Understanding the clinical significance of variants associated with hereditary cancer risk requires access to a pooled data resource or network of resources-a "cancer gene variant commons"-incorporating representative, well-characterized genetic data, metadata, and, for some purposes, pathways to case-level data. Several initiatives have invested significant resources into collecting and sharing cancer gene variant data, but further progress hinges on identifying and addressing unresolved policy issues. This commentary provides insights from a modified policy Delphi process involving experts from a range of stakeholder groups involved in the data-sharing ecosystem. In particular, we describe policy issues and options generated by Delphi participants in five domains critical to the development of an effective cancer gene variant commons: incentives, financial sustainability, privacy and security, equity, and data quality. Our intention is to stimulate wider discussion and lay a foundation for further work evaluating policy options more in-depth and mapping them to those who have the power to bring about change. Addressing issues in these five domains will contribute to a cancer gene variant commons that supports better care for at-risk and affected patients, empowers patient communities, and advances research on hereditary cancers.
Keywords: data resources; data sharing; equity; hereditary cancer; human genetics; privacy and security.