Chairs: Heidi Lyng (Norway), Xuanfeng “Leo” Ding (USA), Franziska Eckert (Austria), Brita Singers Sørensen (Denmark), Stefan Both (The Netherlands), Stewart “Mac” Mein (Germany/USA)
Invited speakers: Martin Pruschy (Switzerland), Di Yan (USA), Eirik Malinen (Norway), Pierre Montay-Gruel (Belgium), Christian Karger (Germany)
Motivation
There is an increased interest for hypofractionation and ultra-hypofractionation in radiotherapy (e.g., SBRT & SRS using photon-based therapies). For some treatment sites, hypofractionation is becoming the standard of curative care when feasible, offering potential advantages such as improved patient convenience, cost-effectiveness, radiobiological efficiency, increased immune response and possible interaction with systemic treatment (e.g. immunotherapy). However, its application to the fullest extent is challenging due to the need to balance tumor control with the risk of acute and late toxicity. Awareness of biological and physical factors that together influence this balance is crucial for the design of optimal treatment plans. More research on this topic is needed and a common understanding among biologists and physicists would help to advance the field and facilitate clinical translation.
In this joint physics-biology workshop, Challenges and Opportunities in the Era of Hypofractionation will be explored covering a broad spectrum of topics, including tumor and normal tissue responses to high versus low fraction doses (tolerance, recovery, acute/late effects), optimal fractionation schemes, biological modeling, clinical outcome and the role of emerging technology and treatment delivery strategies. Notably, particle therapy, using e.g. protons and carbon ions, has been gradually adopted into clinical practice for certain treatment sites and there is an increasing motivation to adopt hypofractionation in the context of improved efficacy, efficiency, patient comfort/satisfaction, increased patient access to particle therapy and cost effectiveness. However, in particle therapy especially, there are many unknowns in terms of physics, biology, and clinical aspects. These unresolved questions and challenges require discussion and consensus from the scientific, industry, and clinical communities on how to routinely and efficiently implement hypofractionation for photon and particle therapy that is safe, effective, and precise for broad clinical indications.
This multidisciplinary workshop functions to identify and translate radio-biological and physics needs to accelerate hypofractionation treatment regimen to the clinic. The workshop will be divided into three main subtopics:
Subtopic #1: Tissue Responses in Hypofractionated Photon Radiotherapy
Goal: Review biological and clinical outcomes from conventional photon radiotherapy to establish a consensus for clinical implementation.
· Review the radio-biology of hypofractionation
o Tumor responses to higher doses per fraction
o Early and late side effects — incidence/severity of acute reactions and long-term complications/toxicity risks
· Clinical outcome data: conventional versus hypofractionation
· Review of physics and technology development that enables the precision required for hypofractionated treatment
· Challenges in modeling hypofractionation (e.g. EUD, EQD2 estimations)
· Consensus and guidelines based on current evidence for site-specific indications
Subtopic #2: Hypofractionation with Particle Therapy
Goal: Examine the data on particle therapy (proton, carbon, etc.), address challenges in the RBE model and suggest directions for future research.
· Review particle therapy and hypofractionation clinical outcome data
· Status of RBE: experimental and clinical data
· Challenges in treatment planning, biological modeling and delivery
· Future direction for R&D to enhance efficacy and safety
Subtopic #3: Emerging Technologies for Hypofractionated Radiotherapy
Goal: Explore new technologies and treatment techniques for hypofractionation treatment. Assess challenges and opportunities for biological and clinical outcome modeling.
· Emerging technologies: spatial fractionation, Arc, FLASH, functional imaging or biomarker guidance, adaptive therapy and motion management, etc.
· Biological modeling and clinical outcomes: evaluate how these technologies could improve patient care
· Possible combination treatments with biological therapies (e.g. immunotherapy)
· When physicists meet biologists: enabling a high dose conformity and accurate treatment delivery in combination with biological guided therapy in the era of hypofractionation
Outcomes
The outcomes of this workshop are as follows:
· Connecting the international scientific community spanning the academic, clinical and industry space interested in hypofractionation
· Create an environment for interdisciplinary discussions of physicists, biologists and clinician scientists to identify research interests and requirements for the implementation of hypofractionation regimens
· Identify key questions for the topic and recommendations for research to collect data to answer these questions
· Establish an international expert group to write a white paper covering the discussed topics and outcomes from the workshop. The white paper will address key issues and challenges identified during the workshop and provide a potential roadmap for clinical translation of hypofractionation regimes and delivery strategies
· Report findings and next steps from the workshop at the ESTRO annual meeting in 2025
Applicant Eligibility: Radiation biologist, physicists and physician scientists (with physics or biology focus) at all levels of their academic career (from students to senior scientists).
Programme
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Day 1
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Friday 18 October
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09:00-09:15
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Introduction of the workshop
All participants together
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09:15-10:00
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Opening lecture
Standing on the shoulders of Marie Sklodowska-Curie: How Basic Nuclear Physics Research Can Drive Innovations in Medical Physics and Radiation Oncology
Prof. Renata Kopeć
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10:00-10:30
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Coffee break
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10:30-12:30
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Subtopic #1: Tissue Responses in Hypofractionated Photon Radiotherapy
- The Radiobiology of Hypofraction
- Online Assessment of Tumor Treatment Response to Promote Tumor Local Hypofractionation
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12:30-13:30
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Lunch
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13:30-15:00
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Subtopic #2: Hypofractionation with Particle Therapy
- RBE of particles: what can we learn about hypofractionation
- Emerging Technologies for Precise Hypofractionation in Proton Therapy
- Rationale, Clinical Requirements, and Early Experiences with Proton Hypofractionation
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15:00-15:30
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Coffee break
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15:30-17:30
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Subtopic #2: Hypofractionation with Particle Therapy
- Development of DynamicARC therapy - opportunities and challenges in hypofractionation
- Clinical benefit of hypofractionation in the thoracic region
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18:00-20:00
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Social Event
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Day 2
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Saturday 19 October
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08:00-10:00
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Subtopic #3: Emerging Technologies for Hypofractionated Radiotherapy
- Hypofractionated radiotherapy: the potential role of spatial fractionation
- FLASH for Hypofractionated Radiotherapy
- Hypofractionation in heavy ion therapy: multi-ion and arcs
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10:00-10:30
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Coffee break
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10:30-12:30
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Group discussion and plan for the future e.g. consensus paper, research collaboration. Etc.
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12:30-13:30
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Lunch
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13:30-14:30
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Discussion of next steps; take home messages; identify open issues for further research
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14:30-15:30
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Wrap up: Highlights and plan the next steps for the different workshops.
All participants together
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15:30-15:45
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Closing
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