title: Stereotactic radiosurgery of World Health Organization grade II and III intracranial meningiomas: treatment results on the basis of a 22-year experience.
abstract: BACKGROUND
  A study was undertaken to define the variables associated with tumor control and survival after single-session stereotactic radiosurgery (SRS) for patients with atypical and malignant intracranial meningiomas.
  
  
  METHODS
  Fifty patients with World Health Organization (WHO) grade II (n = 37) or grade III (n = 13) meningiomas underwent SRS from 1990 to 2008. Most tumors were located in the falx/parasagittal region or cerebral convexities (n = 35, 70%). Twenty patients (40%) had progressing tumors despite prior external beam radiation therapy (EBRT) (median dose, 54.0 grays [Gy]). The median treatment volume was 14.6 cm(3) ; the median tumor margin dose was 15.0 Gy. Seven patients (14%) received concurrent EBRT (median dose, 50.4 Gy). Follow-up (median, 38 months) was censored at last evaluation (n = 28) or death (n = 22).
  
  
  RESULTS
  Tumor grade correlated with disease-specific survival (DSS) (hazard ratio [HR], 3.4; P = .008), local tumor control (HR, 2.4; P = .02), and progression-free survival (PFS) (HR, 2.6; P = .02) on univariate analysis, but not on multivariate analysis. Multivariate analysis showed that having failed EBRT and tumor volume >14.6 cm(3) were negative predictors of DSS and local control (HR, 3.0; P = .02 and HR, 4.4; P = .01; HR, 3.3; P = .001 and HR, 2.3; P = .02;, respectively). Having failed EBRT was a negative predictor of PFS (HR, 3.5; P = .002). Thirteen patients (26%) had radiation-related complications at a median of 6 months after radiosurgery.
  
  
  CONCLUSIONS
  Tumor progression despite prior EBRT and larger tumor volume are negative predictors of tumor control and survival for patients having SRS for WHO grade II and III intracranial meningiomas.
authors.affiliation: Department of Neurological Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA. pollock.bruce@mayo.edu
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Pollock
authors.forename: Scott L
authors.initials: SL
authors.lastname: Stafford
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Link
authors.forename: Yolanda I
authors.initials: YI
authors.lastname: Garces
authors.forename: Robert L
authors.initials: RL
authors.lastname: Foote
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008577:Meningeal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D008579:Meningioma / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D008875:Middle Aged; D015999:Multivariate Analysis; D060787:Neoplasm Grading; D016634:Radiosurgery; D012189:Retrospective Studies; D016896:Treatment Outcome; D014944:World Health Organization