A Japanese multicenter prospective cohort study is currently being conducted on endoscopic resection (ER) for early gastric cancer (EGC) using a Web registry system developed to determine short-term and long-term outcomes based on the absolute and expanded indications. All consecutive patients with EGC or suspected EGC undergoing ER at the 41 participating institutions from July 2010 to June 2012 are being enrolled in the study cohort using the Web registry system, and each patient will be followed up for a minimum of 5 years. The study investigation includes baseline patient and lesion characteristics as well as short-term and long-term outcomes. A survey program to collect information on long-term outcomes is also being introduced for patients subsequently followed up in institutions other than their original participating institutions, as well as patients for whom the original participating institutions have been losing track of their follow-up. The primary endpoint is 5-year overall survival, with en bloc resection, curative resection, complication, local recurrence, distant metastasis, metachronous EGC, and recurrence-free survival being secondary endpoints in addition to the successful collection of long-term outcome data on enrolled patients utilizing the survey program.