S406
Clinical - Gynaecological
ESTRO 2026
metachronous, repeat, and induced lesions. Actuarial outcomes were estimated using the Kaplan–Meier method, with group differences assessed by log-rank tests and prognostic value evaluated via Cox regression. Results: Between May 2019 and January 2025, 262 patients (502 lesions) were treated with SBRT. Median follow-up was 48 months (range 3– 58). Induced lesions were most common (54.0%), followed by repeat (33.5%) and metachronous (12.5%). Two-year LC, DMFS, PFS, and OS were 77.7%, 20.4%, 19.1%, and 77.4%, respectively. Significant differences were found for DMFS (P=0.044) and a trend for PFS (P=0.053), with metachronous lesions showing the best outcomes, repeat intermediate, and induced the worst. Using the macro-classification, DMFS (P=0.004) and PFS (P=0.005) remained significant. Cox regression confirmed induced lesions as negative prognostic factors for LC (HR 2.282, 95% CI 1.040–5.008, P=0.04), DMFS (HR 1.83, 1.212–2.757, P=0.004), and PFS (HR 1.797, 1.201–2.690, P=0.004). Conclusion: This study first applied the ESTRO–EORTC oligometastatic disease classification to ovarian cancer, showing its ability to distinguish prognostic groups among patients treated with metastasis-directed SBRT—particularly for DMFS and PFS—and supporting early referral to radiation oncology to optimize outcomes without added toxicity. References: 1.Macchia G, Pezzulla D, Campitelli, et alTreatment of Oligometastatic Parenchymal Lesions in Ovarian Cancer With Stereotactic Ablative Radiation Therapy: A Multicenter Prospective Phase 2 Trial (MITO RT3/RAD). doi: 10.1016/j.ijrobp.2025.03.032. 2. Macchia G, Campitelli M, Pezzulla D, et al. Stereotactic Ablative Radiation Therapy for Oligometastatic Ovarian Cancer Lymph Node Disease: The MITO-RT3/RAD Phase II Trial. doi:
10.1016/j.ijrobp.2024.09.036. 3.Guckenberger M, Lievens Y, Bouma AB, et al. Characterisation and classification of oligometastatic disease: a European Society for Radiotherapy and Oncology and European Organisation for Research and Treatment of Cancer consensus recommendation. doi: 10.1016/S1470- 2045(19)30718-1. Keywords: Ovarian Cancer, SBRT, Oligometastases Toxicity profile of sbrt after Bevacizumab in oligometastatic ovarian cancer: a new perspective for radiation oncologists? Gabriella Macchia 1 , Pezzulla Donato 1 , Maura Campitelli 2 , Raffaella Cioffi 3 , Savino Cilla 4 , Simona Lucci 2 , Mara Fanelli 5 , Andrei Fodor 6 , Donatella Russo 7 , Vittoria Balcet 8 , Stefano Durante 9 , Francesca Titone 10 , Giuseppe Roberto D'Agostino 11 , Francesca De Felice 12 , Proffered Paper 691 Lorena Draghini 13 , Lucia Giaccherini 14 , Francesca Tortoreto 15 , Anna Fagotti 16 , Francesco Deodato 1,17 , Giorgia Mangili 3 1 Radiation Oncology Unit, Responbsible Research Hospital, Campobasso, Italy. 2 Dipartimento di Diagnostica per Immagini e Radioterapia Oncologica, Dipartimento di Scienze Radiologiche, Radioterapiche ed Ematologiche, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy. 3 Department of Obstetrics and Gynecology, IRCCS San Raffaele Scientific Institute, Milan, Italy. 4 Medical Physics Unit, Responbsible Research Hospital, Campobasso, Italy. 5 Research laboratories, Responbsible Research Hospital, Campobasso, Italy. 6 Department of Radiation Oncology, IRCCS San Raffaele Scientific Institute, Milan, Italy. 7 Radiotherapy Unit, “Vito Fazzi” Hospital, Lecce, Italy. 8 UOC Radioterapia, Nuovo Ospedale degli Infermi, Biella, Biella, Italy. 9 Division of Radiation Oncology, European Institute of Oncology, IEO, IRCCS, Milan, Italy. 10 Radiation Oncology
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