Risk of Gastric Cancer Among Patients With Intestinal Metaplasia of the Stomach in a US Integrated Health Care System

BACKGROUND & AIMS: Gastric intestinal metaplasia (GIM) is a common finding from routine endoscopies. Although GIM is an early step in gastric carcinogenesis, there is controversy regarding routine surveillance of patients with GIM in regions with a low prevalence of gastric cancer. We aimed to determine the incidence of gastric cancer among patients with GIM and risk factors for gastric cancer. METHODS: We performed a retrospective cohort study of patients from the Kaiser Permanente Southern California region diagnosed with GIM from 2000 through 2011. GIM was identified by a keyword search of pathology reports; gastric cancer cases were identified by cross-reference with an internal cancer registry. The incidence of gastric cancer in patients with GIM (n = 923; median age at diagnosis, 68 y) was compared with that of an age-and sex-matched reference population (controls). Risk factors such as ethnicity, smoking status, history of Helicobacter pylori infection, and family history of gastric cancer were evaluated by individual Cox proportional hazards regression. We then performed a second case-cohort study to evaluate the risk of gastric cancer based on the location and extent of GIM. The median duration of follow-up evaluation was 4.6 years (interquartile range, 3.0-6.7 y). RESULTS: We identified 25 patients with GIM who developed gastric cancers. Seventeen cases of cancer were diagnosed at the same time as the diagnosis of GIM. Eight cases of cancer were identified within a median time period of 4.6 years after a diagnosis of GIM (interquartile range, 2-5.7 y). The overall incidence rate for the cohort was 1.72 (95% confidence interval, 0.74-3.39). Among the risk factors evaluated, only family history (hazard ratio, 3.8; 95% confidence interval, 1.5-9.7; P = .012) and extent of GIM (odds ratio, 9.4; 95% confidence interval, 1.8-50.4) increased the risk for gastric cancer. The incidence rate for gastric cancer in patients with a positive family history was 8.12 (95% confidence interval, 1.67-23.73). CONCLUSIONS: In an analysis of patients with GIM listed in the Kaiser Permanente Southern California database, 2.7% were diagnosed with gastric cancer; almost 70% of cases of gastric cancer were detected at the time of GIM diagnosis. Family history and extensive metaplasia were associated with an increased risk of subsequent gastric cancer. Targeted surveillance of patients with these criteria could increase early detection of gastric cancer.