Abstract
The relatively small number of cancers in the adolescent and young adult (AYA) age group, those aged 15-39 years, does not appropriately reflect the personal and societal costs of cancer in this population, as reflected in the potential years of life lost or saved, the decreased productivity and health-related quality of life due to the impact of the disease during formative years, and long-term complications or disabilities. Improvements in care and outcomes for AYAs with cancer require collaboration among different stakeholders at different levels (patients, caregivers, health-care professionals, researchers, industry, and policymakers). Development of a Core Outcome Set (COS), an agreed minimum set of outcomes that should be measured globally in research and routine clinical practice-specifically for AYAs with cancer-with outcomes that are well defined based on the perspective of those who are affected and assessed with validated measures, is urgently required. A globally implemented COS for AYAs with cancer will facilitate better pooling of research data and the implementation of high-quality health-care registries, which by benchmarking not only nationally but also internationally, may ultimately improve the value of the care given to these underserved young cancer patients. We reflect on the need to develop a COS for AYAs with cancer, the arenas of application, and the challenges of implementing an age-specific COS in research and clinical practice.