Background: Brain metastases are the most common intracranial tumours. Variation exists in the use of stereotactic radiosurgery for patients with 10 or more brain metastases. Concerns include an increasing number of brain metastases being associated with poor survival, the lack of prospective, randomised data and an increased risk of toxicity.
Methods: We performed a systematic review and meta-analysis to assess overall survival of patients with ten or more brain metastases treated with stereotactic radiosurgery as primary therapy. The search strings were applied to MEDLINE, Embase and the Cochrane Central Register of Controlled Trials (CENTRAL). Log hazard ratios and standard errors were estimated from each included study. A random-effects meta-analysis using the DerSimonian and Laird method was applied using the derived log hazard ratios and standard errors on studies which included a control group.
Results: 15 studies were included for systematic review. 12 studies were used for pooled analysis for overall survival at set time points, with a predicted 12 month survival of 20-40%. The random-effects meta-analysis in five studies of overall survival comparing ten or greater metastases against control showed statistically worse overall survival in the 10 + metastases group (1.10, 95% confidence interval 1.03-1.18, p-value = < 0.01, I2 = 6%). A funnel plot showed no evidence of bias. There was insufficient information for a meta-analysis of toxicity.
Discussion: Overall survival outcomes of patients with ten or more brain metastases treated with SRS is acceptable and should not be a deterrent for its use. There is a lack of prospective data and insufficient real-world data to draw conclusions on toxicity.
Prospero id: CRD42021246115.
Keywords: Multiple metastases; Radiotherapy; Stereotactic radiosurgery.
This systematic review and meta-analysis is the first of its kind in the literature and provides information on overall survival outcomes and toxicities encountered in patients with ten or more brain metastases treated with stereotactic radiosurgery. Centres treating patients with ten or more brain metastases are doing so based only on retrospective real-world data analyses, the vast majority of which are from single centres and single radiotherapy platforms. This review provides an additional evidence resource for practitioners of stereotactic radiosurgery to aide in the management of this difficult patient group. The methods used to predict survival outcomes through the calculation of log hazard ratios and standard errors allowed analysis of small, retrospective case series. To our knowledge, this is the first meta-analysis of this patient group gives evidence for acceptable overall survival outcomes post-treatment, and provides further evidence for the use of stereotactic radiosurgery for these patients.Overall survival following stereotactic radiosurgery for ten or more brain metastases: a systematic review and meta-analysis.
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