title: Stereotactic interstitial radiosurgery with the Photon Radiosurgery System (PRS) for metastatic brain tumors: a prospective single-center clinical trial.
abstract: OBJECTIVE
  To evaluate the efficacy and the treatment outcome of tumor patients being treated stereotactically with a miniature X-ray generator (Photon Radiosurgery System, PRS).
  
  
  METHODS
  Thirty-five patients with histologically diagnosed cerebral metastases were treated with a single fraction of stereotactic interstitial irradiation (median, 18 Gy). Clinical and neuroimaging evaluation were assessed at 2-, 6-, and 12-week intervals postoperatively and every 3 months thereafter. Survival, local control, and distant and overall brain freedom from progression were obtained using the Kaplan-Meier method.
  
  
  RESULTS
  Median survival was 7.37 months and the actuarial survival rates at 6 and 12 months were 60.0% and 34.3%, respectively. Acute complications on six patients were associated with shorter survival. Local tumor control at the initial stage and at the last follow-up were 82% and 50%. Eighteen patients (53%) developed distant brain metastases after treatment. At 1 year, the local control rate and distant and overall brain freedom from progression were 33.0%, 43.3%, and 14.7%, respectively. A shorter local tumor control was observed by PRS treatment of a recurrent tumor and by irregular tumor configuration.
  
  
  CONCLUSIONS
  Interstitial radiosurgery with the PRS requires continued investigation. It allows for an immediate and potentially cost-efficient treatment for patients with singular, small (<or= 6.36 cm(3); or <or= 2.3 cm) spherical brain metastasis subsequent to a stereotactic biopsy.
authors.affiliation: Institute of Brain Research, University of Tuebingen, Tuebingen, Germany. georgios.pantazis@med.uni-tuebingen.de
authors.forename: Georgios
authors.initials: G
authors.lastname: Pantazis
authors.forename: Michael
authors.initials: M
authors.lastname: Trippel
authors.forename: Walter
authors.initials: W
authors.lastname: Birg
authors.forename: Christoph B
authors.initials: CB
authors.lastname: Ostertag
authors.forename: Guido
authors.initials: G
authors.lastname: Nikkhah
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000647:Amnesia / Q000209:etiology; D001932:Brain Neoplasms / Q000401:mortality / Q000556:secondary / Q000601:surgery*; D018450:Disease Progression; D004867:Equipment Design; D005260:Female; D020233:Gait Disorders, Neurologic / Q000209:etiology; D006801:Humans; D017567:Karnofsky Performance Status; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010291:Paresis / Q000209:etiology; D017785:Photons / Q000627:therapeutic use*; D011446:Prospective Studies; D016634:Radiosurgery / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D011879:Radiotherapy Dosage; D012074:Remission Induction; D016879:Salvage Therapy / Q000379:methods; D015996:Survival Rate; D014057:Tomography, X-Ray Computed