116 SUCCESSFUL ERADICATION OF HELICOBACTER PYLORI REDUCES THE DEVELOPMENT OF METACHRONOUS GASTRIC CANCER AFTER ENDOSCOPIC SUBMUCOSAL DISSECTION FOR EARLY GASTRIC CANCER: A PROPENSITY MATCHING ANALYSIS

Abstract

Helicobacter pylori infection is the most important risk factor for gastric cancer. Some randomized studies showed that successful H. pylori eradication after endoscopic resection of early gastric cancer (EGC) significantly reduced metachronous gastric cancer (MGC), whereas others showed that H. pylori eradication did not significantly contribute to reducing MGC. Our aim was to investigate the effect of H. pylori eradication on the development of MGC after endoscopic submucosal dissection (ESD) for EGC. Between October 2007 and October 2015, at our hospital, 701 consecutive patients with EGC underwent curative resection using the expanded indications for ESD according to the criteria in the Japanese Gastric Cancer Treatment Guidelines 2014. Of these patients, 378 who contracted H. pylori infection at the time of ESD were enrolled. Patients with familial adenomatous polyposis, those who had undergone surgical gastrectomy, or those whose follow-up duration was less than 1 year, were excluded. The patients included were divided into two groups as follows: those who failed or did not undergo H. pylori eradication (persistent group, n = 220), and those who successfully underwent H. pylori eradication (eradicated group, n = 128). We retrospectively compared the incidence of the development of MGC between the groups by using propensity score (PS) matching to reduce the effects of selection bias and potential confounding factors. The patients in the persistent group had significantly older age, lighter weight, and larger tumor size than the patients in the eradicated group (p < 0.01, p = 0.05, p = 0.01). After PS matching, 128 pairs of patients between the persistent and eradicated groups showed no significant difference in any covariate. The MGC developed in 22 patients (10.0%) in the persistent group and 5 patients (3.9%) in the eradicated group during the median follow-up period of 38.8 months (range, 12.4–114.0 months) and 40.5 months (range, 25.9–105.7 months), respectively. Before matching, the 5-year cumulative incidence rate of MGC was not significantly different between the persistent and eradicated groups (11.3% vs 3.8%, p = 0.06). After matching, the rate was significantly higher in the persistent group than the eradicated group (14.2% vs 3.8%, p = 0.01). In the Cox proportional hazard analysis, the eradicated group was not significantly associated with preventing MGC before matching (HR = 0.40, p = 0.07). However, the eradicated group was significantly associated with preventing MGC after matching (HR = 0.30, p = 0.02). Although this is a retrospective cohort study conducted at a single institution by using PS matching to adjust the background factors in the real world, it demonstrated that successful H. pylori eradication may reduce the development of MGC after ESD of EGC.