ESTRO 2024 - Abstract Book

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Invited Speaker

ESTRO 2024

Antje Dietrich

German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center (DKFZ), OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, TU Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany

Abstract:

The variable relative biological effectiveness (RBE) of protons has been evident in numerous preclinical in vitro studies. Few in vivo data are also available, but the clinical relevance remains unclear, as radiation plans in practice are robust against uncertainties of all kinds (range, positioning, motion, and also RBE). However, it is expected that this relevance will increase in certain target regions with increasing precision of clinical irradiation techniques. Suitable preclinical models are essential, as the exact mechanisms of (late) effects are often not fully understood. In my talk, I will provide an overview of in vivo data on RBE variations and discuss them in light of current knowledge about biological mechanisms of side effects. I will provide deeper insight data from our mouse model for precise proton irradiation induced brain damage. We utilize quantification of neuroinflammation at the individual cell level in whole-brain histology of mice showing late effects that reflect the clinical situation known from some patients after cranial (proton) irradiation. Our results suggest that inflammation mediated by microglia plays an important role in the pathogenesis of radiation-induced brain damage. The data also indicates that inflammatory processes are crucial for understanding the sensitivity of the periventricular region. Furthermore, I will use our data to showcase uncertainties of such in vivo experiments and draw lessons for future biological investigations of proton irradiation.

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Prognostic and longitudinal imaging biomarkers for dose-painting

Faisal Mahmood

Odense University Hospital (OUH), Dept. of Oncology, Odense, Denmark. University of Southern Denmark, Dept. of Clinical Research, Odense, Denmark

Abstract:

Technological improvements in radiation therapy has enabled dose delivery with very high geometrical precision. Consequently, treatments are safer and more effective, and can be delivered in shorter treatment courses, than earlier. However, lack of response or relapse in some patients, indicate that sole focus on geometrical conformality is suboptimal. In fact, a growing pool of evidence supports the notation that a better integration of the tumour biology is required. Therefore, the research emphasis within the radiation therapy community has recently been turning towards enhancing the biological precision for a heightened level of individualization. The utilization of dose-painting, guided by prognostic and longitudinal imaging biomarkers, represents a cutting-edge approach. This overview focuses on studies using MRI and PET technology, exploring their roles in dose-painting strategies. Special emphasis is placed on the latest advancements facilitated by the integrated MRI-Linac, shedding light on its potential in personalized cancer treatment.

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