S279
Clinical - Breast
ESTRO 2026
Digital Poster 2517
respectively. The incidence rate symptomatic FN at 6- 12-18-24 months were0.7%, 2.7%, 3.4% and 4.6% respectively. On univariate analyses, PTV (Continuous) and ≥ 80cc vs <80cc of PTV were predictive of FN with a p-value of 0.04 and <0.01 respectively; V19.3 (cc) (Continuous) and ≥ 5ccvs <5cc of V19.3 were predictive of FN with a p-value of <0.01 and <0.01 respectively and were predictive of symptomatic FN. Whole breast volume, clinical target volume (CTV), DMax PTV (Gy) were not significantly associated with FN on univariate analysis (Table 1). On multivariate analyses V19.3 ≥ 5cc remained a predictive factor for FN (p-value 0.02; OR 3.79; CI95 1.21-11.8). V19.3 % (Continuous) remained a predictive factor for symptomatic FN (p-value 0.01; OR 1.09; CI95 1.01-1.17).
Long-Term Survival after Brain Metastases in Breast Cancer: The Central Role of Intracranial Disease Control Luisa Allwohn 1 , Alexander Soppa 1 , Sophia Kiesl 1 , Sophie T. Behzadi 1 , Sophie Maier 1 , Rebecca Moser 1 , Jana Nano 1 , Anne K. Krämer 2 , Denise Bernhardt 1 , Stephanie E. Combs 1,3 , Kai J. Borm 1 1 Radiation Oncology, TUM University Hospital, Munich, Germany. 2 Gynecology, TUM University Hospital, Munich, Germany. 3 German Cancer Consortium (DKTK), Partner Site Munich, Munich, Germany Purpose/Objective: Despite advances in systemic and local therapies, the median overall survival (OS) of patients with breast cancer brain metastases (BCBM) remains limited to 10–15 months [1,2]. However, a subset of patients achieves long-term survival after initial radiotherapy (RT). This study explores intracranial versus visceral disease control as a potential surrogate for RT efficacy and evaluates associated treatment-related toxicities. Material/Methods: This retrospective study included long-term survivors with BCBM who underwent initial RT for brain metastases at the TUM University Hospital between 2007 and 2022. Long-term survivorship was defined as an OS exceeding three times the median OS of all BCBM patients treated at our department, which was 12.3 months (range 0.2–109.7 months). Clinical and treatment-related data—including baseline characteristics, molecular subtype, RT parameters, and neurocognitive outcomes—were analyzed. Descriptive statistics were applied; OS was estimated using the Kaplan–Meier method. Results: A total of 35 patients met the inclusion criteria, with a median OS of 59.3 months (range 36.2–109.7 months). The median age at brain metastasis diagnosis was 54.5 years, and the median interval between primary breast cancer diagnosis and brain metastasis onset was 72.9 months. Median progression-free survival (PFS) following brain irradiation was 35.1 months. Twenty-four patients (68.6%) received initial stereotactic radiotherapy (SRT), while 11 (31.4%) underwent whole-brain radiotherapy (WBRT). During the intracranial progression-free interval, 22.9% of patients experienced visceral progression after a median of 23.4 months, whereas 77.1% maintained visceral disease control beyond intracranial progression. Among WBRT-treated patients, 27.2% developed visceral progression after a median of 28.6 months; among SRT-treated patients, 20.8% did so after a median of 20.3 months.Overall, 40% of patients developed grade ≥ 3 neurotoxicity during follow-up, with radionecrosis being the most frequent ≥ 3 toxicity
Conclusion: Early-stage breast cancer patients treated with single fraction stereotactic partial breast irradiation (S-PBI) had a low rate of FN. Based on this sub-analysis of a
phase II study, to reduce the risk of FN, we recommend not exceeding 105% of 5 cc. References:
Facondo G, Reverberi C, Prisco A, et al. Post-Operative Single Fraction Stereotactic Partial Breast Irradiation (S-PBI) for Early-Stage Breast Cancer with Gammapod™ Technology: A Phase II Clinical Trial. Int J Radiat Oncol Biol Phys. 2025 Oct 27:S0360- 3016(25)06400-4. doi: 10.1016/j.ijrobp.2025.10.018. Epub ahead of print. PMID: 41161644 Keywords: fat necrosis, PBI, single fraction stereotactic
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