Neoadjuvant Gamma Knife Surgery for Metastatic Brain Tumor: Clinical Use and Impact on Leptomeningeal Seeding

Purpose This study aimed to compare leptomeningeal seeding (LMS) incidence, local failure rates, and survival outcomes between neoadjuvant and adjuvant gamma knife surgery (GKS) in patients with brain metastases. Methods We retrospectively analyzed 120 patients treated at a single institution from 2008 to 2022. Overall survival (OS), progression‑free survival (PFS), LMS occurrence, local failure, and key clinical prognostic variables were compared between the neoadjuvant and adjuvant GKS groups. Results Seventy patients received neoadjuvant GKS, while 50 received adjuvant GKS. Baseline differences in primary tumor origin, preoperative Karnofsky Performance Score, and extracranial metastasis were statistically significant. No significant differences were observed in OS (p = 0.21), PFS (p = 0.27), radiation induced edema (p = 0.219) or local failure (p = 0.19) between groups. LMS incidence was significantly lower in the neoadjuvant group (p = 0.043), with this advantage maintained after propensity score matching (p = 0.046). Conclusions Neoadjuvant GKS yields survival and local failure outcomes comparable to adjuvant GKS, while significantly reducing the risk of LMS. These findings support the potential clinical advantage of neoadjuvant GKS in the management of brain metastases.