Precision risk stratification of primary gastric cancer after eradication of H. pylori by a DNA methylation marker: a multicentre prospective study.

Background: Precision cancer risk stratification for gastric cancer is urgently needed for the growing number of healthy people after Helicobacter pylori eradication. The epimutation burden in non-malignant tissues has been associated with cancer risk in multiple cross-sectional studies.

Objective: To confirm the clinical usefulness of a DNA methylation marker for epimutation burden, and to identify a cut-off methylation level for a super-high-risk population.

Methods: Healthy people after H. pylori eradication with open-type atrophy were prospectively recruited. DNA methylation levels of a marker gene, RIMS1, were measured in biopsy specimens from gastric antrum and body. The primary endpoint was the incidence rate of gastric cancer in quartiles of the methylation levels.

Results: 1624 participants had at least one endoscopic follow-up with a median follow-up of 4.05 years, and a primary gastric cancer developed in 27 participants. The highest quartile of RIMS1 methylation levels had a higher incidence rate (972.8 per 100 000 person-years) than the lowest quartile (127.1). Cox regression analysis revealed a univariate HR of 7.7 (95% CI 1.8-33.7) and an age- and sex-adjusted HR of 5.7 (95% CI 1.3-25.5). As a secondary objective, a cut-off methylation level of 25.7% (95% CI 1.7-7.7) was obtained to identify a population with a super-high risk based on the number needed to screen of 1000.

Conclusions: A DNA methylation marker can risk-stratify healthy people after H. pylori eradication even though all of them have clinically high risk. Individuals with super-high risk will need more frequent gastric cancer screening than currently recommended. Background: UMIN-CTR000016894.