title: Prior surgical intervention and tumor size impact clinical outcome after precision radiotherapy for the treatment of optic nerve sheath meningiomas (ONSM).
abstract: OBJECTIVE
  We analyzed our long-term experience with fractionated stereotactic radiotherapy (FSRT) in patients with meningioma of the optic nerve sheath (ONSM).
  
  
  METHODS
  Between January 1991 and January 2010, 40 patients with ONSM were treated using FSRT. Of these, 19 patients received radiotherapy as primary treatment, and 21 patients were treated after surgical resection. The median target volume was 9.2 ml, median total dose was 54 Gy in median single fractions of 1,8 Gy.
  
  
  RESULTS
  Local progression-free survival was 100%. Median survival after FSRT was 60 months (range 4-228 months). In all patients overall toleration of FSRT was very good. Acute toxicity was mild. Prior to RT, 29 patients complained about any kind of visual impairment including visual field deficits, diplopia or amaurosis. Prior surgical resection was identified as a negative prognostic factor for visual outcome, whereas patients with larger tumor volumes demonstrated a higher number of patients with improvement of pre-existing visual deficits.
  
  
  CONCLUSIONS
  Long-term outcome after FSRT for ONSM shows improved vision in patients not treated surgically prior to RT; moreover, the best improvement of visual deficits are observed in patients with larger target volumes. The absence of tumor recurrences supports that FSRT is a strong alternative to surgical resection especially in small tumors without extensive compression of normal tissue structures.
authors.affiliation: Department of Radiation Oncology, University Hospital of Heidelberg, Im Neuenheimer Feld 400, Heidelberg, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Adeberg
authors.forename: Thomas
authors.initials: T
authors.lastname: Welzel
authors.forename: Stefan
authors.initials: S
authors.lastname: Rieken
authors.forename: Jürgen
authors.initials: J
authors.lastname: Debus
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Combs
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018572:Disease-Free Survival; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008495:Medical Oncology / Q000379:methods; D008577:Meningeal Neoplasms / Q000532:radiotherapy* / Q000601:surgery*; D008579:Meningioma / Q000532:radiotherapy* / Q000601:surgery*; D008875:Middle Aged; D009900:Optic Nerve / Q000473:pathology*; D019574:Optic Nerve Neoplasms / Q000532:radiotherapy* / Q000601:surgery*; D011379:Prognosis; D011878:Radiotherapy / Q000379:methods; D016896:Treatment Outcome