ESTRO 2025 - Abstract Book

S472

Clinical - Breast

ESTRO 2025

Conclusion: The wiki Moja study demonstrates that a one-week hypofractionated radiotherapy regimen for breast cancer is a safe, effective, and efficient alternative to the traditional three-week regimen. While it offers significant advantages in patient convenience and cost, longer follow-up is essential to fully determine its impact on loco-regional cancer control post-surgery. This regimen has potential for integration into routine clinical practice, optimizing treatment for resource-constrained settings.

Keywords: Hypofractionation Breast Cancer Radiotherapy

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Digital Poster One-Hundred-and-One DCIS: Hunting down safe and effective results with 5-day ultra-hypofractionated irradiation Angel Montero 1,2 , Raquel Ciervide 1 , Ivica Ratosa 3 , Beatriz Alvarez 1 , Mariola Garcia-Aranda 1 , Jeannette Valero 1 , Mercedes Lopez 1 , Ovidio Hernando 1 , Emilio Sanchez 1 , Xin Chen-Zhao 1 , Miguel Sanchez 1 , Carmen Saiz 1 , Ana Fernandez 4 , Rosa Alonso 1 , Daniel Zucca 4 , Bruno Zambrana 1 , Pedro Fernandez-Leton 4 , Carmen Rubio 1,2 1 Radiation Oncology, HM Hospitales, Madrid, Spain. 2 Faculty of Health Sciences, Universidad Camilo José Cela, Madrid, Spain. 3 Radiation Oncology, Institute of Oncology Ljubljana, Lujbljana, Slovenia. 4 Medical Physics, HM Hospitales, Madrid, Spain Background: Ductal carcinoma in situ (DCIS) accounts for approximately 25-30% of new breast cancer diagnoses; however, it remains underrepresented in studies exploring the feasibility and safety of one-week ultrahypofractionated (UHF) radiation treatment. Materials and Methods: From January 2020 to December 2023, 101 women with a median age of 54 years (range 40-88) diagnosed with DCIS received UHF chest wall/whole breast irradiation to a total dose of 26 Gy in five fractions of 5.2 Gy. In all cases following breast-conserving surgery (90%), a simultaneous integrated boost (SIB) to the tumor bed was delivered, totaling 29-31 Gy over five fractions. Additionally, 79% of patients received adjuvant hormonal therapy. Patient characteristics are detailed in Table 1.