AB083. SOH25_AB_389. Gastric cancer epidemiological trends in a low-risk western population: a national cancer registry study

Background: Gastric cancer (GC) is a leading cause of cancer-related mortality. It is classified into two subtypes: intestinal type (ITGC) and diffuse type (DTGC), which have distinct clinical behaviours. ITGC is associated with precursor lesions, allowing for potential early detection, whereas DTGC has no precursors, is more common in younger patients and is associated with peritoneal metastases. DTGC has been increasingly observed in Western populations. We assessed GC epidemiological trends in a low-risk Western population.

Methods: We conducted a population-level study using the Irish National Cancer Registry (NCR), analysing epidemiological data from 2007 to 2021. ICD-O3.2 codes were used for morphology and topography classification.

Results: A total of 6,708 GC cases were diagnosed in Ireland between 2007 and 2021. The average annual incidence was 447 cases. Of these, ITGC accounted for 19% (1,231 cases), DTGC (including signet ring cell) for 21% (1,331 cases), and adenocarcinoma not otherwise specified for 60% (3,850 cases). ITGC predominantly affected older patients (76% aged 65+ years old), while DTGC affected a higher proportion of younger patients (46% under 65 years old). Both subtypes were often diagnosed at advanced stages, with 27% of ITGC and 38% of DTGC diagnosed at stage 4.

Conclusions: In Ireland, ITGC and DTGC are equally common, both presenting at advanced stages. This underscores the need for screening strategies and enhanced treatment options, including therapies like intra-peritoneal chemotherapy. Our findings highlight areas for quality improvement in the management of gastric cancer.

Keywords: Gastric cancer (GC); diffuse type gastric cancer (DTGC); intestinal type gastric cancer (ITGC); screening; quality improvement