ESTRO 2025 - Abstract Book

S426

Clinical - Breast

ESTRO 2025

Conclusion: This study highlights the significant impact of socioeconomic disparities, pre-existing OA, and the timing of OA symptoms on AHT adherence and survival outcomes in breast cancer patients. Tailored interventions addressing these factors, particularly in vulnerable populations, are crucial for optimizing the long-term effectiveness of AHT and improving survival rates in breast cancer patients.

Keywords: Adherence, Disparities, Adjuvant Hormone Therapy

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Digital Poster Ultra-hypofractionated radiotherapy for breast cancer: Can we make it even faster? Raouia Ben Amor 1,2 , Bouchra Naija 1 , Ghada Bouguerra 1 , Zeineb Naimi 1,2 , Siwar Abdessaied 1,2 , Rihab Haddad 1 , Awatef Hamdoun 1,2 , Lotfi Kochbati 1,2 1 Radiation Oncology, Abderrahmen Mami Hospital, Ariana, Tunisia. 2 Faculty of Medecine of Tunis, Tunis El Manar University, Tunis, Tunisia Purpose/Objective: This study aimed to evaluate the dosimetric benefits of simultaneous integrated boost (SIB) compared to sequential boost (SEQB), which extends treatment time by one to two weeks, in ultra-hypofractionated radiotherapy (UHF-RT) for breast cancer. Material/Methods: We compared the dosimetric plans of 60 patients treated with UHF-RT. A delineation of the whole breast (WB), tumour bed (TB), heart and lungs was carried out. For each patient, 2 treatment plans were created depending on the boost technique: In the case of SEQB, the prescribed dose was 26 Gy for the WB (5 fractions of 5.2 Gy) followed by a boost of 10 Gy in 5 fractions. In the case of SIB, the prescribed dose was 26 Gy in 5 fractions for the WB with SIB of 4 Gy in the TB (total dose of 30 Gy in 5 fr of 6 Gy to the TB). Ballistics and dosimetry were carried out on the TPS Monaco, using a 3D conformal radiotherapy technique for the 2 boost techniques. The following dosimetric criteria were analysed by paired T-test: volumes receiving 95% (V95%) and 107% (V107%) of the prescribed dose for the target volumes, volume receiving 7 Gy and 1.5 Gy for the heart (V7 and V1.5), volume receiving 8 Gy (V8) for the lungs, heterogeneity index (HI) and conformity index (CI) for the target volumes.

Results: The mean V95% for WB and tumour bed was 97.51% versus 97.53%(p=0.3) and 98.9% versus 99.1%(p=0.18) in the