From Discoverable to Fit-For-Purpose: Measuring the Impact of Health and Oncology-Specific Metadata Within the Context of the EHDS

Creating high-quality cancer research data is resource-intensive, and maximizing its reuse requires both interoperability and interpretability. Within the context of the emerging European Health Data Space (EHDS), standardized metadata based on Health DCAT-AP offers a foundation for discoverability, but its effectiveness in enabling researchers to assess whether data are fit-for-purpose remains largely untested. This study evaluated the practical usability of Health DCAT-AP for oncology research by analyzing nine real data requests submitted to the Netherlands Cancer Registry. Requests were categorized as uncomplicated, complex, or rejected, reflecting different levels of metadata adequacy and interpretability. Results show that Health DCAT-AP is sufficient for uncomplicated requests using standard classifications (e.g., ICD-O-3), but less effective for complex studies involving rare cancers, long-term follow-up, or multi-source linkages. Dialogue with data holders remains essential. We identify areas where oncology-specific metadata extensions could improve clarity: particularly in cohort definition, linkage feasibility, and follow-up completeness, and propose alignment with EU-wide metadata governance to ensure sustainable, interoperable, and FAIR oncology data reuse across member states.