ESTRO 2023 - Abstract Book

S632

Monday 15 May 2023

ESTRO 2023

Conclusion Preoperative single-dose PBI and BCS is a safe treatment with acceptable oncological outcomes, mild late toxicity, and satisfactory cosmetic results and quality of life at 5 years of follow-up. In the ongoing ABLATIVE-2 trial (NCT05350722), BCS is performed at a longer interval of 12 months after preoperative PBI. OC-0766 Gain from respiratory gating in left-sided partial breast irradiation in the DBCG PBI trial K. Høgsbjerg 1 , E. Maae 2 , A.N. Pedersen 3 , M. Møller 4 , M.H. Nielsen 5 , M.S. Thomsen 6 , B.V. Offersen 7 1 Aarhus University Hospital, Department of Oncology and Department of Experimental Clinical Oncology, Aarhus, Denmark; 2 Vejle Hospital, University Hospital of Southern Denmark, Department of Oncology, Vejle, Denmark; 3 Copenhagen University Hospital, Rigshospitalet, Department of Oncology, Copenhagen, Denmark; 4 Aalborg University Hospital, Department of Oncology, Aalborg, Denmark; 5 Odense University Hospital, Department of Oncology, Odense, Denmark; 6 Aarhus University Hospital, Department of Medical Physics, Aarhus, Denmark; 7 Aarhus University Hospital, Department of Experimental Clinical Oncology and Department of Oncology, Aarhus, Denmark Purpose or Objective Partial breast irradiation (PBI) has been Danish Breast Cancer Group (DBCG) standard treatment for selected breast cancer (BC) patients since 2016 based on early results from the randomised DBCG PBI trial. It is also DBCG standard to use respiratory gated radiation therapy (RGRT) in left-sided BC patients. RGRT was introduced in Danish centres during the accrual of patients in the trial. The purpose of our study is to investigate the effect of RGRT on mean heart dose (MHD) in left-sided PBI. Materials and Methods In total, 865 patients (434 WBI, 431 PBI) were randomised in in five centres in the DBCG PBI trial from 2009-2016, and 230 patients (27%) had left-sided PBI. These patients were separated into those with upper (tumor bed plus 3 mm from papilla and cranial) versus lower located tumors (the rest). MHD and use of RGRT was registered for all patients. The MHD was not normal distributed, and the p-value was therefore calculated by Wilcoxon-Mann-Whitney-test.