Stereotactic radiosurgery for the treatment of brain metastases: impact of cerebral disease burden on survival

Abstract

Stereotactic radiosurgery (SRS) for brain metastases has been carried out at the Leeds Gamma Knife Centre since March 2009. The aim of this study was to examine the outcomes and toxicity in our initial cohort of patients. The medical records of patients with brain metastases referred to the Leeds Gamma Knife Centre between March 2009 and July 2010 were retrospectively reviewed. Data on survival, primary tumour, Karnofsky performance status, time from diagnosis to identification of brain metastases, previous treatment for brain metastases and results of staging prior to SRS were recorded. Patients were followed up with regular magnetic resonance imaging of the brain for a minimum of 6 months and data on toxicity and oral steroid dose were recorded. Statistical analysis was carried out using SPSS v14.0. Survival curves were compared using the Log Rank test. Fifty eight patients (19 male) had a median survival of 50.4 weeks (95% CI, 32.6-68.2 weeks). Lung (36%) and breast (27%) were the most common primary tumours. Patients with a total volume of metastases treated < 5000 mm(3) (p = 0.007) or between 5000 mm(3) and 10,000 mm(3) (p = 0.01) had significantly improved survival compared with patients with a total treated volume > 10,000 mm(3). In addition, largest treated lesion < 5000 mm(3) was a positive prognostic factor. Patients with a single metastasis did not survive significantly longer than those with multiple metastases. Steroid dose dropped significantly after SRS (p < 0.01) and was the same or less in 91% of patients. There were only three cases of grade 3 toxicity. Our study reports survival comparable with other series on radiosurgery and demonstrates a significant decrease in steroid dose following treatment. It also shows that the size of the largest treated metastasis and total volume of metastatic disease seemed a better predictor of outcome than number of metastases treated.