ESTRO 2025 - Abstract Book

S1538

Clinical – Mixed sites & palliation

ESTRO 2025

Conclusion: This study highlights the effectiveness of Linac-based VMAT for SRT/SBRT in managing brain, lung, and liver lesions, achieving superior local control and impacting overall survival. The integration of advanced imaging, precise dosimetric planning, and robust quality assurance makes SRT/SBRT as a reliable and impactful treatment modality in modern radiation oncology.

Keywords: SBRT, SRT, VMAT

References: 1. Pursley J, Wiant D, Terrell J, Sintay B. SU-E-T-641: Flattening Filter Free Dynamic Conformal Arcs for Lung Radiotherapy. Med Phys. 2012;39:3853. 2. Ballangrud Å, Kuo LC, Happersett L, Lim SB, Beal K, Yamada Y, Hunt M, Mechalakos J. Institutional experience with SRS VMAT planning for multiple cranial metastases. J Appl Clin Med Phys. 2018;19:176 – 183. doi: 10.1002/acm2.12284. 3. Méndez Romero A, Wunderink W, Hussain SM, De Pooter JA, Heijmen BJM, Nowak PCJM, et al. Stereotactic body radiation therapy for primary and metastatic liver tumors: a single institution phase i-ii study. Acta Oncol Stockh Swed. 2006;45(7):831 – 7.

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Digital Poster Trends in fractionation patterns for bone metastases: a retrospective multi-center study Ellis Slotman 1,2 , Heidi P Fransen 1 , Roxanne Gal 3 , Joanne M van der Velden 4 , Enja J Bantema-Joppe 5 , Inge Compter 6 , Judi NA van Diessen 7 , Mirjam Mast 8 , Janine GH van Nes 5 , Paulien G Westhoff 9 , Eva Versteijne 10,11 , Kim Wortel 12 , Eva de Wee 13 , Natasja JH Raijmakers 1 , Yvette M van der Linden 14,1 1 Research and development, Netherlands Comprehensive Cancer Organisation, Utrecht, Netherlands. 2 Health Technology and Services Research, University of Twente, Enschede, Netherlands. 3 Division of Imaging and Oncology, University Medical Center Utrecht, Utrecht, Netherlands. 4 Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, Netherlands. 5 Department of Radiation Oncology, Radiotherapy Institute Friesland, Leeuwarden, Netherlands. 6 Department of Radiation Oncology, Maastro, Maastricht, Netherlands. 7 Department of Radiotherapy, Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital, Amsterdam, Netherlands. 8 Department of Radiotherapy, Haaglanden Medical Center, Leidschendam, Netherlands. 9 Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, Netherlands. 10 Department of Radiation Oncology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, Netherlands. 11 Cancer Treatment and Quality of Life, Cancer Center Amsterdam, Amsterdam, Netherlands. 12 Department of Radiotherapy, Noordwest Ziekenhuisgroep Alkmaar, Alkmaar, Netherlands. 13 Department of Radation Oncology, Institute Verbeeten (BVI), Tilburg, Netherlands. 14 Department of Radiation Oncology and Centre of Expertise in Palliative Care, Leiden University Medical Center, Leiden, Netherlands Purpose/Objective: For uncomplicated bone metastases a single fraction of 8 Gy is considered the golden standard. In contrast, for more complicated bone metastases often multiple fractions are applied. The COVID-19 pandemic may have increased the adoption of hypofractionated schedules (1-2 fractions of 8 Gy) also for the latter to reduce hospital visits and optimize resources. This study aimed to evaluate trends in fractionation patterns and to report pain response in patients treated with hypofractionated regimens versus those receiving multiple fractions. Material/Methods: Data on treatment regimens for bone metastases between 2018 and 2022 were collected from 5 large radiotherapy institutions out of 21 in the Netherlands. Stereotactic radiotherapy regimens were excluded. Trends in the use of hypofractionated (1x8 Gy or 2x8 Gy) and multiple- fraction regimens (≥5 fractions) were analyzed descriptively over