Portuguese National Cancer Registry: from local registries to high-quality nationwide real-world data.

BACKGROUND: Portugal's population-based cancer registries have evolved from fragmented municipal initiatives, starting in 1976, to full national coverage by 2007, culminating in the legislative creation of the National Cancer Registry [Registo Oncológico Nacional (RON)] in 2017. PATIENTS AND METHODS: This short communication describes RON's structural evolution, data quality, research utility, and readiness for international reporting. RESULTS: Although regional registries captured 20 core epidemiological variables, RON introduced >30 new clinical variables aligned with European Network of Cancer Registries recommendations, refining tumor characterization and treatment details. Analysis of 2022 data reveals that core incidence variables are 100% complete, with microscopic verification (97.8%), death certificate only (<0.1%), and unknown basis of diagnosis (<0.1%) meeting international benchmarks. However, challenges persist: stage is missing in 40.4% of cases, ill-defined morphology or topography affects 3.5%, unrelated surgical codes affect 14.9%, and poor stage standardization is evidenced by 779 recorded options. Despite partial automations, manual data entry remains substantial, contributing to a 3-year publication lag. Nevertheless, RON has supported 56 national and international studies since 2018, with data now sufficient for consideration in international reports. CONCLUSIONS: Portugal has achieved remarkable progress in establishing a comprehensive national cancer registry with robust core data quality and growing international recognition. Strategic investments in automated data integration, real-time validation, targeted training, and phased data release, building on existing European collaborations, will further strengthen RON as a timely, high-impact resource for real-world oncology research and policy.