Background: The purpose of this case study is to describe how a vulnerable group of patients can be included in research. The activities, challenges, lessons learned, and reflections on the importance of patient involvement in research for 5 years (2016–2021) at the adolescent and young adult (AYA) cancer support facility, Kræftværket, are reported. Main body: A patient panel at Kræftværket, the Youth Panel has multiple aims, one of which is the ability to perform patient involvement in research, with the goal of achieving research of high quality. We here describe how Patient and Public involvement (PPI) can be customized to AYAs in a cancer trajectory, who face many challenges, including those in the physical, psychological, and social domains. During 2016–2021, Youth Panel meetings were planned every third month but interrupted during the COVID-19 pandemic. With a flexible structure and a dynamic panel including 10–15 varying AYAs in a cancer trajectory, engagement and involvement have been maintained. Eight research topics were investigated, seven of which were discussed and confirmed to be important by the Youth Panel. Out of eight topics, three were raised by patients, and five by researchers. One was not discussed due to COVID-19. Some of the challenges we have experienced were related to the flexible meeting structure and the differing expectations and priorities as well as the impact of COVID-19. However, we experienced that patient involvement is possible in the field of AYA oncology if a trusting environment is created. A key finding in our case study was, that without a national Danish PPI program and no defined international standard for PPI in AYA cancer research yet, we were able to give patients the possibility to give input to researchers on topics where research is missing. Conclusion: Here, we demonstrate how patient involvement in research has been performed at an AYA cancer facility, Kræftværket, during a 5-year period. We encourage others to perform patient-involving research, even in challenging populations. Ideally this must follow international standards for PPI in AYA cancer research when such exist to improve research with crucial insight from patients.