Radiosurgery for treatment of brain metastases: estimation of patient eligibility using three stratification systems

Abstract

Purpose: To compare three patient stratification systems predicting survival: recursive partitioning analysis (RPA), score index for radiosurgery in brain metastases (SIR), and a proposed basic score for brain metastases (BS-BM).

Methods and materials: We analyzed the outcome of 110 patients treated with Leksell Gamma Knife radiosurgery between December 1999 and January 2003. The BS-BM was calculated by evaluating three main prognostic factors: Karnofsky performance status, primary tumor control, and presence of extracranial metastases.

Results: The median survival was 27.6 months for RPA Class I, 10.7 months for RPA Class II, and 2.8 months for RPA Class III (p <0.0001). Using the SIR, the median survival was 27.7, 10.8, 4.6, and 2.4 months for a score of 8-10, 5-7, 4, and 0-3, respectively (p <0.0001). The median survival was undefined in patients with a BS-BM of 3 (55% at 32 months) and was 13.1 months for a BS-BM of 2, 3.3 months for a BS-BM of 1, and 1.9 months for a BS-BM of 0 (p <0.0001). The backward elimination model in multivariate Cox analysis identified SIR and BS-BM as the only two variables significantly associated with survival (p = 0.031 and p = 0.043, respectively).

Conclusion: SIR and BS-BM were the most accurate for estimating survival. They were specific enough to identify patients with short survival (SIR 0-3 and BS-BM 0). Because of it simplicity, BS-BM is easier to use.