title: The Outcome of Hypofractionated Stereotactic Radiosurgery for Large Vestibular Schwannomas.
abstract: OBJECTIVE
  Stereotactic radiosurgery (SRS) for large vestibular schwannomas (VS) remains controversial. We studied the tumor local control and toxicity rates after hypofractionated SRS for VS > 3 cm.
  
  
  METHODS
  A total of 587 patients with VS treated with SRS between 1998 and 2014 were reviewed retrospectively, and 30 Koos grade IV VSs were identified. There were 6 patients with neurofibromatosis 2 (NF2), 8 with cystic tumors, 22 with solid tumors, 19 who underwent primary CyberKnife (CK), and 11 with >3 cm after previous resection. Patients were treated by a median of 3 fractions at 18 Gy.
  
  
  RESULTS
  After a median 97 months, the 3- and 10-year Kaplan-Meier estimates of local control were 85% and 80%, respectively, with 20% requiring salvage treatment. For patients who had previous tumor resection rather than primary CK, the estimates were 46% and 5%, respectively, with progression, and 3-year control rates of 71% and 94% (P = 0.008). Tumor control was also lower among NF2 versus non-NF2 patients (40% vs. 95%; P = 0.0014). Among patients with good clinical baselines before CK, 88% were functionally independent (modified Rankin Scale score, 0-2), 88% had good facial function (House-Brackmann grade I-II), and 38% had serviceable hearing (Gardner-Robertson grade I-II) at last follow-up. Hearing worsening was more likely among patients treated with primary CK (33% vs. 90%; P = 0.04).
  
  
  CONCLUSIONS
  Overall, 80% of large VSs were adequately controlled by CK with 97 months of median follow-up. Patients with previous surgery and NF2 also appeared to have higher rates of tumor progression, and less favorable functional outcomes.
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Mario
authors.initials: M
authors.lastname: Teo
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Li
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Thompson
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Armine T
authors.initials: AT
authors.lastname: Tayag
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Wallach
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Iris C
authors.initials: IC
authors.lastname: Gibbs
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Scott G
authors.initials: SG
authors.lastname: Soltys
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Hancock
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA. Electronic address: sdchang@stanford.edu.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002140:California / Q000453:epidemiology; D015897:Comorbidity; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D034381:Hearing Loss / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D009464:Neuroma, Acoustic / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery*; D015995:Prevalence; D000069473:Radiation Dose Hypofractionation; D016634:Radiosurgery; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome; D055815:Young Adult
keywords: Cystic; Facial nerve; Hearing preservation; Hypo-fractionated stereotactic radiosurgery; Neurofibromatosis; Primary treatment; Vestibular schwannoma