ESTRO 2025 - Abstract Book

S474

Clinical - Breast

ESTRO 2025

Conclusion: One-week UHF-WBI regimen is a feasible and well-tolerated treatment option for women with DCIS either after conservative surgery with or without the inclusion of a tumor bed SIB, or mastectomy. Further studies are recommended to confirm these preliminary findings and strengthen the evidence base.

Keywords: DCIS, ultra-hypofractionation

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Mini-Oral Intraoperative radiotherapy in elderly patients with breast cancer: long-term follow-up results of the prospective phase II trial TARGIT-E Elena Sperk 1,2 , Claire Lemanski 3 , Juliane Zahn 2 , Christian Neumaier 4 , Victor Siefert 2 , Ragna Völker 5 , Christoph Lindner 6 , Peter Niehoff 7 , Agnes Richard Tallet 8 , Séverine Racadot 9 , Adeline Petit 10 , Montserrat Pazos 11 , Magali Le Blanc Onfroy 12 , Etienne Martin 13 , Robert Michael Hermann 14 , Fabian Pohl 15 , Kay Friedrichs 16 , Steffi Pigorsch 17 , Hans Christian Kolberg 18 , Heiko Graf 19 , Thomas B. Brunner 20 , Wolfram Malter 21 , Marc Sütterlin 22 , Henrik Flyger 23 , Frederik Wenz 24 1 Mannheim Cancer Center, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany. 2 Department of Radiation Oncology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany. 3 Radiotherapy Department, ICM, Montpellier, France. 4 MVZ Strahlentherapie, Klinikum Worms, Worms, Germany. 5 Brustzentrum City, Sankt-Gertrauden-Krankenhaus, Berlin, Germany. 6 Frauenklinik, Agaplesion Diakonieklinikum, Hamburg, Germany. 7 Kliniken der Stadt Köln, Sana Klinikum Offenbach, University Witten Herdecke, Offenbach, Germany. 8 Radiotherapy Department, Insitut Paoli Calmettes, Marseille, France. 9 Radiotherapy Department, Centre Léon Bérard, Lyon, France. 10 Department of Radiation Oncology, Institut Bergonié, Comprehensive Cancer Center, Bordeaux, France. 11 Klinik und Poliklinik für Strahlentherapie und Radioonkologie, LMU Klinikum, Campus Innenstadt, Munich, Germany. 12 Insitute Cancerology, Ouest Nantes, Saint Herblain, France. 13 Radiotherapy Department, Centre Georges-François Leclerc, Dijon, France. 14 Center for Radiotherapy and Radiooncology Westerstede, Ammerlandklinik, Westerstede, Germany. 15 Department for Radiotherapy, Regensburg University Hospital, Regensburg, Germany. 16 Mammazentrum HH, Krankenhaus Jerusalem, Hamburg, Germany. 17 Department of RadioOncology, Technical University Munich, Munich, Germany. 18 Department for Gynecology and Obstetrics, Marienhospital Bottrop, Bottrop, Germany. 19 Südthüringer Brustzentrum, Helios Klinikum Meiningen, Meiningen, Germany. 20 Department of Radiation Oncology, University Medical Center Magdeburg, Magdeburg, Germany. 21 Breast Center, Faculty of Medicine and University Hospital, University of Cologne, Cologne, Germany. 22 Department for Gynecology and Obstetrics, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany. 23 Department of Breast Surgery, Herlev and Gentofte Hospital University of Copenhagen, Herlev, Denmark. 24 Chief executive Officer, University Hospital Freiburg, Freiburg, Germany Purpose/Objective: In clinical practice, radiotherapy (RT) after breast-conserving surgery (BCS) is often omitted for elderly patients with breast cancer (BC) due to fear of toxicity and/or comorbidities. Several studies have investigated the omission of RT after BCS in elderly patients and showed increased rates of local recurrence. With intraoperative radiotherapy (IORT), RT is targeted to the cancer site, performed directly during BCS and therefore time-saving. TARGIT-E is a prospective, multicentric single-arm phase II trial (NCT01299987) that investigates the efficacy and safety of a risk adapted approach consisting of a single dose of IORT followed by whole-breast radiation therapy (WBRT) only when risk factors were present in elderly patients. We here report long-term follow-up results of TARGIT-E (median follow up 5.4 years) on oncological outcome, late toxicities and cosmetic outcomes. Material/Methods: Elderly Patients with low-risk BC (≥70 years, cT1, cN0, cM0, invasive carcinoma of no special type) were enrolled at 27 centers in Europe. During BCS, a single dose of 20 Gy of low-energy IORT was given (Intrabeam, Carl Zeiss