Validation of the RTOG recursive partitioning analysis (RPA) classification for brain metastases

Purpose: The Radiation Therapy Oncology Group (RTOG) previously developed t hree prognostic classes for brain metastases using recursive partitioning a nalysis (RPA) of a large database, These classes were based on Karnofsky pe rformance status (KPS), primary tumor status, presence of extracranial syst em metastases, and age, An analysis of RTOG 91-04, a randomized study compa ring two dose-fractionation schemes with a comparison to the established RT OG database, was considered important to validate the RPA classes. Methods and Materials: A total of 445 patients were randomized on RTOG 91-0 4, a Phase III study of accelerated hyperfractionation versus accelerated f ractionation, No difference was observed between the two treatment arms wit h respect to survival. Four hundred thirty-two patients were included in th is 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 t hree classes, but only patients in RPA Classes I and II were eligible for R TOG 91-04. Results: For RPA Class I, the median survival time was 6.2 months and 7.1 m onths 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, respective ly (p = 0.22). Conclusion: This analysis indicates that the RPA classes are valid and reli able for historical comparisons, Both the RTOG and other clinical trial org anizers should currently utilize this RPA classification as a stratificatio n factor for clinical trials. (C) 2000 Elsevier Science Inc.