence: 99%

Radiation Therapy and Hearing Loss

Bhandare

Jackson

Eisbruch

et al. 2010

International Journal of Radiation Oncology*Biology*Physics

223

139

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“…This criterion was chosen because there is evidence in the literature that differences in tumor size of the order of 2 mm cannot be reliably measured, even by the same radiologist (8). Also, in the radiotherapy literature, the criteria for growth are commonly reported as an increase in diameter of greater than 2 mm in 1 direction (9). Kaplan-Meier curves for no-growth and no-intervention rates were plotted for the entire group.…”

Section: Variables and Statistical Analysismentioning

confidence: 99%

Vestibular Schwannoma

Solares

Panizza

2008

Otology &Amp; Neurotology

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“…[12] With reduction in the marginal dose, a high rate of tumor growth arrest can be achieved with minimal toxicity to the cranial nerves. [3] In a large series by Hasegawa et al, the 5-and 10-year PFS (Progression-free Survival) rate was 93 and 92%, respectively. Treatment failure (6.9%) developed within 3 years after treatment.…”

Section: Discussionmentioning

confidence: 95%

“…[2] Many studies have demonstrated the efficacy of gamma knife for the treatment of neuromas, with tumor control rates of more than 95%. [3][4][5] With the introduction of linear accelerators especially adapted for SRS, linac-based SRS has become an alternative to gamma knife radiosurgery. There have been relatively few studies on linac-based SRS for neuromas and, moreover, these studies have been on small samples and have had short follow-up periods; nevertheless, linac-based SRS has been shown to be comparable to gamma knife radiosurgery with respect to local control and complications.…”

Section: Introductionmentioning

confidence: 99%