SURG-06. PREOPERATIVE NEOADJUVANT GAMMA KNIFE RADIOSURGERY IN THE TREATMENT OF LARGE BRAIN METASTASIS: AN INITIAL CASE SERIES OF SINGLE INSTITUTE

Abstract

Abstract BACKGROUND Postoperative stereotactic radiosurgery (SRS) following the surgical resection of large brain metastasis is a promising therapeutic option to reduce local recurrence. However, there is an increased risk of radiation necrosis and leptomeningeal spreading and an issue of problematic target delineation. Neoadjuvant SRS, also called preoperative SRS, is an emerging treatment paradigm which delivers radiation in the preoperative setting. An initial series of single-institute cases treated with the neoadjuvant SRS followed by surgical resection of a large BM was reviewed. Method: Between 2019 and 2022, 5 patients underwent neoadjuvant SRS using Gamma Knife radiosurgery (GKS) unit, followed by surgical resection. Local tumor recurrence, distant tumor recurrence, leptomeningeal seeding, and overall survival were investigated. Pathologic findings and surgical gross findings were reviewed. RESULTS The mean age was 59 and 3 patients were female. All patients had multiple lesions, ranged 2 to 7, including a large lesion (mean tumor volume: 29.8 cc). The interval between GKS and surgery was varied between 1 to 14 days. The prescribed dose of plan-to-resect lesion was 12 Gy in four patients and 14 Gy in one patient. All patients underwent gross total resection without surgical complications and had no radiation-induced toxicity. 3 patients were died of extracranial progression during follow-up period, including 1 patient who died before the first follow-up image. Local tumor progression was noted in 1 patient 9 months after treatment. The mean overall survival was 4.5 months although two patients continued to require follow-up. CONCLUSIONS Neoadjuvant SRS may be safe and advantageous for the treatment of BM that require surgical intervention. Long-term investigation with larger patient cohorts and further randomized trials are essential to verify the efficacy of the approach.