Natural History and Predictors of Progression in Gastric Intestinal Metaplasia: An Australian Longitudinal Cohort Study

GOAL: To characterize the burden and progression of gastric intestinal metaplasia (GIM) in the Australian context. BACKGROUND: Gastric cancer (GC) is uncommon in developed countries such as Australia, but is often diagnosed at a late stage, conferring poor prognosis. GIM is a premalignant lesion that can identify patients for endoscopic surveillance, but only a small number progress to dysplasia or GC. Longitudinal data regarding burden and progression of GIM in the Australian setting are lacking. STUDY: Patients undergoing oesophagogastroduodenoscopy (OGD) between January 2010 and April 2023 were retrospectively reviewed to determine the rates of GIM and GC. Among patients with GIM, a detailed file review assessed risk factors associated with progression to dysplasia or cancer, with analysis using delayed-entry survival analysis. The cohort was linked to the state-wide cancer registry. RESULTS: Of 13,987 individuals undergoing OGD, 1320 (9.4%) had histologically confirmed GIM. GIM patients were older (mean: 64.6 vs. 54.0), and more often born outside Australia (64.5% vs. 41.0%), most frequently from Southern Europe, Eastern Europe, or Eastern Asia. GIM was associated with higher progression rates (7.2% vs. 0.5%). To examine the natural history of GIM, 1217 individuals were included in delayed-entry Cox regression (19 progressors and 1198 nonprogressors). In multivariable analysis, family history of GC (HR=4.9) and extensive GIM (HR=8.0) were independently associated with progression. CONCLUSIONS: GIM is frequently diagnosed on endoscopic biopsy in Australia, particularly among migrant groups. It is associated with higher rates of GC. Extensive disease or a family history is the strongest predictor of progression, regardless of country of origin.