ESTRO 2025 - Abstract Book

S172

Brachytherapy -Breast

ESTRO 2025

4003

Digital Poster Long-term outcomes of interstitial multi-catheter HDR partial breast brachytherapy: results from a phase II study with an extended follow-up Valeria Epifani 1 , Giulia Mascari 1 , Fabio Arcidiacono 2 , Paola Anselmo 2 , Isabella Palumbo 1,3 , Gianluca Ingrosso 1,3 , Vittorio Bini 4 , Fabio Trippa 2 , Cynthia Aristei 1,3 1 Radiation Oncology Section, University of Perugia, Perugia, Italy. 2 Radiotherapy, Saint Maria Hospital, Terni, Italy. 3 Radiation Oncology Section, Perugia General Hospital, Perugia, Italy. 4 Internal Medicin, endocrine and metabolic section, University of Perugia, Perugia, Italy Purpose/Objective: To evaluate the long-term outcomes in patients treated with accelerated partial breast irradiation (APBI) using interstitial multi-catheter high-dose-rate (HDR) brachytherapy. Material/Methods: A total of 292 patients, with median age of 67 years (range 42-88) underwent APBI via HDR brachytherapy (4 Gy twice daily, total dose of 32 Gy) and were monitored for up to 20 years. The most frequent histology was infiltrating carcinoma (92.1%). Follow-up assessments included evaluation of local recurrence and cosmetic outcomes. Results: Median follow-up was 102 months (range 3-243). Ipsilateral breast tumor recurrence occurred in 8 patients (2,7%) at a median of 101 months post-APBI. Regional nodal recurrences were observed in 7 patients (2,4%) at a median of 102 months, while distant metastases developed in 14 patients (4,8%) at a median of 102 months. 17 patients (5,8%) developed a contralateral breast cancer and 52 patients (17,8%) had a second tumor. Breast cancer-specific survival was 98.9%, 95.7% and stable to 95.7%, respectively after 5, 10 and 15 years. Acute toxicity was documented in 97 patients (33,2%). Late toxicity was observed in 100 patients (34,2%). Some patients experienced more than one type of late toxicity. The most common late toxicities were telangiectasia (53 cases, 18.2%) and fibrosis (47 cases, 16.1%), followed by liponecrosis in 21 patients (7,2%). Cosmetic outcomes, as assessed by physicians, were rated as excellent in 206 patients (70,5%), good in 44 (15,1%), fair in 10 (3,4%), and poor in 1 (0,3%). Patient self assessments rated outcomes as excellent in 186 patients (63,7%), good in 44 (15,1%), fair in 10 (3,4%), and poor in 0. Physician and patient agreement on cosmetic outcomes was strong, with a weighted k-value of 0.73. Conclusion: APBI using interstitial multi-catheter HDR brachytherapy was associated with a low incidence of recurrence and toxicity, with favorable long-term outcomes at an extended follow-up period.

Keywords: Log-term results, recurrence, toxicities