Recursive partitioning analysis classifications I and II: Applicability evaluated in a randomized trial for resected single brain metastases

Purpose: Radiation Therapy Oncology Group (RTOG) recursive partitioning analysis (RPA) prognostic classes I and II for patients with brain metastases is derived from a database made up primarily of patients with unresected and multiple metastases. An analysis of a previously published randomized trial was performed to determine the applicability of these RPA prognostic classes in the setting of resection of single metastases to the brain. Patients and Methods: Ninety-five patients with single metastases to the brain that were treated with complete surgical resection entered this study. Patients were randomly assigned to treatment with postoperative whole brain radiotherapy (WBRT) (n = 49 patients) or no further brain treatment (n = 46 patients). All patients entered on this study had a Karnofsky performance status of ≥70. Therefore, although the RTOG RPA has 3 classes, only patients with RPA classes I (n = 26) or II (n = 69) were eligible for this study analysis. Results: For RPA class I, the median survival was 10.9 months versus 9.8 months for class II patients (P = 0.45). Multivariate analysis showed that only postoperative WBRT, independent of RPA class I or II, lessened the risk of brain tumor recurrence (P < 0.0001). Conclusion: This analysis of a randomized trial evaluating postoperative WBRT in the treatment of single metastases to the brain showed no difference in survival between RPA class I or II patients. In addition, the use of postoperative WBRT after complete surgical resection of single brain metastases results in substantially better control of disease in the brain independent of RPA classes I or II.