The epidemiological survey results of tumors in large cities in China from 1993 to 1997 showed that the incidence of gastrointestinal tumors accounted for more than half of the total malignant tumor incidence, among which stomach cancer, colorectal cancer and esophageal cancer ranked 1st, 4th and 6th respectively, accounting for almost half of all tumor incidences. Gastrointestinal cancer, colorectal cancer and esophageal cancer are the 1st, 4th and 6th tumor incidence respectively, accounting for almost half of all tumor incidence and mortality. In 2005, there were 185,211 new cases of esophageal cancer in China, accounting for about 50% of the new cases in the world. It is conservatively estimated that the annual cost of esophageal cancer diagnosis and treatment in China is 5-7 billion RMB, and once clinically diagnosed, it is often in the middle to late stage, with a 5-year survival rate of less than 20%. In contrast, the 5-year survival rate of early esophageal cancer is over 90% after treatment. Gastrointestinal endoscopy is an important method to diagnose early esophageal cancer, and it is very important to conduct endoscopy work in high incidence areas and high-risk groups to strengthen the early diagnosis rate of esophageal cancer and carry out early intervention, which is very important to improve the 5-year productivity and even cure rate of esophageal cancer. Up to now, only Prof. Wang Guoqing has conducted endoscopic screening work in high incidence sites of esophageal cancer in China many years ago, and it is far from popular nationwide, leading China to the embarrassing situation of high incidence rate and low early diagnosis and early treatment rate compared with western countries and Japan, etc. And, the gap is getting bigger and bigger. Gastric cancer is one of the most common malignant tumors, accounting for the first place of incidence and mortality of malignant tumors in China. It is estimated that in 2000, there were 331,000 new cases and 245,000 deaths of gastric cancer in China, and by 2010, the numbers will reach 436,000 and 323,000; gastric cancer not only poses a serious health threat, but also brings huge social and economic losses, and the annual cost of treatment spent on gastric cancer is about 15 billion. According to the depth of lesion infiltration, it can be divided into early-stage gastric cancer and progressive gastric cancer. In China, early-stage gastric cancer accounts for only 2%-10% of patients who visit the clinic, with a 5-year survival rate of 95-97%, while about 85% of patients with progressive gastric cancer can be operated, with a 5-year survival rate of 20%-30%. Therefore, endoscopic screening of gastric cancer in the population with high incidence of gastric cancer, improving the diagnosis rate of early gastric cancer and performing endoscopic (minimally invasive) treatment of early gastric cancer can help improve the cure rate and 5-year survival rate of gastric cancer. In China, colorectal cancer is one of the common malignant tumors with high incidence rate and most of them are in the middle and late stages. With the development of China’s economy and the continuous improvement of people’s living standard, the incidence of colorectal cancer has been increasing year by year, from the 6th place of malignant tumors 10 years ago to the 4th place at present. Although the diagnosis and surgical treatment of colon cancer have made great progress, its 5-year survival rate has hovered around 50% in the past 10 years. The total national disease burden of colon cancer will reach $40 billion. Therefore, improving the detection rate of precancerous colon lesions (colon adenomas) and early endoscopic resection, and enhancing endoscopic surveillance of colon cancer in high-risk groups can help reduce the incidence of colon cancer. The early diagnosis of colon adenoma and colon cancer mainly relies on gastrointestinal endoscopy, which can both observe under direct vision and take biopsy. Endoscopy can comprehensively and reliably perform luminal examination of the whole colon, which can not only detect larger lesions, but also do qualitative biopsy of smaller lesions as well as electrodesiccation treatment, so that multiple primary cancers existing at the same time are not easily missed. The prognosis of advanced gastrointestinal tumors is poor and the treatment effect is unsatisfactory. Prevention as well as early diagnosis and early treatment can significantly improve the prognosis. Primary prevention of digestive tumors often requires a long period of intervention to be effective, and it is difficult to achieve a breakthrough in the near future. Therefore, it is very important to conduct early diagnosis research for the high incidence population and high incidence area of digestive tumors to reduce the incidence of cancer; to improve the early diagnosis rate of cancer and to carry out early intervention to improve the 5-year survival rate. This is in line with the strategic shift of national cancer treatment policy from emphasizing pure treatment to emphasizing early detection and early intervention and shifting the focus of treatment forward. With the continuous progress of endoscopic diagnosis technology of early GI cancer, the detection rate of early GI cancer has increased significantly. Although surgery can completely remove the lesion, it has the disadvantages of large trauma, slow recovery and high complication rate, while endoscopic treatment is less traumatic, which can ensure complete resection of tumor while preserving normal tissues and their functions to the maximum extent, with low complication rate and significantly improving patients’ postoperative quality of life. The choice of endoscopic treatment for early cancer of digestive tract has been accepted by more and more doctors. Endoscopic mucosal resection (EMR) for early-stage tumors has been gradually developed with the continuous advancement of endoscopic treatment technology. Generally speaking, early stage tumors without lymph node metastasis and shallow infiltration depth can be indications for EMR. However, the specific indications criteria in the process of practical clinical application are still controversial. Moreover, the anatomical structures of esophagus and gastrointestinal tract have their own characteristics, so their respective indications are also different. EMR is difficult to excise large superficial lesions, and it is easy to remove lesions in stages, and the excised specimens are greatly damaged by electrocoagulation, which makes histological evaluation difficult. In the late 1990s, the endoscopic submucosal dissection (ESD) technique was first developed in Japan, in which the mucosa of the gastrointestinal tract lesion is peeled off in one piece from the submucosa by the action of high-frequency electricity through the endoscope and the selection of a suitable electric knife. It is a milestone in the development of endoscopic technology as it can completely remove large superficial lesions at one time. Endoscopic diagnosis and treatment of early GI cancer in China have made great progress in recent years, but there are still some problems: (1) the endoscopic treatment rate of early GI cancer in China is still low, and many patients have undergone unnecessary surgical procedures; (2) in the past, scholars from East and West had great differences in pathological diagnosis criteria of early GI cancer, but in 2000, scholars from East and West reached a considerable consensus on the Vienna classification. In 2002, endoscopists, surgeons and pathologists from Japan, Europe and the United States discussed in detail the Japanese “superficial neoplasia of the gastrointestinal tract” in Paris, and the understanding of the East and West gradually came closer, especially on the embedding, sectioning and pathological diagnosis of endoscopic resected specimens. (3) ESD technology is still in the process of improvement and maturation, and it has just started in China, so it is necessary to further summarize the experience and conduct a multicenter prospective follow-up study to make a comprehensive evaluation of ESD technology.