Report on the Tenth Annual Meeting and Workshops of the European Particle Therapy Network

Report on the Tenth Annual Meeting and Workshops of the European Particle Therapy Network

The European Particle Therapy Network (EPTN) was established in 2015 in response to the growing number of particle therapy centres across Europe. It was designated a task force of ESTRO in 2017. On 22 October 2024, the EPTN celebrated its tenth annual meeting at the Medical University of Vienna (MUW). The meeting was preceded by three workshops on 21 October. We extend our gratitude to the MUW for hosting this milestone event. The EPTN is proud to observe the network's steady growth and record-breaking participation in the 2024 Annual Meeting and workshops. This year, the meeting welcomed 73 participants from 13 European countries, while the workshops attracted a combined attendance of 68 participants.

Beyond the expanding attendance at the annual meetings, the EPTN is pleased to note the increased activity of its work packages (WPs), which are conducted chiefly through workshops, publications and events. The sustained interest in these initiatives was evident in the success of the 2024 annual meeting workshops, which were held at a central Vienna venue. WP7 on health economics hosted a workshop titled Cost-effectiveness Research in Proton Therapy: First Attempts, Challenges, and Opportunities. Additionally, WPs 1 and 8 co-organised a workshop on the new and modified content of the EPTN database, building on the establishment of WP 8 (data registry infrastructure) last year. Thirdly, the EPTN adaptive task group, which was formed in 2023, conducted its second workshop on adaptive proton therapy, building on the success of last year’s session.

As in previous years, detailed reports from these workshops were presented during the annual meeting for all participants. The meeting also provided updates on developments in the European particle therapy sector more broadly. While no new particle therapy centres were inaugurated in 2024, several facilities are expected to open in 2025, with new locations planned in Italy, Norway and Spain. The newly restructured EPTN website was presented. It is designed to improve the visibility of the network’s activities, particularly those of the individual WPs. Each WP now has a dedicated section on the website, allowing them to share announcements, publication information, and updates on their initiatives and events. These sections also include details of leadership and organisational aspects, creating a comprehensive and accessible platform for the entire network.

EPTN-related events 2024-25

ESTRO School Hybrid Teaching Course in Particle Therapy: 14 October – 29 November 2024, Heidelberg, Germany.
EPTN WP3 Radiation Therapist (RTT) Workshop: 15 – 16 November 2024, Villingen, Switzerland.
EPTN WP4 Annual Workshop: 21-22 November 2024, Delft, The Netherlands.
FLASH Radiotherapy and Particle Therapy: 4-6 December 2024, Rome, Italy.
ESTRO School Course in Proton Therapy for Children and Young Adolescents: 16-17 January 2025, Essen, Germany.
Paul Scherrer Institute (PSI) Winter School: 12-17 January 2025, Villingen, Switzerland.
ESTRO School Course in Particle Therapy: 23-27 March 2025, Maastricht, The Netherlands.
ESTRO2025 Congress: 2-6 May 2025, Vienna, Austria.
63rd Meeting of the Particle Therapy Co-operative Group: 2-7 June 2025, Buenos Aires, Argentina.

In addition to EPTN-relevant events, the individual EPTN WPs organise multiple internal meetings, both virtually and physically, throughout the year.

One of the aims of the EPTN is to enable the further integration of proton therapy into the radiation oncology community. Consequently, the EPTN presented during the annual meeting its aim to become increasingly involved in more general oncology meetings. The chief intention is to ensure that proton therapy research grows to become ever more prevalent.

EPTN publications 2024

Gomà C, Henkner K, Jäkel O, Lorentini S, Magro G, Mirandola A, Placidi L, Togno M, Vidal M, Vilches-Freixas G, Wulff J, Safai S. ESTRO-EPTN radiation dosimetry guidelines for the acquisition of proton pencil beam modelling data. Physics and Imaging in Radiation Oncology. Volume 31, 2024, 100621, doi: 10.1016/j.phro.2024.100621

Grau C, Dasu A, Troost EGC, Haustermans K, Weber DC, Langendijk JA, Gregoire V, Orlandi E, Thariat J, Journy N, Chaikh A, Isambert A, Jereczek-Fossa BA, Vaniqui A, Vitek P, Kopec R, Fijten R, Luetgendorf-Caucig C, Olko P. Towards a European prospective data registry for particle therapy. Radiotherapy and Oncology. Volume 196, 2024, 110293, doi: 10.1016/j.radonc.2024.110293

European Union/European Investment Bank mapping study on proton centre status and evolution in Europe

By Manfred Newrly

Manfred Newrly, senior sector engineer of the European Investment Bank (EIB) (life science/health department) presented the results of a third-party mapping study regarding the status and evolution of proton centres in Europe.

The study was intended to map proton therapy centres in Europe to update the lending policy and appraisal processes of the EIB regarding proton therapy centre construction and/or extension projects, by providing an in-depth analysis of the sector's development, growth, and challenges across Europe. The EIB, the European Union (EU) bank, which has a yearly financing volume of ca. €88bn, contributed to the financing of four heavy-ion centres between 2003 and 2014 through a total investment of approximately €300m. Lending to any project must follow certain eligibility criteria. As of 2018, further investment in proton therapy centres was stopped because of an internal lending policy update. Since then, the field has been further analysed in conjunction with DG Santé. The analysis includes monitoring how clinical evidence is evolving. The current analysis falls under this ongoing monitoring activity.

The first section of the report from the study focused on the geographical distribution of centres. At the time of compiling the report, there were 27 proton therapy facilities in 13 European countries, and there was a concentration of centres in highly populated regions in predominantly Western Europe. The report estimated that around 4300 adult patients were treated per year in these facilities. At the time of the report, six proton centres were under construction or extension; 13 centres were in the planning stage, nine of which were the result of a donation in Spain. The report also listed a number of facilities that had been closed or paused, mainly for financial reasons.

The report then covered various aspects of proton treatment, which are considered below.

Indications: proton therapy is used primarily for central nervous system (CNS) tumours, head and neck cancers, chordomas, chondrosarcomas and paediatric cases, with indications varying by country (refractory tumours/standard indication/model-based).
Reimbursement: stark differences were found between countries regarding validated indications by cancer type and reimbursement amounts. However, there was uniformity on current main indications throughout Europe (CNS, paediatric, head and neck).
Referral: accessibility/catchment area, integration into medical networks/partnerships, and local governmental support play roles in directing eligible patients to receive optimal therapy.
Human resources requirements: specialised staff requirements, recruitment and training are crucial for effective operation, and collaboration with educational institutions is beneficial.
Technological evolutions: advances in particle therapy (FLASH, boron neutron capture therapy, carbon-ion, e-beam, upright patient positioning) may have an impact on “traditional” proton therapy in the long term.
Costs: significant capital (ca. €45m), financing cost (loans), and operational expenditures lead to financial challenges in times of crisis (COVID) and cost increases (e.g. energy) and frequently require public support.
Clinical evidence: there is a lack of substantial clinical evidence that proton therapy is superior to conventional treatments, so funding and widespread adoption are challenging.
Need for clinical trials: more clinical trials, especially randomised controlled trials, are necessary to build evidence for proton therapy, with international collaboration and funding being key challenges.

Although the EIB has not formally updated its lending policy, it will assess on an individual basis the financing of newly proposed heavy-ion projects. There will be a focus on aspects such as public support/government health care strategy, financial solidity (reimbursement/referral), catchment area, clinical research component, solid staff availability/operational/technological planning, etc.

Collaborative projects

PROTECT

By Hanna R. Mortensen

The PROTECT randomised trial is examining proton vs. photon therapy in the trimodality treatment of oesophageal cancer. It has been set up to generate evidence for the use of proton therapy in collaboration with the EU and industry.

The study involves 19 public and industry partners, with the aim of comparing the clinical outcomes for patients treated with proton or state-of-the-art photon chemo-radiotherapy for locally advanced oesophageal cancer. Multiple WPs are focused on radiotherapy and surgery quality assurance (QA), public and patient involvement, health economics, translational studies, and novel trial methodologies, in a collaboration that involves partners and scientific societies such as ESTRO and EPTN.

The trial has been initiated in Denmark, Belgium, Germany and Switzerland, and more than 50 patients have been randomised. Additional centres in Italy and France are expected to start recruiting soon, and the study is still open for more centres to join.

HITRIplus

By Sandro Rossi

The heavy ion therapy research integration (HITRIplus) project is led by the Centro Nazionale di Adroterapia Oncologica (CNAO, the National Centre for Oncological Hadron Therapy) and was described during the EPTN annual meeting by project coordinator Sandro Rossi. It is a collaborative initiative that is focused on advancing heavy-ion therapy in Europe. This effort brings together 23 institutions, including cancer treatment centres, research institutions, universities, and small-to-medium-sized enterprises, across 14 European countries. The project started in April 2021 and is set to run until September 2025, with potential extension requests up to March 2026.

In its first three years, HITRIplus has achieved all its key milestones, which were: to improve access to heavy-ion therapy throughout Europe, to develop compact and cost-effective treatment technologies, and to support innovative research in particle therapy. HITRIplus has organised effective outreach and training efforts, and has fostered a global network of medical and scientific professionals through webinars, seminars, and social media. Over 1500 participants have engaged in its specialised training programmes, forming an international community that is dedicated to advancing hadron therapy. HITRIplus is also collaborating closely with industry and has identified 12 high-priority technologies that can be commercialised, so ensuring that scientific advancements translate into practical tools for clinics.

An important component of the project is its educational WP, which provides comprehensive, globally accessible courses on heavy-ion therapy through online modules. The transnational access programme has enabled researchers to access HITRIplus accelerator centres, which offer 222 hours of beam time for experimental research and facilitate clinical experience and research for 24 medical teams. Engineering and technology design have seen significant progress as well. For example, a compact carbon-ion accelerator design was developed with a unique magnet configuration. This design supports both the emerging FLASH therapy and a range of energies for highly targeted cancer treatment.

HITRIplus is also exploring new treatment possibilities. It has developed an innovative upright treatment chair that facilitates flexible beam angles, enabling more precise targeting without the need for costly gantries. Other achievements include the development of a control system designed to deliver multi-energy treatments at increased speeds, hence integrating advanced computing for continuous operation. To ensure consistency across research centres, HITRIplus has standardised radiobiological experiments by instituting a unified protocol for biological and dosimetry measurements, which enables more reliable data comparisons that are crucial for cross-centre scientific collaborations.

EU-MSCA-ITN RAPTOR project

By Francesca Albertini

The EU-Marie Sklodowska-Curie Actions innovative training networks (EU-MSCA-ITN) project on real-time adaptive particle therapy treatment of cancer (RAPTOR) is a collaborative research initiative that involves 15 PhD students from various European institutes. These students are united by the goal of advancing online adaptive particle therapy (OAPT) to improve patient outcomes. The project, which began in March 2021 and is supported by a €4m fund, will run until August 2025. It has made significant progress in developing this innovative treatment approach. However, it has also faced challenges that other EU-MSCA projects should consider, particularly regarding funding and the timing of PhD student involvement.

One of the key lessons learned during the project is the difficulty in securing adequate funding for PhD students over the full duration of their involvement. While the EU-MSCA funding covers 36 months, the extensive secondments to partner institutes and the numerous training events—essential components of the EU-MSCA programme—have disrupted the students' research time. This has made it challenging for them to complete their PhDs within the funded three-year periods.

Despite these challenges, the RAPTOR project has achieved significant milestones. As of now, 85% of the project’s deliverables and milestones have been successfully completed, and the dissemination of research has been highly successful. The project has produced 25 peer-reviewed manuscripts, and the RAPTOR students have been active in sharing their work at international conferences. In 2024 alone, the students presented 18 oral presentations at leading conferences, thereby demonstrating the impact and visibility of the project.

A major achievement was the successful clinical implementation of the OAPT workflow in October 2023. This marked the first patient treatment at the PSI through the use of this workflow, proving that OAPT can be delivered efficiently in a clinical setting while ensuring patient safety and without extending the treatment time compared with traditional, non-adaptive treatment slots (10.1088/1361-6560/ad7cbd).

Over these years, three training schools have been organised. These schools have benefited not only the RAPTOR PhD students but also have provided essential training for other students on key steps in the adaptive workflow. In October 2024, the project reached a significant milestone: the final conference, which was held in Dresden, Germany. At the conference, the 15 PhD students presented the results of their work, showcasing significant advancements in the field of OAPT. The project has also strengthened collaboration among research institutions, with 13 multi-institutional manuscripts fostering continued comparison of methodologies.

Workshop reports

Adaptive particle therapy

By Francesca Albertini, Rita Simoes & Pieter Populaire

The EPTN adaptive particle therapy (APT) task group was established in October 2023. Over the past year, two tasks were prioritised: the performance of a strengths, weaknesses, opportunities and threats (SWOT) analysis and provision of recommendations on commissioning and QA. On 21 October, 2024, a workshop was held that enabled an in-person discussion focused on the progress of these two tasks. We thank all the participants in the workshop for their active participation.

To enhance communication, priority was placed on standardising definitions for various types of APT. Differentiation criteria included (a) the rationale for adaptation (e.g., anatomical changes, tumour response), (b) adaptation timing (e.g., scheduled versus triggered), and (c) adaptation timescale (e.g., offline versus online). Workshop consensus indicated that current definitions are sufficient, with no further modifications suggested. Efforts are underway to consider the publication of these standardised definitions as formal recommendations.

The SWOT analysis provided valuable insights into the status of OAPT. Prior to the workshop, 17 participants had engaged in a preparatory phase, initially submitting individual assessments of OAPT’s SWOTs. These inputs were then synthesised by two subgroups, which were focused respectively on strengths and weaknesses (SWs) and opportunities and threats (OTs). The consolidated findings were presented at the in-person workshop and visualised on a Miro board. All SWOT elements were categorised into seven key topics: imaging, contours, automated workflow, time, RTT-driven workflow, dose/toxicity, and novel treatment concepts.

Discussions at the workshop reinforced the hypothesis that OAPT enables the use of advanced treatment strategies, such as dose escalation and adaptive fractionation, which significantly expand the potential of proton therapy, particularly for non-responsive tumours. For broad adoption, regulatory-approved, ready-to-use workflows and a consistent RTT-driven approach with well-defined training and responsibility protocols are essential. Notably, no major technical threats were identified, and this indicated the feasibility of large-scale implementation, although challenges remain concerning time, cost, and RTT workflow adaptation. Key opportunities include enhanced dose distribution with reduced side effects and the potential to develop new treatment approaches, setting OAPT on a path to elevate clinical practices in particle therapy.

The preliminary findings will be submitted as an abstract to the upcoming ESTRO conference (May 2025), pending a full-length manuscript later that year.

The last part of the workshop was focused on commissioning and QA in OAPT. Twenty people had confirmed their prior interest in this task and an internal survey was used to assess current practices across centres (adaptation in photons or protons; online or offline). Herein the integration and QA of subsystems such as imaging, motion management, and treatment planning were emphasised. During the workshop, major discussions highlighted the need for comprehensive commissioning protocols to ensure cohesive system functionality, accurate real-time dose calculations, and effective motion management in response to anatomical shifts. Two subgroups have been formed, one emphasising commissioning and acceptance and the other targeting QA. The expected outcome of this task will be an ESTRO-supported recommendation (estimated for the end of 2025). Alignment with the online adaptive XT guidelines that are in the making is taking place.

New and modified content of the EPTN database

By Karin Haustermans & Hans Langendijk

The day before the EPTN meeting in Vienna, a workshop within the framework of WP1 was organised. The topic of this workshop was the creation of new and modified content for the EPTN database.

General objectives
The general objectives of this project are to establish a multi-centre database on a European level to support the evidence-based introduction of particle therapy.

WP1 is responsible for the content of this database.
WP8 is responsible for the creation of the infrastructure of this database.

Specific objectives

The specific objectives of the database are:

to report the outcomes of the use of particle therapy, including real-world data on efficacy, toxicity, quality of life and cost-effectiveness;
to generate hypotheses for future clinical trials;
to create healthcare learning systems (e.g. dose optimisation based on normal tissue complication probability models);
to use it as a basis for phase IV studies; and
to function as an alternative for clinical trials, especially in rare diseases.

EPTN data registries

The first EPTN data registry (2019) consisted of a generic set of items. Additional items were included later for specific subsites (e.g. CNS, head and neck, prostate…).

For paediatric patients, it was decided not to create a separate EPTN database, as there is an existing database specifically dedicated to paediatric patients, called HARMONIC. Therefore, the EPTN database is focused exclusively on adults (18 years or older).

At the EPTN 2023 meeting in Manchester, UK, it was decided that the data items should be updated, and this led to the creation of EPTN Data Registry Version 2.

The structure of the registries has been revised. There remains a generic tumour site-agnostic data set, which is now divided into different anatomical subcategories:

head: CNS + base of skull and head and neck registries already exist but require updates. A new registry for the eye needs to be created;
thorax: existing data sets for lung, oesophagus, and breast cancer need to be updated;
abdomen: no registries exist. New registries for liver and pancreas cancers will be created;
pelvis: only a prostate cancer registry exists. Three new registries will be created: one for ano-rectal cancer, one for gynaecological cancers, and one for seminoma; and
all over: a data set for sarcoma should be developed.

Items levels
Different levels in the database were defined.

Level 1 = minimal data set: mandatory data that should be registered for all patients, collected on a routine basis.
Level 2 = extended data set: data collected on a routine but not mandatory basis.

Level 2a = minimal data set collected on a routine basis to be compulsorily registered when feasible.
Level 2b = an extended data set that can be filled in on an optional basis, but which also contains routine data collected.

Level 3 = research data set within the framework of clinical trials.

Workshop
At the workshop, subgroup leaders for the different anatomical sites came together from different proton therapy centres in Europe (see table below). During the workshop, it was decided to focus on levels 1 and 2a. These two levels will then form the basis for a data set in the database infrastructure (which is part of WP8).

EPTN data registry update (2024)

For the existing registries, the workshop members:

reassessed the level 1 items;
checked with the generic registry to avoid any overlap;
added new items based on new insights;
modified existing items;
deleted unnecessary items; and,
coordinated with the other subgroups within the anatomical region.

For new registries, the members:

defined the level 1 items;
checked for overlap with the generic registry; and,
coordinated with other subgroup leaders of the anatomical regions.

Discussion points

What should be included in the generic assessment, which will be the first part of the database. The purpose of the generic assessment is to provide an annual report on the number of patients treated with proton therapy in Europe, the indications, the percentage of patients included in trials, etc.
Whether only proton therapy patients should be included in the database or also patients treated with photons. To avoid the risk of bias, it was decided that it would be interesting to also include photon patients.
Decide how to deal with the different versions of the common terminology criteria for adverse events, quality of life questionnaires, tumour, mode, metastasis versions, and coding according to the international classification of diseases. The preference was that the database should be up-to-date.
Which dose parameters should be collected? Within the different subsites, different dose parameters are collected. It was agreed that these should be harmonised and should probably be part of the generic items.
Decide how to collect the dose parameters: in a tabular format, or as the real dose-volume histograms? It was decided that, if possible, the latter was to be preferred. It was decided to set up a small subgroup that would include physicists and physicians, to define those parameters and to discuss with the International Commission of Radiation Units and Measurements report committee on proton therapy.
Level 2a items: patient-reported outcome measures, toxicity in the long term, and cost-effectiveness.
What about re-irradiation? Currently, we have very limited items in the generic data set that refer to re-irradiation. We also decided that we should connect to ReCARE (a cohort within E²-RADIatE) to synchronise item collection, and that we must add more specific items into separate registries or per tumour site or per anatomical region.

The next steps

To establish a new minimal data set for generic assessment and all relevant tumour sites, with a target deadline of December 2025.
To come up with white papers, a general paper with the generic assessment and maybe also separate papers per anatomical site or per tumour site, with a target deadline of June 2025.
The start of the building of the infrastructure (WP8) is planned for December 2025 and again will start with the generic assessment.

Subgroup leader	Affiliation	Subgroup
Karin Haustermans/ Hans Langendijk	Leuven/ Groningen	Generic
Carola Lütgendorf-Caucig	Wiener Neustadt	CNS
Barbara Bachtiary	Villigen	Base of skull
Kenneth Jensen	Aarhus	Head and neck
Coen Rasch	Leiden	Eye melanoma
Maaike Berbee	Maastricht	Oesophagus
Crispin Hilay	London	Lung
Marta Scorsetti/ Davide Franceschini	Milan	Breast
Hanna Rahbek Mortensen	Aarhus	Upper gastro-intestine
Jiri Kubes	Prague	Prostate
Marianne Guren	Oslo	Lower gastro-intestine
Asma Sarwar	London	Gynaecology
Stijn Krol	Delft	Seminoma testis
Simona Gaito	Manchester	Lymphoma
Maria Rossaria Fiori	Pavia	Sarcoma

Cost-accounting and cost-effectiveness research

By Hedwig Blommestein and Yolande Lievens

The aim of this workshop was to provide insight for attendees into the broader health technology assessment (HTA) framework, its application to proton beam therapy (PBT) and to share current research initiatives. During the workshop, there was a particular focus on cost accounting and cost-effectiveness research.

The workshop started with Yolande Lievens providing a context regarding the previous history of EPTN-WP7. The aim is to build economic evidence on PBT, keeping in mind the costing research that has already been performed in photon therapy, including the time-driven activity-based costing (TD-ABC) model of the ESTRO-health economics in radiation oncology (HERO) project. In the early days of WP7, data generation proved difficult, as many centres were still in the planning or start-up phase and this hampered surveying of economic parameters, and clinical evidence was not yet available. She introduced the renewed collaboration on health economics, with new research initiatives in relation to EPTN-WP7.

Hedwig Blommestein provided an introduction to the broad HTA framework and the steps in economic evaluations. The generic outcome measures in economic evaluations were discussed and their link to radiotherapy outcomes (i.e. toxicities). The timing of HTA (i.e. the moment at which the assessment is conducted) can be challenging due to a learning curve, changing patient numbers over time and incremental innovations.

The workshop continued with a detailed presentation on cost accounting in radiotherapy by Professor Lievens. Methods for costing and challenges in radiotherapy were discussed; the latter included the learning curve, economies of scale and timing of evidence generation. The presentation concluded with a detailed explanation of the HERO TD-ABC model for photon radiotherapy.

An example of early HTA of PBT in uveal melanoma was presented by Diego Larrotta-Castillo. He illustrated how tools from HTA could help to demonstrate the potential cost-effectiveness of a new technology at an early stage as well as to highlight current research gaps and areas for future research. Crucial parameters for which future research is highly recommended were (economic) effectiveness estimates (e.g. generic health-related quality of life).

Then Yaqeen Shanti presented the first results of a survey on PBT. The aim of the survey is to support the development of a European TD-ABC model for PBT. Alignment with the photon ESTRO-HERO model is crucial, to allow cost comparisons between photon and proton treatments. During the workshop, speakers and attendees discussed the level of detail that was required for the costing model, and the next steps in the roll-out of the survey.

The participants drew some conclusions:

not all aspects of the broad HTA framework are currently covered. Examples of understudied topics include accessibility, organisational aspects and the patient perspective;
HTA requires data, and within the ESTRO community we need to ensure that these data are collected. Given the focus on incremental differences in cost-effectiveness research, collecting data on costs and outcomes is crucial for both intervention (proton) and comparator (photon) technologies; and
since outcomes and costs are dynamic, continuous assessments and incorporation of most recent evidence are required.

We welcome a broader group of researchers to strengthen the collaboration in EPTN-WP7.

Concluding remarks

The EPTN is very happy to see that participation is growing, both in the annual meetings and the workshops as well as within the broader network. We are particularly excited to have celebrated the tenth anniversary and look forward to another productive and impactful decade. The reorganisation and establishment of new WPs is a strong sign of the evolution of the network in terms of membership and engagements. The continued activities of the WPs, individually and jointly, are particularly encouraging, and we look forward to the upcoming events and publications that will show the importance and impact of this network.

Thank you to everyone who has supported the EPTN this year and previously, and for participating in yet another productive annual meeting and workshops.

We hope for a successful new year as we step into the second decade of the EPTN, and look forward to the eleventh EPTN annual meeting, to be hosted in the autumn of 2025.

Damien Weber, Cai Grau, and Dietmar Georg
Co-chairs of the EPTN

Damien Weber, Switzerland

Cai Grau, Denmark

Dietmar Georg, Austria