title: Observation of a dose-control relationship for lung and liver tumors after stereotactic body radiation therapy.
abstract: OBJECTIVE
  To determine prognostic factors for local control of primary or metastatic tumors within the lung or liver treated with stereotactic body radiation therapy (SBRT) within a single institution.
  
  
  METHODS
  The records of 141 consecutive patients with 246 lesions treated with three-fraction SBRT from Oct 1999 through Aug 2005 were reviewed. Local control was assessed radiographically. Univariate and multivariate analyses were performed to evaluate the influence of the following factors on local control: total dose, expressed as either nominal prescription dose or equivalent uniform dose (EUD); gross tumor volume; primary site; treatment site (lung vs. other); histologic characteristics (adenocarcinoma vs. other); gender; age; and primary vs. metastatic tumor.
  
  
  RESULTS
  On univariate analysis, increased dose (either nominal or EUD) and smaller gross tumor volume were significant predictors of higher local control. Lesions treated to a nominal dose of 54 Gy or greater had a 3-year actuarial local control rate of 89.3% compared with 59.0% and 8.1% for those treated to 36-53.9 Gy and less than 36 Gy. On multivariate analysis, only increased nominal dose and EUD retained statistical significance. Treatment was well tolerated; 5.7% of patients experienced Grade 3 or higher toxicity.
  
  
  CONCLUSIONS
  This large single-institution series suggests a dose-control relationship within the range of SBRT doses applied. Excellent local control rates are achieved with a nominal dose of 54 Gy or greater, corresponding to an EUD greater than 65.3 Gy. These results support the use of aggressive SBRT regimens when durable tumor control is the primary objective.
authors.affiliation: Department of Radiation Oncology, University of Colorado Health Sciences Center, Aurora, CO, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: McCammon
authors.forename: Tracey E
authors.initials: TE
authors.lastname: Schefter
authors.forename: Laurie E
authors.initials: LE
authors.lastname: Gaspar
authors.forename: Rebekah
authors.initials: R
authors.lastname: Zaemisch
authors.forename: Daniel
authors.initials: D
authors.lastname: Gravdahl
authors.forename: Brian
authors.initials: B
authors.lastname: Kavanagh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003120:Colorado / Q000453:epidemiology; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000453:epidemiology* / Q000532:radiotherapy*; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009038:Motion; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D015656:Respiratory Mechanics; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D016896:Treatment Outcome