ESTRO 2025 - Abstract Book

S764

Clinical - CNS

ESTRO 2025

4432

Digital Poster Prognostic Validation of Brain Metastasis Velocity Metrics: Insights from a large Single-Institution Cohort Study Lea Horne 1 , Coralia Dehelean 1 , Sebastian Hubertus Maier 1 , Alexander Nitschmann 1 , Daniel Felix Fleischmann 1,2 , Niklas Oberwegner 3 , Maximilian Niyazi 1,4,5 , Raphael Bodensohn 1,4,5 , Stefanie Corradini 1 , Claus Belka 1,2,6 , Stephan Schönecker 1,6 , Sebastian Norbert Marschner 1,2 1 Department of Radiation Oncology, University Hospital LMU Munich, Munich, Germany. 2 German Cancer Consortium (DKTK) Partner Site Munich, German Cancer Research Center (DKFZ), Heidelberg, Germany. 3 School of Management, Technical University of Munich, Munich, Germany. 4 Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany. 5 German Cancer Consortium (DKTK), partner site Tübingen, German Cancer Research Center (DKFZ), Heidelberg, Germany. 6 Bavarian Cancer Research Center (BZKF), Bavarian Cancer Research Center (BZKF), Munich, Germany Purpose/Objective: Brain metastases represent a significant clinical challenge, with approximately 10–40% of patients with solid tumors affected. Prognostic tools such as cumulative brain metastasis velocity (cBMV), volumetric brain metastasis velocity (vBMV), initial brain metastasis velocity (iBMV) and Diagnosis-Specific Graded Prognostic Assessment (DS-GPA) have been proposed to predict survival and guide treatment strategies. In this retrospective analysis, we evaluated the applicability and validity of these metrics in a large cohort of patients treated at our institution. Material/Methods: Patients treated with repeated courses of stereotactic radiosurgery (SRS), hypofractionated SRS (HFSRT), or whole brain radiation therapy (WBRT) in our department between 2018 and 2024 were retrospectively included. Prognostic metrics, including cBMV, vBMV, iBMV, and DS-GPA, were evaluated for overall survival (OS), intracranial progression-free survival (iPFS), and WBRT-free survival (WBFS) using Kaplan-Meier curves, competing risks regression, and Cox proportional hazards models. Harrell’s C-index was calculated to assess predictive accuracy. Results: 122 Patients with 817 metastases were retrospectively analyzed. Median number of radiotherapy courses per patient was 2 (range: 2-6). cBMV was a robust predictor of OS (p <0.001), iPFS (p<0.001), and WBFS(p <0.001), with higher cBMV values consistently associated with significantly shorter survival times. Patients with cBMV1 of <4 metastases/year had a median OS of 35.4 months compared to 16.2 and 13.3 months in the 4–13 and >13 metastases/year groups, respectively. vBMV also demonstrated significant associations with OS (p<0.001), iPFS (p=0.001), and WFS (p=0.009). iBMV demonstrated no significant association with survival outcomes, including OS (p=0.752), iPFS (p=0.972), and WBFS (p=0.76). DS-GPA correlated with OS in grouped analyses, but its Harrell’s C index was 0.552 compared to 0.742 for cBMV2. Conclusion: This study underlines the prognostic significance of cBMV and vBMV in predicting survival outcomes for patients with brain metastases, establishing their utility as reliable tools for risk stratification. In contrast, iBMV showed no significant association with survival outcomes, and DS-GPA, while correlating with OS, demonstrated lower predictive accuracy (Harrell’s C-index: 0.552). These findings highlight the necessity of constantly refining and validating prognostic metrics to enhance their clinical applicability and support tailored treatment approaches in the management of brain metastases.

Keywords: Brain metastases, SRS, brain metastases velocity