ESTRO 2023 - Abstract Book

S422

Sunday 14 May 2023

ESTRO 2023

Conclusion Compared to standard care for breast radiotherapy, the person-centered RTT model significantly improved patients’ procedural concerns, overall satisfaction and experience with care. Future refinements in education content or RTT-patient communications should be considered in an effort to resolve patients’ psychological concerns and anxiety. In addition, having one or a few RTTs specialized in person-centered practice could facilitate an individualized approach to patients most in need.

Award Lecture: C Regaud Award

SP-0513 M. Guckenberger Switzerland

Abstract not available

SP-0514 Integrated imaging and biological approaches for next-generation immuno-radiotherapy combinations E. Deutsch 1 1 Gustave Roussy, Radiation Oncology, Paris, France Abstract Text “Immuno-radiotherapy” has recently appeared as a highly promising way to enhance immunotherapy efficacy, based on the fact that radiation therapy (RT) locally induces immunogenic cell death and therefore, could lead to a tumour-directed immune stimulation. For now, and despite preclinical evidences of a synergistic action, few of these immuno-radiotherapy approaches have succeeded to provide significant proof of benefits in the clinical setting, possibly because of the known deleterious effects of RT on lymphocytes. Indeed, we presume that to be efficient, the ‘radiotherapy’ part of immuno-radiotherapy regimens needs to be designed as the best immune-sparing treatment plan to allow further tumour-directed immunostimulation, e.g., using immune-checkpoint blockers. Therefore, the next-generation immuno-radiotherapy schemes will have to integrate novel constraints that preserve lymphocyte-rich tissues to reduce the risk of RT-induced lymphopenia and immunosenescence. More broadly, a drastic effort is needed to upgrade image-based tumour delineation for RT planning, as of today, the routinely-used principles of GTV, CTV and PTV consider uncertainties in planning and treatment delivery, incorporating margins for sub-clinical disease spread that cannot be fully imaged. This implies negative effects on surrounding healthy tissues – including circulating blood – without any clear benefit on tumour control, while it clearly impacts negatively immune cells. We plan to introduce a game-changing immuno-radiotherapy paradigm by integrating into the routine four main exploration axes: i/ leveraging the latest advances in digital pathology for precise image-based tumour volume delineation, ii/ defining an immune organ at risk to be integrated in dose prescriptions,