The Incidence of Gastric Adenocarcinoma Among Patients With Gastric Intestinal Metaplasia A Long-term Cohort Study

Background and Aims: Gastric intestinal metaplasia (IM) has been known as a premalignant condition, but estimates of its cancer risk vary widely. We aimed to analyze cancer risk of gastric IM by a long-term cohort study. Methods: We conducted a hospital-based study that included all patients with gastric IM between 1992 and 2010, and the development of gastric adenocarcinoma was evaluated until July 2011. Patients developing gastric cancer <= 180 days after the index diagnosis of IM were excluded. The incidence rate, the cumulative incidence, and the standardized incidence ratio (SIR) of gastric cancer were determined, and hazard ratios (HRs) of risk factors were calculated. Results: We identified 7059 patients with a median follow-up duration of 5.1 years, and 81 patients developed gastric adenocarcinoma during the study period. The 5-, 10-, and 15-year cumulative incidences of gastric cancer were 0.9% [95% confidence interval (CI), 0.6-1.1), 2.0% (95% CI, 1.5-2.6), and 3.0% (95% CI, 2.0-4.0), respectively. On multivariate analysis, older age (eg, 75 y and above; HR=7.4; 95% CI, 2.8-19.6), low-grade dysplasia (HR=4.0; 95% CI, 2.1-7.9), and high-grade dysplasia (HR=18.8; 95% CI, 9.0-39.5) were independent risk factors. As compared with the risk in the general population, the SIR of gastric cancer among patients with gastric IM was 2.5 (95% CI, 2.0-3.1). However, the SIR was only 2.0 (95% CI, 1.5-2.6) in the nondysplasia subgroup, but was up to 35.2 (95% CI, 15.2-69.4) in the high-grade dysplasia subgroup. Conclusions: Gastric IM is an important risk factor for gastric cancer, but surveillance should be arranged only for those at an especially high risk.