title: Gamma knife radiosurgery of imaging-diagnosed intracranial meningioma.
abstract: OBJECTIVE
  To evaluate tumor control and outcome from radiosurgery of meningiomas diagnosed by imaging without pathologic verification.
  
  
  METHODS
  A total of 219 meningiomas diagnosed by imaging criteria underwent gamma knife radiosurgery to a median marginal tumor dose of 14 Gy (range 8.9-20), a median treatment volume of 5.0 cm(3) (range 0.47-56.5), and a median maximal dose of 28 Gy (range 22-50). The median follow-up was 29 months (range 2-164).
  
  
  RESULTS
  Tumor progression developed in 7 cases, 2 of which turned out to be different tumors (metastatic nasopharyngeal adenoid cystic carcinoma and chondrosarcoma). One tumor was controlled, but the development of other brain metastases suggested a different diagnosis. The actuarial tumor control rate was 93.2% +/- 2.7% at 5 and 10 years. The actuarial rate of identifying a diagnosis other than meningioma was 2.3% +/- 1.4% at 5 and 10 years. The actuarial rate of developing any postradiosurgical injury reaction was 8.8% +/- 3.0% at 5 and 10 years. No pretreatment variables correlated with tumor control in univariate or multivariate analysis. The risk of postradiosurgery sequelae was lower (5.3% +/- 2.3%) in patients treated after 1991 (with stereotactic MRI and lower doses; p = 0.0104) and tended to increase with treatment volume (p = 0.0537).
  
  
  CONCLUSIONS
  Radiosurgery of meningioma diagnosed by imaging without tissue confirmation is associated with a high rate of tumor control and acceptable morbidity but carries a small risk (2.3%) of an incorrect diagnosis.
authors.affiliation: Department of Radiation Oncology, Center for Image-Guided Neurosurgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. lickinggerjc@msx.upmc.edu
authors.forename: John C
authors.initials: JC
authors.lastname: Flickinger
authors.forename: Douglas
authors.initials: D
authors.lastname: Kondziolka
authors.forename: Ann H
authors.initials: AH
authors.lastname: Maitz
authors.forename: L Dade
authors.initials: LD
authors.lastname: Lunsford
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D003952:Diagnostic Imaging; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008577:Meningeal Neoplasms / Q000175:diagnosis* / Q000601:surgery*; D008579:Meningioma / Q000175:diagnosis* / Q000601:surgery*; D008875:Middle Aged; D016016:Proportional Hazards Models; D016634:Radiosurgery / Q000009:adverse effects; D012189:Retrospective Studies