S300
Clinical - Breast
ESTRO 2026
optional boost/SIB of 0-16 Gy (median EQD2 60 Gy). Right-sided RT consisted of whole breast irradiation (WBI) in 82.5%, chest wall RT in 15.8%, and partial breast RT in 0.8%; 82.1% received no regional nodal irradiation (RNI). Left-sided RT followed a similar pattern (WBI 78.5%, chest wall 16.5%, partial breast 2.5%; 78.6% without RNI). Most patients were treated with 3D-CRT (65-75%), followed by IMRT/DMLC (20%) and VMAT (14-15%). With a median follow-up of 47.6 months (95% CI 30.4-57.8), locoregional failure-free survival was 95.9% at 3 years and at 5 years. Distant metastasis-free survival was 93.6% and 90% at 3 and 5 years, respectively. Acute toxicity mainly consisted of grade 1-2 dermatitis or fatigue, while grade ≥ 3 events were rare (<4%), and pneumonitis occurred in 2.7% of patients (Figure 1). Chronic toxicity was dominated by Grade 1-2 skin effects, with no higher-grade events (Figure 2). 38 patients completed QoL assessments (EORTC QLQ-C30 median score 6, IQR 4-6); 43% were very satisfiedwith breast appearance (BREAST-Q).
Lo AW, Ip MK, Chan LK, Cheng HC, Lee SF, et al. Pilot evaluation of Mepitel Film and StrataXRT for the prophylaxis of radiation dermatitis in Chinese breast cancer patients undergoing adjuvant radiotherapy in Hong Kong. Asia Pac J Oncol Nurs. 2025;12:100769. Keywords: radiation dermatitis, silicone gels Digital Poster Highlight 3346 Simultaneous bilateral breast irradiation (SBBI) in synchronous bilateral breast cancer (SBBC): experience from two German university hospitals Polina Yaremenko 1 , Jana Nano 1 , Montserrat Pazos 2 , Luisa Allwohn 1 , Sophie T. Behzadi 1 , Lena M. Buchecker 1 , Sophia Kiesl 1 , Sophie Maier 1 , Rebecca Moser 1 , Annemarie Zinn 2 , Stephanie E. Combs 1,3 , Claus Belka 2 , Stefanie Corradini 4 , Kai Borm 1 1 Department of Radiation Oncology, TUM School of Medicine and Health, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany. 2 Department of Radiation Oncology, LMU University Hospital, Munich, Germany. 3 Department of Radiation Sciences (DRS), Institute of Innovative Radiotherapy (iRT), Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Oberschleißheim, Germany. 4 Department of Radiation Oncology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen Nürnberg, Erlangen, Germany Purpose/Objective: Synchronous bilateral breast cancer (SBBC) accounts for 2-4% of breast cancer cases and poses technical challenges in radiotherapy, yet data on simultaneous bilateral irradiation (SBI) remain limited. This study reports clinical and patient-reported outcomes from two German university hospitals. Material/Methods: Patients with SBBC treated between 2010-2024 at the Technical University of Munich (n=46) and LMU Munich (n=65) were retrospectively identified. All patients received external beam radiotherapy to the breast and/or chest wall. Clinical, pathological, and dosimetric parameters were analyzed. Overall survival (OS), locoregional recurrence (LRR), and distant recurrence (DR) were estimated using the Kaplan- Meier method. Acute and late toxicities were graded according to CTCAE v5.0. A prospective study assessed patient-reported outcomes using EORTC QLQ-C30 and BREAST-Q questionnaires. Results: A total of 111 patients with SBBC were analyzed (median age 65 years, range 40-87). Most tumours were early stage (right breast: pT1b pN0; left breast: pT1c pN0); 23% of patients were treated using deep inspiration breath hold during radiotherapy. The median RT dose was 50.05 Gy in 25 fractions, with an
Figure 1: Acute toxicity grades for both breasts after SBI.
Figure 2: Chronic toxicity grades for both breasts after SBI. Conclusion: To our knowledge, this is the largest evaluation of SBI in SBBC, providing data on feasibility, toxicity, and PROMs. Our findings indicate excellent overall survival rates, confirming SBI as a feasible, safe, and effective treatment option. These results offer guidance for managing such scenarios. Keywords: Synchronous bilateral breast cancer irradiation
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