Introduction
Gastric intestinal metaplasia (GIM) is a premalignant precursor to gastric adenocarcinoma. There has been limited study of its landscape in the Australian context(1).
Aims & Methods
To characterise GIM and its progression to dysplasia or gastric adenocarcinoma in the Australian context.
A retrospective review was performed, following the clinical course of individuals at a single Australian tertiary centre who underwent index gastroscopy with biopsy between 1 Jan 2010 and 1 Apr 2023. The cohort was linked with the statewide cancer registry (accessed 30 Oct 2024). Patient characteristics between individuals with and without histology-demonstrated GIM were compared using χ2 test and unpaired t-test. Amongst those with GIM, a left-truncated, Cox regression analysis was used to identify factors associated with progression to dysplasia/adenocarcinoma, excluding those with advanced disease or censored within the first 6 months.
Results
During the study period, 13,987 individuals underwent >1 gastroscopy with biopsies. Of these, 1320 (9.4%) had GIM. Individuals with GIM were older (mean 64.6±14.3 vs 54.0±17.3 years, p<0.001), and were more likely born outside Australia (64.5% vs 41.0%, p<0.001). The birth regions enriched in the GIM group were Southern Europe, Eastern Europe and Eastern Asia (21.9%, 14.8% and 7.8% of GIM group, vs 7.9%, 6.8% and 2.6% of non-GIM group). Indigenous Australian background was similar between GIM and non-GIM groups (1.1% vs 1.3%, p=0.543). Individuals with GIM were more likely to be diagnosed with dysplasia/adenocarcinoma (7.2% vs 0.5%, p<0.001).
Among GIM patients, 499 (37.8%) underwent >1 gastroscopy over 6080 patient-years of clinical follow-up within our centre, with a mean follow-up to cancer registry linkage date of 7.3±3.7 years. 1218 cases were included in the delayed-entry Cox regression (20 progressors, 1198 non-progressors). In univariate analysis, the risk of dysplasia/adenocarcinoma increased with positive family history of gastric cancer (HR 8.17, 95%CI 2.94-22.68), extensive GIM involving gastric corpus (HR 10.22, 95%CI 3.88-26.89), incomplete subtype of GIM (HR 6.04, 95%CI 1.76-20.75), and pathologist-grading of severe/extensive GIM (HR 3.75, 95%CI 1.43-9.87). Increasing age (by decade, HR 1.02, 95%CI 0.75-1.41), world region of birth (Australia: HR 0.53, 95%CI 0.18-1.60; Asia: HR 2.03, 95%CI 0.73-5.64; South/East Europe: HR 1.12, 95%CI 0.45-2.78), positive smoking history (HR 0.87, 95%CI 0.35-2.14), positive H. pylori history (HR 0.97, 95%CI 0.38-2.47), and diagnosis of autoimmune gastritis (HR 3.61, 95%CI 0.48-27.06) were not significant risk factors. In multivariable analysis (inputting covariates with p<0.10), positive family history of gastric cancer and extensive GIM remained significant risk factors for progression.
Table 1: Cox regression analysis for progression in GIM
| Variable | Univariate analysis | Multivariable analysis |
| HR | p-value | 95% CI | HR | p-value | 95% CI |
| Male sex | 2.62 | 0.051 | 0.99 – 6.89 | 2.54 | 0.061 | 0.96-6.75 |
| FHx gastric cancer | 8.17 | <0.001 | 2.94-22.68 | 4.84 | 0.010 | 1.47-15.99 |
| Extensive GIM | 10.22 | <0.001 | 3.88-26.89 | 8.11 | <0.001 | 2.92-22.56 |
| Incomplete IM | 6.04 | 0.004 | 1.76-20.75 | 1.63 | 0.505 | 0.39-6.93 |
| Severe IM on histology | 3.75 | 0.007 | 1.43-9.87 | 1.17 | 0.786 | 0.38-3.64 |
CI = confidence interval, FHx = family history, GI = gastrointestinal
Conclusion
GIM was common on endoscopic biopsy in our Australian centre, particularly amongst migrants, and associated with higher dysplasia/adenocarcinoma rates. Regardless of country of origin, the risk factors for progression of GIM in real-world practice mirrored overseas cohorts(2). Gastroenterologists should particularly consider family history of gastric cancer and endoscopic extent of GIM in their assessment.
References
References:
1. Hartley I, Connoley D, Sane N, Hirsch R, Abeywickrama D, Sim N, et al. Gastric intestinal metaplasia: Prevalence in a large Australian center and nationwide survey of endoscopic practice. JGH Open. 2024;8(6):e13115.
2. Gawron AJ, Shah SC, Altayar O, Davitkov P, Morgan D, Turner K, et al. AGA Technical Review on Gastric Intestinal Metaplasia-Natural History and Clinical Outcomes. Gastroenterology. 2020;158(3):705-31.e5.