From “Black Box” to Learning System: Formative Viewpoint on Digital Health Governance for Childhood Cancer Information in Japan

Japan has universal coverage and designated pediatric oncology centers, yet the childhood cancer information ecosystem remains a "black box." The incidence is measurable, but treatment exposure and long-term follow-up are not reliably linked across hospitals, registries, and survivorship services. The World Health Organization (WHO) CureAll framework highlights information governance as a lever for equity. This study aims to propose a formative design for national digital governance connecting registries, clinical systems, and survivorship in Japan. We synthesized international guidance and Japanese statutes, plans, and registry reports. Drawing on operational experience, we specified a minimal pediatric dataset, an HL7 Fast Healthcare Interoperability Resources (FHIR)-based interoperability architecture, and governance to align standards, consent, and data use. No new empirical data were collected. We outline a 4-layer architecture. Source systems (electronic health records, laboratory and radiology systems, pathology, and cooperative group databases) feed an HL7 FHIR gateway. A national Pediatric Data Steward governs standards and interoperability (FHIR profiles and application programming interfaces), terminology and coding (International Classification of Diseases for Oncology and International Classification of Childhood Cancer, with mappings to Systematized Nomenclature of Medicine-Clinical Terms and Logical Observation Identifiers Names and Codes), privacy and consent, data-use agreements, data quality, and audit. Outputs flow to the National and Hospital-based Cancer Registries and a patient-facing Digital Survivorship Passport, with bidirectional clinic updates and linkage to the resident registry and vital statistics. Security, audit, and public reporting span all layers. We define pediatric indicators and a staged road map. Transforming Japan's pediatric oncology information into a learning system is chiefly a governance task. A Pediatric Data Steward, a harmonized pediatric data dictionary via FHIR, and a portable survivorship passport with layered consent can improve timeliness, completeness, follow-up, and transparency.