ESTRO 2025 - Abstract Book

S523

Clinical - Breast

ESTRO 2025

Conclusion: Breast cancer patients who receive postoperative irradiation with the VMAT technique are exposed to a significant dose, even when the IMA is not included in the treatment field; however, this dose does not reach the therapeutic levels. Further studies are warranted to assess the necessity of IMN irradiation and its impact on clinical practice.

Keywords: breast cancer, internal mammary node, VMAT

References: Behzadi ST, Duesberg M, Moser R, et al. Incidental dose distribution to contralateral internal mammary nodes in breast cancer patients undergoing adjuvant radiotherapy. Clin Transl Radiat Oncol . 2024;48:100831. Published 2024 Jul 30. doi:10.1016/j.ctro.2024.100831 START Trialists' Group, Bentzen SM et al. The UK Standardisation of Breast Radiotherapy (START) Trial B of radiotherapy hypofractionation for treatment of early breast cancer: a randomised trial. Lancet . 2008;371(9618):1098-1107. doi:10.1016/S0140-6736(08)60348-7 Mini-Oral Ultra-hypofractionated WBI in early stage breast cancer: an Italian multicentric observational study (NCT05586256). Anna Giulia Becchetti 1 , Isabella Palumbo 1,2 , Maria Carmen De Santis 3 , Alessandra Fozza 4 , Luciana Rago 5 , Francesca De Felice 6,7 , Sara Falivene 8 , Marianna Nuzzo 9,10 , Paola Anselmo 11 , Valeria Masiello 12 , Anna Rita Musu 13 , Francesca Cucciarelli 14 , Damiana Andrulli 15 , Francesca Mascioni 16 , Gabriella Macchia 17 , Michele Antonello 18 , Agnese Prisco 19 , Francesca Corazzi 20 , Elisa D'Angelo 21 , Alba Fiorentino 22 , Antonella Fontana 23 , Elisabetta Bonzano 24,25 , Giuseppina Rossana Tola 26 , Vittorio Bini 27 , Cynthia Aristei 1,2 1 Radiation Oncology Section, University of Perugia, Perugia, Italy. 2 Radiation Oncology Section, Perugia General Hospital, Perugia, Italy. 3 Radiation Oncology Department, National Cancer Institute, Milano, Italy. 4 Radiation Oncology Section, IRCCS Ospedale Policlinico San Martino, Genova, Italy. 5 Radiology Department, IRCCS-CROB, Rionero in Vulture (Potenza), Italy. 6 Radiation Oncology, AOU Policlinico Umberto I, Roma, Italy. 7 Department of Radiological, Oncological and Pathological Sciences, "Sapienza" University of Rome, Roma, Italy. 8 Department of Radiotherapy, ASL Napoli1 Centro - Ospedale del Mare, Napoli, Italy. 9 Radiation Oncology Unit, SS. Annunziata Hospital, Chieti, Italy. 10 Radiation Oncology Unit, "G. D'Annunzio" University of Chieti, Chieti, Italy. 11 Radiotherapy Oncology Center, S. Maria Hospital, Terni, Italy. 12 Radiation Oncology Unit, Department of Radiology, Radiation Oncology and Hematology, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Roma, Italy. 13 Struttura Complessa di Radioterapia Oncologica, Ospedale San Francesco, Nuoro, Italy. 14 Radiotherapy Department, Azienda Ospedaliero Universitaria delle Marche, Ancona, Italy. 15 Radiotherapy Unit, Azienda Ospedaliera San Giovanni Addolorata, Roma, Italy. 16 U.O. Radioterapia Oncologica, AST Macerata, Macerata, Italy. 17 Radiation Oncology Unit, Responsible Research Hospital, Campobasso, Italy. 18 Dipartimento di Radiologia Clinica e Neuroscienze U.O.C. Radioterapia Oncologica, Azienda U.l.S.S Serenissima Ospedale dell’angelo Mestre, Mestre, Italy. 19 Department of Radiation Oncology, University Hospital of Udine, ASUFC, Udine, Italy. 20 Department of Radiation Oncology, Città di Castello Hospital, Città di Castello, Italy. 21 Radiation Oncology Department, Bellaria Hospital, AUSL, Bologna, Italy. 22 Dipartimento di Radioterapia Oncologica, Ente Ecclesiastico Ospedale Generale Regionale F. Miulli, Acquaviva delle Fonti(BA), Italy. 23 Radiotherapy Department, Santa Maria Goretti Hospital, Latina, Italy. 24 Radiation Oncology Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy. 25 Radiation Oncology Department, University of Pavia, Pavia, Italy. 26 Struttura complessa di Radioterapia, Azienda Ospedaliero universitaria di Sassari, Sassari, Italy. 27 Internal Medicine, Endocrinal and Metabolic Science, University of Perugia, Perugia, Italy Purpose/Objective: To confirm the results of the FAST-forward trial 1 a multicentric retrospective and prospective observational study was designed. 2369