ESTRO 2025 - Abstract Book

S165

Brachytherapy -Breast

ESTRO 2025

835

Proffered Paper Local treatment of ipsilateral breast recurrences: 10-year results of a comparative analysis of alternative therapeutic options Viktor Smanykó 1,2,3 , Norbert Mészáros 1,3,2 , Georgina Fröhlich 1 , Tibor Major 1,3,2 , Csaba Polgár 1,3,2 1 Center of Radiotherapy, National Institute of Oncology, Budapest, Hungary. 2 National Tumor Biology Laboratory, National Institute of Oncology, Budapest, Hungary. 3 Department of Oncology, Semmelweis University, Budapest, Hungary Purpose/Objective: To report clinical outcomes, late side effects, and cosmetic results of second breast conserving therapy (2 nd BCT) with perioperative high-dose-rate multicatheter interstitial brachytherapy (HDR MIBT) versus salvage mastectomy (sMT) for the treatment of ipsilateral breast tumour recurrence (IBTR). Material/Methods: Between 1999 and 2015, 195 patients who presented with an IBTR after previous breast-conserving treatment were salvaged either with re-excision and perioperative HDR MIBT (n=39) or sMT (n=156). In the 2 nd BCT group a total dose of 22 Gy in 5 fractions of 4.4 Gy was delivered with catheters intraoperatively implanted in the tumour bed for 3 consecutive days. Results: The median follow-up time was 124 (range: 11-269) months in the 2 nd BCT and 110 (range: 5-285) months in the sMT group. The mean size of IBTR was 16 (range: 2-70) mm vs. 24 (range: 2-90) mm, respectively (p=0.0005), but there was no any other significant difference in pathological related parameters (histologic type and grade, margin status, receptor status) or in patient related parameters (age, menopausal status, mean time to recurrence) between the two groups. During the follow-up period, 7 out of 39 (17.9%) and 33 out of 156 (21.2%) 2 nd IBTR occurred in the 2 nd BCT and the sMT group, respectively. The 10-year actuarial rate of 2 nd IBTR was 18% vs. 20% (p=0.298), respectively. Similarly, no significant difference was found in the 10-year probability of regional recurrence-free survival, distant metastasis free survival, disease-free survival and cancer-specific survival, which were 95% vs. 89% (p=0.365), 78% vs. 62% (p=0.926), 78% vs. 58% (p=0.065) and 78% vs. 64% (p=0.071), in the same order. But significant differences were observed in the 10-year overall survival, which was 70% vs. 47% (p=0.027), respectively. The latter result can be explained by the significantly larger tumour size in the sMT group. After the 2 nd BCT, 72% of the patients had excellent or good cosmetic results based on the Harvard criteria. Grade 3 late skin toxicity occurred in 1 patient, and grade 3 fibrosis was detected in 2 women. Fat necrosis developed only in an asymptomatic form. Conclusion: This study is the first, which directly comparing the 10-years outcomes of 2 nd BCT to sMT in patients who were treated at the same institute and during the same period. Based on our findings, 2 nd BCT with perioperative HDR MIBT is a safe and feasible option for the management of IBTR, resulting in equivalent 10-year oncological outcomes and better cosmetic results compared to sMT.

Keywords: ipsilateral breast recurrence

2485

Poster Discussion Accelerated Partial Breast Irradiation (APBI) with multicatheter brachytherapy (BT) after second conservative surgery: a retrospective analysis.