A Phase III trial of inhibitory effect of metachronous gastric cancer by Helicobacter pylori eradication for patients after endoscopic submucosal dissection

INTERVENTION: Patients in eradication group undergo eradication of Helicobacter pylori within 6 months after ESD. Patients in non‐eradication group are followed up without eradication of Helicobacter pylori. CONDITION: Early gastric cancer PRIMARY OUTCOME: The proportion of 5 ‐year cumulative metachronous gastric cancer SECONDARY OUTCOME: The proportion of 5 ‐year cumulative metachronous gastric cancer according to pepsinogen levels; The proportion of annual cumulative metachronous gastric cancer; Overall survival time; Disease free survival time; The proportion of the incidence of reflux esophagitis; The proportion of exacerbation of reflux esophagitis INCLUSION CRITERIA: 1) ESD specimen revealed tubular adenocarcinoma histologically and primary cancer 2) curative resection(absolute and expanded criteria) 3) both single and multiple lesions 4) lesions expected not to occur stricture due to ESD scar 5) Helicobacter pylori positive 6) no history of eradication of Helicobacter pylori 7) clinical N0 and M0 8) an age of 60 to 81 years 9) an Eastern Cooperative Oncology Group(ECOG) performance status(PS) of 0 or 1 10) no history of gastrectomy and esophagectomy 11) no prior chemotherapy within 5 years (in case of breast cancer, within 10 years) 12) laboratory data of total bilirubin is less than 2.5mg/dL, serum creatinine less than 2.0mg/dL 13) written informed consent