title: CyberKnife stereotactic radiosurgery for recurrent, metastatic, and residual hemangiopericytomas.
abstract: OBJECTIVE
  Hemangiopericytoma is a rare and aggressive meningeal tumor. Although surgical resection is the standard treatment, hemangiopericytomas often recur with high incidences of metastasis. The purpose of this study was to evaluate the role of CyberKnife stereotactic radiosurgery (CK) in the management of recurrent, metastatic, and residual hemangiopericytomas.
  
  
  METHODS
  In a review of the Stanford radiosurgery database between 2002 and 2009, the authors found 14 patients who underwent CK therapy for recurrent, metastatic, and residual hemangiopericytomas. A total of 24 tumors were treated and the median patient age was 52 years (range 29-70 years) at the time of initial CK therapy. The median follow-up period was 37 months (10-73 months) and all patients had been previously treated with surgical resection. Mean tumor volume was 9.16 cm3 and the mean marginal and maximum radiosurgical doses to the tumors were 21.2 Gy and 26.8 Gy, respectively.
  
  
  RESULTS
  Of the 24 tumors treated, 22 have clinical follow-up data at this time. Of those 22 tumors, 12 decreased in size (54.5%), 6 remained unchanged (27.3%), and 4 showed recurrence (18.2%) after CK therapy. Progression-free survival rate was 95%, 71.5%, and 71.5% at 1, 3, and 5 years after multiple CK treatments. The 5-year survival rate after CK was 81%.
  
  
  CONCLUSIONS
  CK is an effective and safe management option for hemangiopericytomas. The current series demonstrates a tumor control of 81.8%. Other institutions have demonstrated similar outcomes with stereotactic radiosurgery, with tumor control ranging from 46.4% to 100%.
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Anand
authors.initials: A
authors.lastname: Veeravagu
authors.forename: Bowen
authors.initials: B
authors.lastname: Jiang
authors.forename: Chirag G
authors.initials: CG
authors.lastname: Patil
authors.forename: Marco
authors.initials: M
authors.lastname: Lee
authors.forename: Scott G
authors.initials: SG
authors.lastname: Soltys
authors.forename: Iris C
authors.initials: IC
authors.lastname: Gibbs
authors.forename: Steven D
authors.initials: SD
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology / Q000601:surgery*; D018572:Disease-Free Survival; D005260:Female; D006393:Hemangiopericytoma / Q000473:pathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D016896:Treatment Outcome