ESTRO 2025 - Abstract Book

S160

Invited Speaker

ESTRO 2025

Department of Radiation Oncology, Massachusetts General Hospital & Harvard Medical School, Boston, USA

Abstract:

Treatment planning volumes such as "gross tumour volume", "clinical target volume" and "planning target volume" have been fundamental to the way cancer patients have been treated for decades. As the accuracy of dose delivery has improved tremendously, the effectiveness of these planning volumes in ensuring the optimal trade-off between tumour coverage and healthy tissue sparing has been questioned. Recently, the research community has proposed alternative definitions of target volumes, namely probabilistic target maps. How can probabilities be used to prescribe dose? Is there an advantage to using probabilities to guide trade-offs? What are the necessary conditions for translating these concepts into clinical practice? This presentation will address some of these questions. We will review the basic concepts underlying the probabilistic target map. Our main focus is on the clinical target map, which attempts to translate prior knowledge of microscopic tumour infiltration, such as histopathological data, into probability maps as an alternative to the clinical target volume. We review the proposed use of probability maps in treatment plan optimisation. Most studies have used probabilities as voxel-wise importance weights. The question is whether such a simplistic implementation is optimal, or whether more is required for clinical translation. We identify common pitfalls to avoid when implementing probability maps and provide guidance on the steps that need to be taken to ultimately deliver on the promise of the probabilistic approach.

5020

Speaker Abstracts How does climate change impact cancer care? Katie Lichter Department of Radiation Oncology, University of California San Francisco, San Francisco, USA

Abstract: Climate change is an emerging and increasingly urgent challenge to global health, with direct and indirect consequences for cancer care. As extreme weather events become more frequent and environmental shifts impact healthcare infrastructure, the ability to deliver high-quality, uninterrupted oncologic care is at risk. This talk will explore the multifaceted ways in which climate change affects cancer treatment, with a particular focus on radiotherapy, patient outcomes, and global health equity. 1. Introduction: Climate Change as a Public Health Crisis The healthcare sector is both affected by and contributes to climate change. Rising global temperatures, shifting weather patterns, and increasing natural disasters pose threats to healthcare access, treatment delivery, and patient outcomes. Cancer care, which often requires long-term, resource-intensive treatment plans, is especially vulnerable. 2. Global Radiotherapy and Energy Dependence Radiotherapy is a critical component of cancer treatment, but its accessibility and reliability are often dependent on stable energy sources and infrastructure. This talk will highlight findings from my previous research demonstrating how: • High energy dependence in radiation oncology makes it particularly susceptible to power disruptions. • Low- and middle-income countries (LMICs) face disproportionate risks due to unreliable electricity grids and infrastructure limitations. • Decarbonizing radiation oncology must be balanced with maintaining high-quality, equitable access to care.

3. The Impact of Extreme Weather Events on Cancer Care