Gastric Cancer Recent Epidemiological Trends in a Low-Risk Western Population, A National Cancer Registry Study

Background Gastric cancer (GC) remains a major global health issue. This study examines GC epidemiology in Ireland, focusing on histological subtypes, age distribution, and stage at diagnosis. GC is broadly classified into intestinal-type (ITGC) and diffuse-type (DTGC), including signet ring cell carcinoma (SRCGC). ITGC, often linked to Helicobacter pylori and the Correa cascade, typically has a better prognosis. DTGC, by contrast, is more aggressive, lacks a defined precursor, and tends to metastasise earlier to the peritoneum. Methods We analysed GC cases from the National Cancer Registry Ireland (NCRI) from 2007–2021, using ICD-O3.2 codes for morphology and topography. Staging data from 2014–2019 were also reviewed. Results An average of 447 GC cases were diagnosed annually. Among 6,708 cases, 18% were ITGC, while 20% were DTGC or SRCGC. Notably, 57% were recorded as “Adenocarcinoma Not Otherwise Specified,” indicating a major shortcoming in histological classification within the registry. ITGC was predominantly seen in patients aged ≥65, while DTGC and SRCGC had a significantly higher proportion of patients under 65 compared to ITGC. Most cases were diagnosed at an advanced stage, often requiring multimodal or palliative treatment. Conclusions Findings highlight critical gaps in histological reporting in Ireland, which may hinder service planning and international comparisons. Despite trends elsewhere, ITGC remains as common as DTGC and SRCGC in Ireland, based on the current available data. These results underscore the need for improved cancer data collection and subtype-specific reporting.