title: Stereotactic body radiation therapy in spinal metastases.
abstract: OBJECTIVE
  Based on reports of safety and efficacy, stereotactic body radiotherapy (SBRT) for treatment of malignant spinal tumors was initiated at our institution. We report prospective results of this population at Mayo Clinic.
  
  
  METHODS
  Between April 2008 and December 2010, 85 lesions in 66 patients were treated with SBRT for spinal metastases. Twenty-two lesions (25.8%) were treated for recurrence after prior radiotherapy (RT). The mean age of patients was 56.8 ± 13.4 years. Patients were treated to a median dose of 24 Gy (range, 10-40 Gy) in a median of three fractions (range, 1-5). Radiation was delivered with intensity-modulated radiotherapy (IMRT) and prescribed to cover 80% of the planning target volume (PTV) with organs at risk such as the spinal cord taking priority over PTV coverage.
  
  
  RESULTS
  Tumor sites included 48, 22, 12, and 3 in the thoracic, lumbar, cervical, and sacral spine, respectively. The mean actuarial survival at 12 months was 52.2%. A total of 7 patients had both local and marginal failure, 1 patient experienced marginal but not local failure, and 1 patient had local failure only. Actuarial local control at 1 year was 83.3% and 91.2% in patients with and without prior RT. The median dose delivered to patients who experienced local/marginal failure was 24 Gy (range, 18-30 Gy) in a median of three fractions (range, 1-5). No cases of Grade 4 toxicity were reported. In 1 of 2 patients experiencing Grade 3 toxicity, SBRT was given after previous radiation.
  
  
  CONCLUSIONS
  The results indicate SBRT to be an effective measure to achieve local control in spinal metastases. Toxicity of treatment was rare, including those previously irradiated. Our results appear comparable to previous reports analyzing spine SBRT. Further research is needed to determine optimum dose and fractionation to further improve local control and prevent toxicity.
authors.affiliation: Mayo Medical School, College of Medicine, Mayo Clinic, Rochester, MN, USA.
authors.forename: Kamran A
authors.initials: KA
authors.lastname: Ahmed
authors.forename: Michael C
authors.initials: MC
authors.lastname: Stauder
authors.forename: Robert C
authors.initials: RC
authors.lastname: Miller
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Bauer
authors.forename: Peter S
authors.initials: PS
authors.lastname: Rose
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Olivier
authors.forename: Paul D
authors.initials: PD
authors.lastname: Brown
authors.forename: Debra H
authors.initials: DH
authors.lastname: Brinkmann
authors.forename: Nadia N
authors.initials: NN
authors.lastname: Laack
mesh_terms: D000368:Aged; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000532:radiotherapy / Q000601:surgery*; D058958:Organs at Risk; D011446:Prospective Studies; D011788:Quality of Life; D016634:Radiosurgery / Q000379:methods* / Q000401:mortality; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D013116:Spinal Cord; D013125:Spinal Neoplasms / Q000401:mortality / Q000532:radiotherapy / Q000556:secondary* / Q000601:surgery*; D015996:Survival Rate