Factors influencing the outcome of stereotactic radiosurgery in patients with five or more brain metastases

Background Stereotactic radiosurgery (srs) for patients with 5 or more brain metastases (bmets) is a matter of debate. We report our results with that approach and the factors influencing outcome.Methods In the 103 patients who underwent srs for the treatment of 5 or more bmets, primary histology was nonsmall- cell lung cancer (57% of patients). All patients were grouped by Karnofsky performance status and recursive partitioning analysis (rpa) classification. In our cohort, 72% of patients had uncontrolled extracranial disease, and 28% had stable or responding systemic disease. Previous irradiation for 1–4 bmets had been given to 56 patients (54%). The mean number of treated bmets was 7 (range: 5–19), and the median cumulative bmets volume was 2 cm3 (range: 0.06–28 cm3).Results Multivariate analyses showed that stable extracranial disease (p < 0.001) and rpa (p = 0.022) were independent prognostic factors for overall survival (os). Moreover, a cumulative treated bmets volume of less than 6 cm3 (adjusted hazard ratio: 2.54; p = 0.006; 95% confidence interval: 1.30 to 4.99) was associated with better os. The total number of bmets had no effect on survival (p = 0.206). No variable was found to be predictive of local control. The rpa was significant (p = 0.027) in terms of distant recurrence.Conclusions Our study suggests that srs is a reasonable option for the management of patients with 5 or more bmets, especially with a cumulative treatment volume of less than 6 cm3.