ESTRO 2025 - Abstract Book

S721

Clinical - CNS

ESTRO 2025

Results: The primary cohort of 193 patients underwent 307 SRS sessions for 1350 BM imaged with the dual sequences while the control cohort consisted of 86 patients who underwent 137 SRS sessions for 455 BM imaged with MPRAGE alone. The median number of treated BM per session (3, Range: 1-31 vs. 2, Range: 1-30, p<0.001) was significantly higher in the primary cohort due to improved lesion detection sensitivity of the 3D-TSE sequence. Cohorts were well-balanced regarding age, Karnofsky performance status, primary disease site, first course of SRS, type of systemic therapy, and status of extracranial disease. At the time of analysis, 52.3% (232/444) of sessions resulted in a distant intracranial failure (DIF), followed by a NCDI in the primary vs. control cohorts (46.6% vs. 65.0%, p<0.001). Time to NCDI was significantly longer in the primary cohort compared to control cohort, 12.4 vs. 8.1 months, p=0.004. A total of 232 NCDIs were recorded across both cohorts, 81.0% managed with SRS and 19.0% with whole brain radiotherapy (WBRT) or intrathecal/systemic therapy alone. Prevalence of NCDI techniques differed significantly between cohorts; the primary cohort had a higher proportion of salvage WBRT compared to the control cohort (23.1% vs. 12.4%, p=0.043). Number of treated lesions (HR:1.054, p<0.001), dual sequence imaging (HR:0.635, p=0.002), undergoing first course of SRS (HR:0.727, p=0.033), and controlled extracranial disease (HR:0.726, p=0.048) remained significant in multivariate cox-regression analysis for NCDI. Conclusion: Adding 3D-TSE to MPRAGE image sequence at the time of SRS prolongs time to next CNS-directed intervention demonstrating its clinical value. These findings endorse routine incorporation of T1 post-contrast 3D-TSE into SRS protocols for a patient-centric management of BM. Digital Poster Analysis of radiotherapy in intermediate and high-risk meningiomas : outcomes and prognostic factors Ji Sang Kim 1 , So Jung Lee 2 , Jin Ho Song 1 , Seok Hyun Son 1 1 Radiation oncology, Seoul St. Mary’s Hospital, Seoul, Korea, Republic of. 2 Radiation oncology, Incheon St. Mary’s Hospital, Incheon, Korea, Republic of Purpose/Objective: This study aimed to investigate treatment outcomes and identify prognostic factors for progression-free survival (PFS) in patients with intermediate-high risk meningiomas who underwent adjuvant or salvage aim of radiotherapy. Material/Methods: We retrospectively reviewed the data of 61 patients with intermediate-high risk meningiomas who underwent adjuvant or salvage aim of radiotherapy. All patients included in this study were diagnosed with meningioma pathologically through surgical resection. Intermediate-risk patients were those with a recurrent World Health Organization (WHO) grade 1 meningioma, or WHO grade 2 of gross total resection. High-risk patients were those with a WHO grade 2 with subtotal resection or recurrent WHO grade II, or new or recurrent WHO grade III with any resection extent. Fractionated radiotherapy (FSRT) was performed in a range of 50.4-60 Gy in 28-31 fractions, and stereotactic radiosurgery (SRS) was performed in a range of 12-22 Gy. Results: Median follow-up duration was 48.1 months (range, 3.1-202.4 months). Twelve intermediate-risk and 49 high-risk meningiomas were included in this study. FSRT and SRS were performed on 43 and 18 patients with meningioma. The 3-yr and 5-yr PFS were 86.4% and 76%, respectively. High-risk meningiomas showed adverse PFS than intermediate-risk meningiomas without statistical significance (53.0% vs. 80.2%, p=0.1). WHO grade 3 meningioma showed distinct lower PFS than WHO grade 1-2 ( 50.0% vs. 60.6%, p=0.1). Recurrent meningioma showed statistically Keywords: 3D-TSE, SRS, distant intracranial control 3261