S872
Clinical - Mixed sites & palliation
ESTRO 2026
retrospective study assessed the efficacy and safety of HA-HSRT as a post-operative adjuvant therapy. Material/Methods: From January 2023 and September 2025, 27 consecutive patients (age 18 years or older - KPS ≥ 70) with 28 surgical beds and with a resection cavity less 5 cm in maximal extense. Median GTV was 14.9 cc (3.3- 40.4). Median PTV 28.7cc (range 11.7-62.2) underwent HA-HSRT within 2.7-6.6 weeks (median 4.9) after surgery. Treatment dose were either 27Gy/3fractions or 30Gy/5 fractions (once daily, three fractions weekly) prescribed on 100% peripheral isodose. The fractionation schema was selected by the treating physician based on clinical judgment. The treatment plan ensured for PTV (Dmax<140%, D98%>100%) and GTV (Dmax<140%, D100%>100%). Seventeen patients received concomitant systemic therapy. Results: The median follow-up period was 9.5 months (range 2.3-19.7). One local relapse at 4.3 months was reported. The median LC was not reached; the 6- month LC rate was 94%. Five deaths were reported: two cases were due to an intracranial progression (one with extra-PTV progression and one with intra- & extra-PTV progression) and three cases were due to extracranial progression. The median OS was not reached; the 6-month local OS was 90 %. Symptomatic grade 2 acute neurologic toxicity was observed in 7 patients.One case of asymptomatic radiation necrosis (grade 1) occurred 14 months after HA-HSRT in a previously irradiated BM 2 years before.All OAR dose constraints were respected for healthy tissue, except for 2 patients for normal brain constraint in regimen 5*6Gy. Conclusion: This retrospective study of patients undergoing surgical resection for large BM indicates that HA-HSRT administered to the resection cavity should lower local recurrence with limited toxicity. These results confirm the growing interest in this technology, which deserves validation by larger series and longer follow-up. Keywords: BRAIN METASTASIS Safety and Efficacy of Spinal Re-Irradiation: Preliminary Results from the Multicentric RIMESPINE Trial Donato Pezzulla 1 , Liliana Belgioia 2,3 , Valentina Borzillo 4 , Savino Cilla 5 , Saide Di Biase 6 , Nadia Di Muzio 7,8 , Costanza Donati 9,10 , Chiara Lucrezia Deantoni 7 , Andrei Fodor 7 , Gabriella Macchia 1 , Simona Mercogliano 4 , Esmeralda Scipilliti 4 , Miriam Torrisi 11 , Giorgia Timon 2,3 , Maddalena Trozzi 12 , Giulia Vidano 3 , Francesco Digital Poster 1385
70 (IQR 57-76), and 53% were male. Lung, breast, prostate, and renal cancer accounted for 70% of primary diagnoses. Twenty-nine (12%) patients received 8 Gy/1Fx, 131 (54%) received 25 Gy/5Fx, and 83 (34%) received 30 Gy/10Fx. Fourteen patients underwent postoperative radiotherapy.Median overall survival for all patients was 5.1mo (95%CI 4.2;6)). Median overall survival was 3.4 (95%CI 2.4;4.4), 3.7 (95%CI 2.2;5.3) and 10 mo (95%CI 1.8;18.3) for patients treated with 8 Gy/1Fx, 25 Gy/5Fx, and 30 Gy/10Fx respectively. There was no difference in survival in patients treated with 8Gy/1Fx and 25Gy/5Fx (p =0.97). Of the 28 (12%) patients that died within one month after treatment start – only seven received single
fraction RT. Conclusion:
The lack of difference in overall survival between patients treated with 8Gy/1Fx and 25Gy/5Fx suggests that clinicians may overestimate survival, leading to overtreatment. These findings highlight the need for prognostic tools to better tailor palliative radiotherapy in MSCC patients. References: A M Nielsen et al.: Interim analysis of patient-reported outcome compliance and dosimetry in a phase 3 randomized clinical trial of oesophagus-sparing spinal radiotherapy. Acta Oncol. 2023 Nov;62(11):1496-1501 Keywords: Metastatic Spinal Cord Compression Preliminary Experience of HyperArc Stereotactic Radiotherapy for Resected Large Brain Metastases Hajar Benabdesselam 1 , Inas Afkir 1 , Emmanuel Mesny 1 , Lucie Brun 1 , Chloe Dumot 2 , Clementine Gallet 2 , Fatima Ameur 3 , Vlad Galatan 1 , Anne D'Hombres 1 , Loic Feuvret 1 1 RADIATION THERAPY, HOSPICES CIVILS DE LYON, BRON, France. 2 NEUROSURGERY, HOSPICES CIVILS DE LYON, BRON, France. 3 NEURORADIOLOGY, HOSPICES CIVILS DE LYON, PIERRE BENITE, France Digital Poster 1375 Purpose/Objective: IntroductionSurgery alone for large brain metastases (BM) often results in local recurrence due to microscopic residual tumor tissue. While stereotactic radiosurgery is commonly used post-surgery, hypo- fractionated stereotactic radiotherapy (HSRT) appears as a valid treatment after large BM resection. Hyper Arc (HA-HSRT), (Varian Medical Systems, Palo Alto, CA) is an advanced platform that automates single- isocenter, non-coplanar VMAT planning and delivery, enabling highly conformal dose distributions with rapid dose fall-off outside the target.ObjectiveThis
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