THREE FRACTION STEREOTACTIC RADIOTHERAPY (SRT) FOR VESTIBULAR SCHWANOMMA: THE WESSEX EXPERIENCE

Abstract

Abstract AIMS Retrospective review of SRT for vestibular schwannoma. University Hospital Southampton treat tumour vol umes max 2.5cm in diameter without brainstem compression with 21Gy/3#. This reviews the experience of local control and toxicity profile in our centre and the impact of limiting dmax. METHOD Retrospective analysis of patients treated for radiologically diagnosed vestibular schwannoma from 2019 to present. Patient notes, audiograms, imaging and radiotherapy planning system were reviewed for data collection. No patients were removed from analysis due to missing data. RESULTS 36 patients have been treated with three fraction SRT. Median age 68 (47-83). PTV volume from 1.03cm3 to 5.52cm3 (median 2.37cm3). All patients have radiologically stable disease to date, with 14 patients (38.9%) having objective tumour response on imaging. 9 patients had serviceable hearing at baseline and 1 remained serviceable at follow up. 7 (19.4%) patients experienced treatment-related toxicity. 6 patients reported facial nerve toxicity in which 4 (66.7%) this was self-limiting with full recovery. 2 patients had persistent facial nerve symptoms (House-Brackmann score 2, and 3 respectively). Those with dmax <26Gy (n=15) experienced this less with only 1 patient experiencing facial nerve toxicity (House-Brackmann score 2). CONCLUSIONS Three fraction SRT provides excellent local control with high levels of objective radiological response in tumours up to 4cm3, however, long term follow-up is required. This treatment has acceptable toxicity with most symptoms resolving spontaneously. Permanent facial nerve toxicity was seen in 2 (5.6%) of patients. By limiting dmax to <26Gy the rate of facial nerve toxicity is reduced significantly.