Since its launch in 2020, the GA4GH Cancer Community of Interest (CoI) has brought together global stakeholders in cancer genomics. However, to date, much of the engagement has centred around presentations and updates from participating groups, rather than coordinated efforts to identify shared challenges, implement GA4GH standards, or define collective priorities for the cancer genomics community. This session will serve as a structured reboot: a participatory workshop to reimagine the Cancer CoI’s value, purpose, and outputs. We will ask hard questions: What are the barriers to uptake of GA4GH standards in cancer genomics? Where are the critical gaps GA4GH can help fill? How can we mobilise this community to prioritise and implement shared use cases? Participants will help co-design a refreshed strategy, including specific goals, engagement formats, and mechanisms for surfacing and advancing cancer-specific interoperability needs through GA4GH.