A Population-Based Study of Stereotactic Radiosurgery or Fractionated Stereotactic Radiotherapy for Vestibular Schwannoma: Long-Term Outcomes and Toxicities

Publication date: Available online 17 September 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Andrea Lo, Gareth Ayre, Roy Ma, Fred Hsu, Ryojo Akagami, Michael McKenzie, Boris Valev, Ermias Gete, Isabelle Vallieres, Alan Nichol
PurposeThe purpose of the study is to examine long-term local control of vestibular schwannoma (VS) and side effects in patients treated with stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (SRT) in XX-region.Methods and MaterialsFrom August 1998 to May 2009, 207 patients were treated with radiation therapy (RT) at XX-center; 136 (66%) received SRS and 71 (34%) received SRT. Dose prescriptions were 50Gy/25 for SRT and 12Gy/1 for SRS. Our multidisciplinary provincial neuro-stereotactic conference recommended SRT for tumors >3cm and for patients with serviceable hearing (Gardner-Robertson Class I & II).ResultsMedian follow-up was 7.7 years to the last MRI and 6.4 years to the last clinical assessment. Local control for SRS vs. SRT was 94% vs. 87% at 5 years and 90% vs. 85% at 10 years (P=0.2). Five- and 10-year actuarial rates of RT-induced trigeminal nerve dysfunction (TND) were 25% and 25% after SRS, compared to 7% and 12% after SRT (P=0.01). Five- and 10-year actuarial rates of RT-induced facial nerve dysfunction were 15% and 15% after SRS, vs. 13% and 15% after SRT (P=0.93). In the 49 patients with serviceable hearing at baseline who were treated with SRT, hearing preservation was 55% at 3 years, 37% at 5 years, and 29% at 7 years. In multivariable analysis, better pre-treatment ipsilateral pure tone average was significantly associated with hearing preservation (HR 1.03; 95% CI 1.00-1.07; P=0.04).ConclusionsBoth SRS and SRT provided excellent long-term local control of VS. SRS was associated with higher rates of trigeminal nerve dysfunction. Even with a fractionated course, hearing preservation declined steadily with long-term audiometric follow-up.



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