Preoperative versus postoperative stereotactic radiosurgery for brain metastases: a systematic review and meta-analysis of comparative studies.

Resection is often the primary treatment for large brain tumors but is less practical for multiple brain metastases (BM). Current guidelines recommend stereotactic radiosurgery (SRS) for untreated BMs or following the surgical removal of a solitary BM to reduce the risk of local tumor recurrence. Preoperative SRS (pre-SRS) shows promise with fewer complications and more precise targeting, but it lacks tissue diagnosis and may hinder wound healing. This study aims to compare the safety and efficacy of pre-SRS and postoperative SRS (post-SRS) for BM treatment. A comprehensive literature search was conducted in PubMed, Embase, Scopus, and Cochrane Library. Studies were selected based on PICO criteria, including patients with metastatic intracranial lesions undergoing preoperative or postoperative radiosurgery. Data related to outcomes and complications were extracted. Meta-analysis was performed, employing the fixed effect model due to study design similarities and limited patient numbers. Four studies encompassing 616 BM patients (221 preoperative, 405 postoperative) were included. Patient characteristics, including age, gender, cancer source, and lesion location, were similar between groups. Radiosurgery modalities included LINAC and Gamma Knife, with hypofractionated treatments more common postoperatively. Outcomes showed comparable overall survival (p = 0.07), local failure (p = 0.26), and distant failure rates (p = 0.84) between groups. The preoperative group had lower risks of radiation necrosis (p = 0.02) and leptomeningeal disease (p = 0.03) in 1-year follow-up, with significantly better composite outcomes (p = 0.04). No significant difference in wound issues was observed (p = 0.98). This review reveals pre- and post-SRS for BM have similar outcomes for LF, DF, and OS. Pre-SRS potentially lowers RN and LMD risks, with better tumor targeting and less radiation to healthy tissue, while post-SRS targets residual disease but with higher complication risks. Future research should optimize SRS protocols.