Preoperative Versus Postoperative Radiosurgery of Brain Metastases: A Meta-Analysis

Objective: While postoperative resection cavity radiosurgery (post-SRS) is an accepted treatment paradigm for brain metastasis (BM) patients who undergo surgical resection, there is emerging interest in preoperative radiosurgery (pre-SRS) followed by surgical resection as an alternative treatment paradigm. Here, we performed a meta-analysis of the available literature on this matter. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a search of all studies evaluating pre-SRS and post-SRS was completed. Local recurrence (LR), overall survival (OS), radiation necrosis (RN), and leptomeningeal disease (LMD) were evaluated from the available data. Moderator analysis and pooled effect sizes were performed using a proportional meta-analysis with R using the metafor package. Statistics are presented as mean [95% confidence interval]. Results: We identified 6 pre-SRS and 33 post-SRS studies with comparable tumor volume (4.5–17.6 cm³). There were significant differences in the pooled estimates of LR and LMD, favoring pre-SRS over post-SRS. Pooled aggregate for LR was 11.0% [4.9–13.7] and 17.5% [15.1–19.9] for pre- and post-SRS studies (P = 0.014). Similarly, pooled estimates of LMD favored pre-SRS, 4.4% [2.6–6.2], relative to post-SRS, 12.3% [8.9–15.7] (P = 0.019). In contrast, no significant differences were found in terms of RN and OS. Pooled estimates for RN were 6.4% [3.1–9.6] and 8.9% [6.3–11.6] for pre- and post-SRS studies (P = 0.393), respectively. Pooled estimates for OS were 60.2% [55.8–64.6] and 60.5% [56.9–64.0] for pre- and post-SRS studies (P = 0.974). Conclusions: This meta-analysis supports further exploration of pre-SRS as a strategy for the treatment of BM.