title: Recursive partitioning analysis for the prediction of stereotactic radiosurgery brain metastases lesion control.
abstract: OBJECTIVE
  The objective of this investigation was to identify independent pretreatment factors that predict for control of local brain metastases (BM) in a large single-institution series of patients receiving stereotactic radiosurgery (SRS). Recursive partitioning analysis was used to potentially identify a class of patients with durable lesion control characteristics.
  
  
  METHODS
  A retrospective SRS database containing baseline characteristics, treatment details, and follow-up data of newly diagnosed patients with 1-3 BM (on magnetic resonance imaging) treated with linear accelerator-based SRS was created. Three study endpoints were used: time to progression (primary endpoint, individual lesion progression; n = 536), time to first progression (secondary endpoint, first lesion progression on an individual patient basis; n = 380), and overall survival (secondary endpoint; n = 380). Recursive partitioning analysis (RPA) was performed to identify predictors of time to progression.
  
  
  RESULTS
  Multivariable analysis demonstrated that lesion aspect/phenotype and radiotherapy schedule were independent factors associated with both progression outcomes. Presence of tumor necrosis was found to be associated with a significant hazard of progression (hazard ratio >3), whereas use of the most intense radiotherapy fractionation schedule (21 Gy in one fraction) was associated with significant reductions in progression (hazard ratio <0.3). RPA using SRS dose and lesion aspect/phenotype was created and described three distinct prognostic groups.
  
  
  CONCLUSIONS
  RPA of a large retrospective database of patients receiving SRS confirmed previous observations regarding the importance of SRS dose and lesion aspect/phenotype in lesion control and overall survival. The SRS lesion analysis may help to stratify future clinical trials and better define patient care options and prognosis.
authors: Department of Radiation Oncology, London Regional Cancer Program, London Health Sciences Centre, London, Ontario, Canada. george.rodrigues@lhsc.on.ca
authors: George
authors: G
authors: Rodrigues
authors: Jaap
authors: J
authors: Zindler
authors: Andrew
authors: A
authors: Warner
authors: Frank
authors: F
authors: Lagerwaard
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000556:secondary* / Q000601:surgery*; D018450:Disease Progression; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult