Introduction Research indicates that social networks and roles are disrupted throughout the entire trajectory of someone living with a brain tumour. Young adults aged 18–35 years are particularly vulnerable to such disruption because they are in a process of establishing themselves. Pre-existing social roles and support networks of young adults living with a primary brain tumour may change. This study aims to identify the social networks of young adults aged 18–35 years diagnosed with a primary brain tumour and to map how the diagnosis and disease course affects the social network in relation to changes in relationships and roles over time.

Methods and analysis The study adopts a longitudinal design with a convergent mixed methods approach to describe the social network of young adults. The study utilizes a quantitative approach to social network analysis to measure network size, composition and density and a qualitative approach with interviews to gain insight into young adult’s narratives about their network. Network maps will be produced, analysed and all the findings will then be compared and integrated. Interviews and network drawing will take place at the time of the diagnoses, with follow-up interviews 6 and 12 months later. This will shed light on transformations in network compositions and network support over time.

Ethics and dissemination The study has been approved by the Danish Data Protection Agency (ID P-2022-733). Written informed consent will be obtained from all patients. The results will be disseminated through a peer-reviewed journal and reported at local, national and international conferences on brain cancer.