PO-1052 Cyberknife stereotactic radiotherapy for vestibular schwannomas :a single institution experience

Purpose or Objective :
Report our experience of fractionated stereotactic radiotherapy Cyberknife (CK) for vestibular schwannoma (VS) in order to asses the posttreatment clinical symptoms, tumor control and post treatment auditory function.
Materials and Methods :
Retrospective analysis of 45 VS patients treated by CK from 2010 to 2016, classified in location and size according to Portman-Bebear and Koos (PBK) and according to 2 audiometric scales: the International Bureau of Audiophonology (BIAP) and the Gardner Robertson scale (GR). Data including CK treatment parameters, pre and post CK clinical signs, pre and post CK tumor volumes and auditory parameters were collected and examinated.
Results : 80% of the pre CK clinical symptoms of our 45 patients improve in post-CK and 20% increase slightly. 77.3% of patients, with a mean post CK magnetic resonance imaging (MRI) follow-up of 31.5 months, had an excellent tumor control. Excluding 2 patients who died in post CK and 8 pre CK cophosis patients, 21 (60%) of the remaining 35 BIAP patients, with a mean audiometric post CK follow-up of 33.65 months, maintained a good pre CK comparable audiometric stabilization. The other fourteen BIAP patients (40%) experienced variable hearing impairment (33.3% had slight increased hearing thresholds from 10 to 24dB in pure tone audiometry) which is not related to a pre CK high tumor volume (tV).