Data resource profile: National Cancer Registry Ireland

Background National Cancer Registry Ireland (NCRI) is the state agency responsible for collecting and analysing data on all cancer patients to help improve health outcomes in Ireland. Established by the Minister for Health under Statutory Instrument 19/1991, it began collecting data in 1994 from both public and private health care providers. Materials and methods NCRI data come from multiple sources, including hospital pathology laboratories, radiotherapy units, medical records, and death certification systems, providing near-complete national coverage and strong longitudinal follow-up. Using internationally recognised coding systems, including International Classification of Diseases for Oncology, Tumour–Node–Metastasis, World Health Organization tumour classification and Australian Classification of Health Interventions, NCRI collects data on patient demographics, tumour characteristics, stage at diagnosis, treatment, and survival. The data undergo rigorous quality assurance procedures to ensure accuracy, completeness, and comparability over time and with international datasets. Results As of March 2026, for years 1994-2025, the NCRI held data on 1 131 145 tumours (International Classification of Diseases, 10th Revision, C00-96, D00-48) diagnosed in 883 967 individuals. An average of 36 078 invasive cancers [including nonmelanoma skin cancer (NMSC)] per year were diagnosed during 2019-2023, accounting for ∼0.75% of the population. The most common tumour sites registered during this period were NMSC, prostate, breast, lung, and colorectal. NCRI demonstrated high data quality, with low levels of death certificate-only cases (<1%), unknown primary sites (1.3%), and unspecified morphology (7.5%) and high microscopic verification (92.3%). Conclusion NCRI is a comprehensive resource for cancer surveillance, service planning, policy development, and research. Enhanced linkages and expansion of data collection would improve NCRI's capacity to inform cancer research, policy development, and evidence-based improvements in cancer care.