By Professor Esther Troost, coordinator of the KAYAC+ Project
Each year, approximately 150,000 adolescents and young adults (AYAs) between the ages of 15 and 39 years are diagnosed with cancer across Europe. This is a distinctly underserved patient population that sits at the intersection of paediatric and adult oncology; as such, many of them face unique biological, psychosocial, and therapeutic challenges. Despite significant advances in oncology, long-term survival rates in AYAs have not improved at the same pace as those that have been observed in children or older adults. Furthermore, 10-25% of treated patients in this group experience recurrence or develop subsequent primary malignancies that are frequently attributable to the long-term sequelae of cancer therapy.
To address these issues, the study entitled Knowledge on outcomes of adolescents and young adults with cancer (KAYAC+) was launched. It is a European research initiative that seeks to generate robust evidence to support the optimisation of radiation therapy strategies for this age group. Funded by nearly €1 million through the European Partnership for Radiation Protection Research (Pianoforte), and supplemented by national beneficiaries, the project will run for 48 months and bring together some of Europe’s most experienced academic centres in particle and photon therapy.
A Complex Cohort with Unmet Needs
Many AYAs present with a diverse spectrum of malignancies, including breast, thyroid, testicular, central nervous system, bone, soft tissue, and haematological cancers. Management typically requires multimodal approaches that combine surgery, systemic therapy, and radiotherapy. Despite aggressive treatment, outcomes remain suboptimal compared with those in other age groups. While the biological basis for this discrepancy is not fully understood, hypotheses include age-specific tumour biology, hormonal and genetic factors, suboptimal adherence to treatment, and heightened susceptibility to late effects, particularly secondary malignancies.
The risk of radiation-induced neoplasms is of particular concern in this cohort due to the long post-treatment life expectancy and ongoing tissue development. Thus, it is essential that we refine radiotherapy modalities to balance tumour control with long-term toxicity reduction.
The Role of Particle Therapy in AYA Oncology
Over the past 15 years, an increasing number of European centres have adopted proton therapy as a clinically viable alternative to conventional photon-based approaches. The distinct physical properties of protons—specifically the Bragg peak—allow for superior dose conformity and greater sparing of healthy tissue, which is particularly advantageous for young patients whom we hope to cure.
Within the framework of KAYAC+, we aim to expand this knowledge base through systematic investigation of treatment outcomes in AYA patients across these multiple European centres. We will explore both clinical endpoints and technical variables that may influence the risks of secondary malignancies and treatment failure, including radiation dose distribution, imaging protocols, and treatment planning methodologies.
Building a European Data Infrastructure
KAYAC+ is not merely a clinical study but also a data infrastructure initiative. Two PhD candidates—based respectively at OncoRay/Faculty of Medicine of TU Dresden, Germany, and the Skandion Clinic/Stockholm University, Sweden—will analyse multicentre data on AYA patients who have been treated with photon or particle therapy. The collected data will form the foundation of a pan-European database—a critical resource for long-term outcomes research in radiation oncology, and a stepping stone towards a future European Particle Therapy Data Warehouse.
Our consortium includes these centres, which have deep expertise in advanced radiation modalities:
- University Medical Center Groningen (UMCG), The Netherlands
- Skandionkliniken Uppsala, Sweden
- Centro Nazionale di Adroterapia Oncologica (CNAO), Pavia, Italy
- IFJ PAN, Kraków, Poland
- Centre Léon Bérard, Lyon, France
- KU Leuven, Belgium
- Danish Center for Particle Therapy / Aarhus University Hospital, Denmark
Together, we represent a pan-European commitment to the advancement of precision radiotherapy and to ensuring that young patients across the continent benefit from the latest innovations in care.
Translating Research into Better Care
We view KAYAC+ as part of a broader vision – as a nucleus for a pan-European database on particle therapy that will include data from nearly all European particle centres . Through rigorous data generation, interdisciplinary collaboration, and sustained clinical engagement, this project aspires to identify modifiable risk factors and therapeutic strategies that will improve not only survival terms but also the long-term quality-of-life for young cancer survivors.
It is our collective responsibility to ensure that AYA patients are no longer a “forgotten middle” in oncology care. By refining our tools, personalising our approaches, and anticipating long-term risks, we can offer this population not only cure, but also the chance to enjoy full and healthy lives beyond cancer.
Prof Esther Troost, MD, PhD
Coordinator of the KAYAC+ Project
Dean, Faculty of Medicine, Technische Universität Dresden
Professor of Radiotherapy
Director, Department of Radiotherapy and Radiation Oncology, University Hospital Dresden
Dresden, Germany
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Introducing KAYAC+: a European initiative to advance radiation therapy for adolescents and young adults with cancer. By building a pan-European data infrastructure, the aim is to improve outcomes and long-term quality of life.