S3033
Invited Speaker
ESTRO 2026
designs. By reconsidering how we design, conduct, and evaluate clinical research, radiation oncology can move beyond a one-size-fits-all reliance on traditional
based research include inconsistent validation, unclear sampling strategies, and limited transparency in analysis. This framework supports improved methodological rigour and consistency in reporting. Survey-based research is an increasingly important methodology within radiation oncology. This session will provide attendees with a practical, step-by-step approach to conduct their own high-quality survey research, supporting stronger study design, improved reporting, and greater impact within the radiotherapy
RCTs and toward a more adaptable and patient-centered evidence ecosystem.
5420 From biology to benefit: Why combine radiotherapy with targeted radionuclide therapy? Katherine A Vallis Oncology, Oxford University, Oxford, United Kingdom The case for combining external beam radiotherapy (EBRT) with regional or systemic delivery of an anticancer radiopharmaceutical is a compelling one. Carefully designed treatment protocols that take account of the differences in the radiobiological effects of the two modalities are needed to rationally explore this relatively new therapeutic approach. The combination of EBRT and radiopharmaceutical therapy (RPT) carries the potential gain of in-field co- operation. As an example, there is pre-clinical evidence that delivery of EBRT to a tumour enhances accumulation of a subsequently administered RPT, possibly through increased perfusion. In contrast, prior low dose rate irradiation by an RPT may cause a radioadaptive response and resistance to treatment with high dose rate EBRT. There is a growing body of evidence that EBRT can induce the expression of PSMA and SSTR2 on prostate cancer and neuroendocrine tumour cells respectively. If validated this phenomenon could be exploited to enhance binding and retention of subsequently delivered PSMA and SSTR2-targeting RPTs. The precise timing to take maximum advantage of this interaction requires careful investigation. Combining RPT and EBRT may also act synergistically to enhance antitumor immunity by promoting immunogenic cell death and increasing T-cell infiltration. However, it is also becoming clear that the effects of the EBRT and RPT on the tumour immune landscape differ, and that it may be possible to offset the immunosuppressive effects of one by the other. The synchronous delivery of radiation to multiple metastases appears to induce a strong abscopal effect, another opportunity to capitalise on combinations of EBRT and RPT. Radiobiological models, including the biological effective dose (BED) model, were originally developed for EBRT and they assume high dose rates and uniform dose delivery. In contrast, RPT delivers radiation continuously at low dose rates and is often heterogeneously distributed due to variable receptor density and perfusion. In particular, the role of DNA repair kinetics in shaping RPT outcomes remains unclear. This raises questions about the applicability of EBRT-derived radiobiological models to RPT.
community. References: 1.
Webster, A., et al., ESTRO guidelines for developing questionnaires in survey-based radiation oncology research. Clinical and Translational Radiation Oncology, 2025. 51: p. 100895.
5418 Beyond RCT: Innovative ways to generate high level evidence Erin F Gillespie Radiation Oncology, University of Washington, Seattle, USA Randomized controlled trials (RCTs) have long been considered the gold standard for generating evidence in radiation oncology. While essential for establishing efficacy and safety, traditional RCTs can be slow, costly, and limited in their ability to reflect real-world practice. As cancer care evolves rapidly, there is an increasing need for study designs that generate timely, generalizable, and implementation-relevant evidence. This talk will explore innovative approaches to evidence generation that extend beyond conventional trials, while recognizing the need to balance pragmatism and scientific rigor. We will review the four phases of clinical trials and introduce hybrid effectiveness–implementation trial designs as an opportunity to accelerate evidence generation by simultaneously evaluating clinical outcomes and strategies for integrating evidence-based interventions into routine practice. We will discuss pragmatic clinical trials, which aim to answer questions relevant to real-world decision-making by using broad eligibility criteria, flexible interventions, and outcomes meaningful to patients and health systems. We will address benefits and limitations to cluster trial designs, and present emerging opportunities for innovation such as two-stage and alternative consent models which are designed to reduce participation burden, improve inclusivity, and better align with patient preferences. Finally, we will encourage clinical trial recruitment itself as an object of study rather than a fixed process, helping to address persistent challenges of slow accrual and representativeness that limit timeliness and impact of more traditional trial
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