ESTRO 2025 - Abstract Book

S154

Invited Speaker

ESTRO 2025

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Speaker Abstracts Hypoxia imaging using quantitative MRI in clinical trials Tord Hompland Radiation Biology, Oslo University Hospital, Oslo, Norway

Abstract: Tumor hypoxia, areas of low oxygen, is a major cause of radioresistance and treatment failure in modern radiation therapy. It is present in virtually all solid tumors, however, the level of hypoxia varies greatly between patients. Recently, it has been shown that in patients with less hypoxic tumors, defined by FMISO pet imaging, radiation dose can be lowered by 60% without reduction in therapeutic outcome (1). The reduction in dose was accompanied by a reduction in acute and late adverse events. This study highlights the importance and potential of including information on tumor hypoxia in a more personalized radiotherapy regimen. However, including hypoxia-based PET tracers into clinical practice is today unfeasible due to complicated logistics and huge costs. Furthermore, development of hypoxia targeted treatments to improve outcome in patients with hypoxic tumors, is dependent on hypoxia biomarkers for selecting those patients. Quantitative MRI (q-MRI) biomarkers of tumor hypoxia could provide a clinically feasible alternative to hypoxia PET tracers. A major challenge, however, is that MRI cannot provide direct information on oxygen content in tissue. Recent efforts have therefor focused on providing information on tumor hypoxia by imaging properties of the tissue that causes hypoxia. Hypoxia is a result of an imbalance between oxygen supply and demand and imaging parameters related to the function of tumor vasculature and number of oxygen consuming tumor cells has shown promise as hypoxia biomarkers (2). Our group has recently developed a hypoxia imaging tool based on this strategy, termed Consumption and Supply Based hypoxia imaging (3, 4). This tool combines images related to oxygen consumption and oxygen supply into images of hypoxia. We have biological validated this tool in experimental tumor models and in cervical, prostate and breast cancer patients. These studies are all single center studies, and the possibility of applying this tool in a multicentre setting is under investigation. q-MRI based tools to assess hypoxia are currently being tested in interventional trials aimed at targeting hypoxia. By providing patient selection and treatment monitoring, imaging hold the promise of speeding up and increasing the success rates of hypoxia targeting drug trials. I will present our experiences of setting up and performing a clinical trial to monitor the effect of Metformin on tumor hypoxia in cervical cancer patients using q-MRI (5). Furthermore, I will discuss the future challenges and future possibilities of applying MRI based measurements of tumor hypoxia in clinical trials.

References

1. Lee NY, J. Clin. Oncol. 2025 2. Hompland T, Cancers 2021 3. Hompland T, Cancer Res. 2018 4. Hillestad T, Cancer Res. 2020 5. Skipar K, Acta Oncol. 2025

4930

Speaker Abstracts The science of performance: Driving quality improvement in radiation oncology Isabel Syndikus, Rhiju Chatterjee Radiotherapy, Clatterbridge Cancer Centre, Liverpool, United Kingdom