Incidence of Gastric Adenocarcinoma in Those With Gastric Atrophy: A Systematic Review.

Gastric atrophy (GA), or atrophic gastritis, is a pre-neoplastic lesion of gastric cancer (GC). It is part of the Correa cascade, which culminates in intestinal-type gastric adenocarcinoma. The cascade posits that intestinal-type gastric adenocarcinoma develops along a defined pathway of pre-neoplastic stages. The cascade begins with chronic gastritis, most commonly caused by Helicobacter pylori (H. pylori) infection, and proceeds through GA, gastric intestinal metaplasia (GIM), both complete and incomplete, dysplasia, both low and high-grade, and culminating in intestinal-type gastric adenocarcinoma. Attempts in Europe have been made to identify patients at risk of developing GC and target them with surveillance oesophagogastroduodenoscopy (OGD). However, there remains uncertainty about GA's risk of developing into GC. This poses issues in terms of guiding the need for and determining intervals for surveillance OGDs, which are a costly form of surveillance. As such, we attempted to gather all available studies assessing the risk of GC developing from GA, which is the first step in the Correa cascade. This study was a comprehensive systematic review of published papers, reported per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. This systematic review, which included a substantial 25,455 patients across 18 studies, found that the relative risk (RR) of GC in those with GA, using standardised incidence ratios as a measure of RR, was 15.1, with a 95% confidence interval ranging from 13.5 to 16.9. We conclude that GA does increase the risk of developing GC, and this risk may be higher than previously appreciated. Further large-scale studies are needed in Western cohorts of patients to precisely define this risk and guide the need for surveillance programs. These future studies must be standardised to account for H. pylori status, the topographical distribution of the GA, and the methods for assessing the degree of GA.