S3039
Invited Speaker
ESTRO 2026
5437 Scaling safe reirradiation: Lessons learnt from streamlining reirradiation in a high-volume US centre Charles K Matrosic Department of Radiation Oncology, University of Michigan, Ann Arbor, USA Advancements in cancer care and detection, along with an aging population, have made reirradiation (reRT) relatively common in radiotherapy. Given the complexity of cumulative dose assessment and risk of toxicity, structured workflows are critical for safe and reproducible reRT practice. To address the growing number of reRT patients, a standardized reRT special medical physics consultation (SMPC) workflow was established in 2017 at the University of Michigan Department of Radiation Oncology to guide and document clinical decision- making. Since implementation, more than 3000 reRT- SMPCs have been performed at University of Michigan. This teaching lecture will present the implementation of a standardized reRT workflow in a high-volume radiation oncology department and summarize lessons learned over nine years. The workflow design, documentation strategies, and supporting technologies will be described, along with the clinical effort required and how these components have evolved over time. Trends in institutional reRT practice and their impact on clinical workflow will be presented using seven years of reRT SMPC data. Practical recommendations for implementing scalable and safe reRT workflows in other institutions will be highlighted. 5438 From concept to clinic: Lessons in designing and auditing radiotherapy protocols Lone Hoffmann Department of Oncology, Aarhus University Hospital, Aarhus, Denmark Reirradiation has emerged as a viable therapeutic option for selected patients, driven by advances in imaging, treatment planning, and delivery techniques. However, its implementation in routine clinical practice remains complex, requiring robust protocol design, coordinated data collection, and rigorous quality assurance (QA). This work outlines key lessons learned in translating reirradiation from concept to clinic, with a focus on designing and auditing radiotherapy protocols within multicentre settings. A crucial precursor to establishing clinical trials or registries is the creation of a structured forum supported by dedicated working groups focusing on
key domains such as clinical data, technical aspects, and legal considerations. These groups should meet regularly, both online and in person, to ensure alignment, foster collaboration, and iteratively refine protocols. This model has proven instrumental in Denmark, where initiatives such as the CURE Lung trial (NCT06950073) and the upcoming Prospective RegIstry for Oncologic Reirradiation (PRIOR) were built upon multidisciplinary working groups. These groups established and published standards for clinical workflow [1], image registration [2], dose planning [3], integration of clinical data from prior and current treatments, the definition of trial endpoints, and number of patients treated with reirradiation [4]. The development of large-scale clinical trials or registries requires clear organizational structures and active engagement of participating centres. Defined governance, transparent communication pathways, and shared responsibilities are essential for consistency and long-term sustainability. Equally important is the selection of meaningful endpoints, including toxicity, local control, survival outcomes, and patient-reported quality-of-life measures, supported by standardized data collection. Efficient data collection must balance completeness
with feasibility. The use of digital platforms, standardized case report forms, automated
radiotherapy data extraction, and integration into clinical workflows helps streamline processes and improve data quality while minimizing administrative burden. Quality assurance remains central throughout all phases. Pre-trial QA should include benchmarking exercises, and validation of contouring and planning approaches across centres. On-trial QA requires continuous monitoring of protocol adherence, timely case review, and mechanisms to address deviations. In busy clinical settings, a dedicated QA group can play a pivotal role in maintaining standards and ensuring consistency. Sustaining momentum is critical for success. Regular workshops, virtual meetings, and multidisciplinary case discussions promote engagement, facilitate knowledge sharing, and reinforce protocol adherence. In conclusion, successful implementation of reirradiation protocols depends on structured collaboration, efficient data strategies, and robust QA frameworks, enabling safe and effective integration into clinical practice. References: [1] Kaplan LP, et al. Clinical workflow for reirradiation: national consensus recommendations on imaging, treatment planning, dose accumulation, and treatment delivery. Acta Oncol. 2025;64:946-956. [2] Sand H, et al. Standardising image registration and dose mapping for thoracic reirradiation: A national
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