Validating the SIR: a better prognostic score index for patients with brain metastases treated with stereotactic radiosurgery

Abstract

Objective: The aim of this paper is to validate the score index forsurvival in patients treated with stereotactic radiosurgery, using aclassification prepared to better evaluate the prognosis of patientswith brain metastasis submitted to stereotactic surgery, re-evaluatingsurvival of patients and reviewing the medical literature. Methods:Data from 100 patients with brain metastases treated with stereotacticradiosurgery at a single institution, between July 1993 and February2000, were retrospectively analyzed. The prognostic factors andscores studied were age, Karnofsky performance status, extracranialdisease status, number of brain lesions, volume of the largest lesion,primary tumor type, treated or not with whole brain radiation therapy,SIR, and RPA. Kaplan-Meier actuarial survival curves for subsets werecalculated and compared by log-rank test. Complete and backwardelimination Cox models were utilized to identify the prognostic factorsand scores independently associated with survival. Results: Karnofskyperformance status, extracranial disease status, volume of the largestbrain lesion, RPA, and SIR were significantly correlated with prognosisin Kaplan-Meier survival analysis. Applying Cox models, significancewas observed for KPS and volume of the largest lesion (p < 0.0001and p = 0.0182, respectively), as well as for SIR and RPA when testedindividually (p < 0.0001 and p = 0.0002, respectively). However, whentesting SIR and RPA together, only SIR reached independent statisticalsignificance (p < 0.0001). Conclusion: SIR classification demonstrateda better accuracy in predicting survival time than RPA. SIR was testedin other centers, showing superior accuracy and applicability than theRPA, thus validating this score