title: A retrospective analysis of tumor volumetric responses to five-fraction stereotactic radiotherapy for paragangliomas of the head and neck (glomus tumors).
abstract: BACKGROUND
  Skull base paragangliomas (SBP) are locally expansile tumors that can be treated with stereotactic radiotherapy with favorable results. This report describes the results of 31 patients with SBP treated with CyberKnife radiotherapy delivering a total dose of 25 Gray in five fractions.
  
  
  METHODS
  All patients treated with five-fraction CyberKnife radiotherapy at a single institution were identified between 2007 and 2013. Tumor volumetric analyses were performed to assess responses to radiotherapy.
  
  
  RESULTS
  Median follow-up was 24 months with a range of 4-78 months. Local control and overall survival were 100%. Of the 20 patients who presented with tinnitus, 12 reported improvement (60%), of whom 6 reported complete resolution. There was a 37.3% reduction in tumor volume among all patients (p = 0.16). On subset analysis of patients with ≥24 months of follow-up, tumor volume decreased 49% (p = 0.01). The rate of grade 1-2 toxicity was 19%, with no grade 3 or worse toxicity.
  
  
  CONCLUSIONS
  A five-fraction CyberKnife-based stereotactic radiotherapy approach is safe and efficacious for the management for patients with SBP. Our findings suggest the potential use of this strategy as a definitive or salvage treatment option for SBP.
authors.affiliation: Department of Radiation Oncology, Harold C. Simmons Cancer Center, University of Texas at Southwestern Medical Center, Dallas, Tex., USA.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Chun
authors.forename: Lucien A
authors.initials: LA
authors.lastname: Nedzi
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Choe
authors.forename: Ramzi E
authors.initials: RE
authors.lastname: Abdulrahman
authors.forename: Susie A
authors.initials: SA
authors.lastname: Chen
authors.forename: John S
authors.initials: JS
authors.lastname: Yordy
authors.forename: Robert D
authors.initials: RD
authors.lastname: Timmerman
authors.forename: Joe W
authors.initials: JW
authors.lastname: Kutz
authors.forename: Brandon
authors.initials: B
authors.lastname: Isaacson
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005918:Glomus Tumor / Q000175:diagnosis / Q000601:surgery*; D006258:Head and Neck Neoplasms / Q000175:diagnosis / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010235:Paraganglioma / Q000175:diagnosis / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome; D047368:Tumor Burden; D055815:Young Adult