Aspirin Use for Gastric Cancer Prevention in the Early Gastric Cancer Patients

Inclusion Criteria: * Men and women aged 19-70 years who underwent endoscopic resection for high-grade adenoma or early gastric cancer (category 4 \[non-invasive high grade neoplasm\] or category 5 \[invasive neoplasia\] according to the Vienna classification of gastrointestinal epithelial neoplasia \[Schlemper RJ, et al. Gut 2000;47:251-255.\]) * Final pathological results after endoscopic resection met the absolute or expanded criteria according to the Japanese Gastric Cancer Treatment guideline 2014 (version 4) * Patients who had negative H. pylori status or those who eradicated H. pylori status * Willingness to sign an informed consent form Exclusion Criteria: * Patients who received aspirin for the secondary prevention of cardiovascular diseases or cerebrovascular diseases * Regular aspirin uses (more than 3 times a week) with 2 months before screening visit * Patients who used anticoagulants or antiplatelet drugs for therapeutic purpose * Previous gastrectomy history * Current treatment for serious medical condition which could hinder participation (such as severe heart dysfunction, liver cirrhosis, renal failure, COPD or bronchial asthma, or uncontrolled infection) * High risk patients for bleeding complications (cerebral aneurysm, vascular malformation, esophageal or gastric varices, or hemophilia, etc) * Active peptic ulcer disease (patients who treated peptic ulcer completely could be enrolled) * Diagnosis and active treatment for other organ cancer (except carcinoma in situ, and non-melanoma skin cancer) within 5 years * Non-curative resection of early gastric cancer after endoscopic resection * Aspirin allergy or contraindication of aspirin use * Pregnant or lactating women * Alcoholism, drug abuse * Inadequate patients for study enrollment according to the evaluation of the study physician * Inability to provide an informed consent * Patients who took a 28-day run-in-period medication less than 80%