ESTRO 2025 - Abstract Book

S547

Clinical - Breast

ESTRO 2025

Conclusion: Ex HFRT might be a better option in LABC. Further evidence from the results of ongoing prospective phase III trials like EXHYPO-LABC (CTRI/2023/04/051955) and HYPORT-Adjuvant (CTRI/2018/12/016816) are awaited to establish it in the LABC.

Keywords: Extreme hypofractionation, LABC

References: 1. Giridhar, P., Pradhan, S., Pujari, L., Singh, P., Shinghal, A., Khandelwal, C., Mukherjee, C., Tripathi, M., Shukla, V., M V, M., Choudary, Z., & Gupta, A. (2024). Is FAST FORWARD the Way Forward in Radiotherapy for Locally Advanced Breast Cancer - Learnings From the COVID Pandemic. Clinical breast cancer , 24 (3), e116–e125. 2. Chatterjee, S., Chakraborty, S., & HYPORT Adjuvant Author Group (2020). Hypofractionated radiation therapy comparing a standard radiotherapy schedule (over 3 weeks) with a novel 1-week schedule in adjuvant breast cancer: an open-label randomized controlled study (HYPORT-Adjuvant)-study protocol for a multicentre, randomized phase III trial. Trials , 21 (1), 819.

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Digital Poster Long-term outcome of Intraoperative Electron Radiation Therapy (IOERT) as boost followed by whole breast irradiation in breast Cancer Christiane Matuschek 1 , Iris Hiller 1 , Bláthin Elsheimer 2 , Jan Haussmann 2 , Danny Jazmati 2 , Wilfried Budach 2 , Edwin Bölke 2 , Tanja Fehm 3 , Svjetlana Mohrmann 3 , Eugen Ruckhäberle 3 , Juliane Hörner-Rieber 2 1 Radiation Oncology, Bielefeld University, Medical School and University Medical Center OWL, Bielefeld, Germany. 2 Radiation Oncology, Heinrich Heine University, Dusseldorf, Germany. 3 Gynecology, Heinrich Heine University, Dusseldorf, Germany Purpose/Objective: Intraoperative electron radiation therapy (IOERT) applied for boost followed by whole breast irradiation (WBI) is an established procedure in the treatment of primary operable breast cancer. However, long-term follow-up is still sparse. Material/Methods: 161 patients treated for primary operable breast cancer between December 2011 and November 2019 at the Department of Radiation Oncology at University Hospital Düsseldorf, Germany outside prospective trials were identified in our in-house database. During breast-conserving surgery (BCS), an IOERT boost with 1 x 10 Gy was administered followed by WBI with either 5 x 2.7 Gy to 40.5 Gy or 5 x 1.8 Gy to 50.4 Gy. All patients were prospectively invited for long-term follow-up examinations in May 2020 to October 2021, including cosmetic assessment by the Harvard scale and evaluation of late side effects according to LENT-SOMA criteria. Results: Forty-four patients (27.3%) underwent long-term follow-up examinations with a median follow-up time of 52 months (range: 18-108 months). Cosmetic outcomes were rated as “very good”, “good”, “moderate” and “poor” by 59.1% (n=26), 22.7% (n=10), 11.4% (n=5) and 6.8% (n=3), respectively. 27.3% of patients (n=12) reported mild pain in the former irradiation field with 25% (n=11) rating it as grade 1 and 2.3% (n=1) as grade 2, grade 1 and 2 edema occurred in 6.8% (n=3) and 2.3% (n=1) of cases, respectively. Grade 1 fibrosis was observed in 18.2% (n=8) of patients and grade 2 in 9.1% (n=4) Grade 1 Telangiectasia were detected in 6.8% of patients (n=3), while fat necrosis grade 1 was seen in 2.3% (n=1) and arm edema grade 1 in 11.4% of patients (n=5), respectively. Three- and five-year overall survival rates were 99% and 95% with recurrence occurring in 7.0 % (11/157) of patients. Locoregional recurrence was seen in 2.5 % (n=4) and distant metastases were diagnosed in 5.7% (n=9). Notably, only