Use of antibiotics and probiotics reduces the risk of metachronous gastric cancer after endoscopic resection

Metachronous gastric cancer often occurs after endoscopic resection. Appropriate management, including chemoprevention, is required after the procedure. This study was performed to evaluate the association between medication use and the incidence of metachronous gastric cancer after endoscopic resection. This multicenter retrospective cohort study was conducted with data from nine hospital databases on patients who underwent endoscopic resection for gastric cancer between 2014 and 2019. The primary outcome was the incidence of metachronous gastric cancer. We evaluated the associations of metachronous gastric cancer occurrence with medication use and clinical factors. Hazard ratios were adjusted by age and Charlson comorbidity index scores, with and without consideration of sex, smoking status, and receipt of Helicobacter pylori eradication therapy during the study period. During a mean follow-up period of 2.55 years, 10.39% (140/1347) of all patients developed metachronous gastric cancer. The use of antibiotics other than those used for H. pylori eradication was associated with a lower incidence of metachronous gastric cancer than was non-use (adjusted hazard ratio (aHR) 0.56, 95% confidence interval (CI) 0.38–0.85, p = 0.006). Probiotic drug use was also associated with a lower incidence of metachronous gastric cancer com-pared with non-use (aHR 0.29, 95% CI 0.091–0.91, p = 0.034). In conclusion, the use of antibiotics and probiotic drugs was associated with a decreased risk of metachronous gastric cancer. These findings suggest that the gut microbiome is associated with metachronous gastric cancer development.