ESTRO 2025 - Abstract Book

S671

Clinical - CNS

ESTRO 2025

1440

Mini-Oral International collaboration of neoadjuvant stereotactic radiosurgery for brain metastases: the INTERNEO individual patient data pooled analysis Cristian Udovicich 1 , Kendrick Koo 1,2 , John Michael Bryant 3 , Alejandro Bugarini 4 , Michael Huo 5 , Kyung Hwan Kim 6 , Yuping Derek Li 7 , Daniel E Oliver 3 , Samir Patel 8 , Susanne Rogers 9 , Michael R Chicoine 7,10 , Matthew C Foote 5 , Seon Hwan Kim 6 , Anand Mahadevan 11 , Mark B Pinkham 5 , Joseph Sia 12,2 , Neda Haghighi 12,2,13 1 Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia. 2 Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Australia. 3 Department of Radiation Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, USA. 4 Department of Neurosurgery, Geisinger Health, Danville, USA. 5 Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane, Australia. 6 Department of Neurosurgery, Chungnam National University Hospital, Daejeon, Korea, Republic of. 7 Department of Neurosurgery, Washington University School of Medicine, St Louis, USA. 8 Division of Radiation Oncology, University of Alberta, Edmonton, Canada. 9 Radiation Oncology Center Mittelland, Canton Hospital Aarau, Aarau, Switzerland. 10 Department of Neurosurgery, University of Missouri, Missouri, USA. 11 Department of Radiation Oncology, Perlmutter Cancer Center at New York University Grossman School of Medicine, New York, USA. 12 Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia. 13 Department of Radiation Oncology, Icon Cancer Centre, Richmond, Australia Purpose/Objective: Neoadjuvant stereotactic radiosurgery (NaSRS) is an emerging treatment option for brain metastases (BrM) planned for resection. The aim of this study was to report on the efficacy and safety of NaSRS in an individual patient data pooled analysis. Material/Methods: Patients undergoing single- and multi-fraction NaSRS for BrM at nine institutions in five countries (Australia, Canada, South Korea, Switzerland and USA) were included. Eligibility criteria included BrM from any primary malignancy and no prior local therapy. The primary endpoint was a composite of local recurrence (LR), any grade radionecrosis (RN), and/or nodular leptomeningeal disease (nLMD). Secondary endpoints included these endpoints and Grade ≥2 RN. Endpoints were evaluated using cumulative incidence functions. Results: NaSRS was delivered to 179 patients with 189 BrM. Median follow-up was 28.4 months. Primary malignancies included non-small cell lung carcinoma (44%) and melanoma (17%). The median BrM diameter was 29 mm (IQR 21 36 mm). Single- and multi-fraction NaSRS was utilised in 100 (53%) and 89 BrM (47%) respectively. The median single-fraction dose was 18 Gy (IQR 16-20 Gy). Multi-fraction doses included 24 Gy in three fractions (55%) and 27 Gy in three fractions (25%). The 12-month incidence for the composite endpoint was 8.0%. The 12-month incidence of LR was 4.6%, any grade RN was 3.6%, Grade ≥2 RN was 1.8% and nLMD was 1.2%. Conclusion: Neoadjuvant SRS results in favourable rates of LR, RN and nLMD. We provide a global experience of this treatment approach with the longest median follow-up of neoadjuvant SRS as well as the largest cohort of patients undergoing multi-fraction SRS.

Keywords: brain metastases, preoperative, SRS