Because advanced gastric cancer shows poor prognosis, it is important to detect early gastric cancer or precancerous gastric adenoma patients who have a cure rate of 95% or more. Moreover, a large part of early gastric cancer can be completely resected by endoscopic resection, thus ensuring a very high quality of life for patients. However, there are currently no markers that can be used for diagnosis of early gastric cancer or gastric adenoma. In addition, the biggest problem after endoscopic resection of early gastric cancer is metachronous recurrence of the cancer, which requires repeated endoscopic resection or additional surgical gastrectomy. However, there are no discovered markers for prediction of recurrence. Liquid biopsy is a method of obtaining body fluids such as gastric juice or effusion through an endoscopic inlet during gastroscopy or colonoscopy and blood. Based on the advanced analysis method, liquid biopsy reveals more genetic information than tissue biopsy. Therefore, it is highly likely to become an essential factor in future personalized medicine. Therefore, this study was designed to identify whether tumor's molercular profiling based on tissue or blood could be used for prediction of prognosis and diagnosis of early gastric cancer and precancerous gastric adenoma.