title: Validation of the RTOG recursive partitioning analysis (RPA) classification for brain metastases.
abstract: OBJECTIVE
  The Radiation Therapy Oncology Group (RTOG) previously developed three prognostic classes for brain metastases using recursive partitioning analysis (RPA) of a large database. These classes were based on Karnofsky performance status (KPS), primary tumor status, presence of extracranial system metastases, and age. An analysis of RTOG 91-04, a randomized study comparing two dose-fractionation schemes with a comparison to the established RTOG database, was considered important to validate the RPA classes.
  
  
  METHODS
  A total of 445 patients were randomized on RTOG 91-04, a Phase III study of accelerated hyperfractionation versus accelerated fractionation. No difference was observed between the two treatment arms with respect to survival. Four hundred thirty-two patients were included in this analysis. The majority of the patients were under age 65, had KPS 70-80, primary tumor controlled, and brain-only metastases. The initial RPA had three classes, but only patients in RPA Classes I and II were eligible for RTOG 91-04.
  
  
  RESULTS
  For RPA Class I, the median survival time was 6. 2 months and 7.1 months for 91-04 and the database, respectively. The 1-year survival was 29% for 91-04 versus 32% for the database. There was no significant difference in the two survival distributions (p = 0.72). For RPA Class II, the median survival time was 3.8 months for 91-04 versus 4.2 months for the database. The 1-year survival was 12% and 16% for 91-04 and the database, respectively (p = 0.22).
  
  
  CONCLUSIONS
  This analysis indicates that the RPA classes are valid and reliable for historical comparisons. Both the RTOG and other clinical trial organizers should currently utilize this RPA classification as a stratification factor for clinical trials.
authors.affiliation: University of Colorado Health Science Center, Denver, CO, USA. laurie.gaspar@uchsc.edu
authors.forename: L E
authors.initials: LE
authors.lastname: Gaspar
authors.forename: C
authors.initials: C
authors.lastname: Scott
authors.forename: K
authors.initials: K
authors.lastname: Murray
authors.forename: W
authors.initials: W
authors.lastname: Curran
mesh_terms: D000367:Age Factors; D000368:Aged; D001932:Brain Neoplasms / Q000145:classification* / Q000532:radiotherapy / Q000556:secondary; D019583:Dose Fractionation, Radiation; D006801:Humans; D017567:Karnofsky Performance Status; D008875:Middle Aged; D015203:Reproducibility of Results; D016019:Survival Analysis