With the introduction of optical fiber endoscopy in the 1970s and the application of electronic endoscopy 10 years later, the development from image diagnosis to direct observation of physical images such as specific shape, size, contour and color of lesions under endoscopy, as well as the ability to simultaneously bite into tissues for qualitative pathological diagnosis; the application of magnifying endoscopy and ultrasound endoscopy, which has both endoscopic and ultrasound examination as one, has further expanded the functions of endoscopy and made In particular, the pigmented endoscopic techniques developed in the 1990s, the most applied of which is the comprehensive technique of endoscopic iodine staining of esophageal mucosa and indicative biopsy, can clearly reveal precancerous foci and early cancer foci that only have color changes or microscopic morphological changes on the mucosal surface but are not clear to the naked eye after iodine staining, which is a breakthrough in endoscopic early diagnosis technology. This is a breakthrough and a qualitative improvement of endoscopic early diagnosis technology, which can raise the diagnosis to a new level and lay the foundation for early diagnosis and treatment of precancerous lesions and early cancer of esophagus. Endoscopy has its own unique features for the diagnosis of early cardia cancer. Due to the characteristics of the anatomical structure and function of the cardia, the small curved side of the cardia is a high incidence of cardia cancer, which is tightly bolted to the posterior abdominal wall by the short and thick left gastric artery and its branches and the gastric anchor formed by the posterior peritoneum. The bend side is weak, and the mucosal layer is only 3 mm thick, and this is the part that receives the greatest mechanical impact from the food mass. According to the 420 cases reported by Prof. Wang Guoqing and 231 cases of early pancreatic cancer in the Fourth Hospital of Hebei Medical University, 75% of them occurred in the posterior wall of the small curved side of the cardia; combined with the endoscopic signs of early pancreatic cancer such as erosion, congestion, bleeding, roughness, etc., it is an important step to detect and diagnose early pancreatic cancer by targeting this area for detailed and precise endoscopic investigation. Moreover, it is a one-two punch to complete the examination of two major cancers, esophageal cancer and cardia cancer, in one endoscopic examination. Regarding the principle of endoscopic iodine staining technique for early diagnosis, as early as 1964, Wenzhen Li and Guodong Gao from Hebei Medical University conducted iodine staining study on esophageal surgical specimens and found that the change of glycogen consumption of esophageal mucosal squamous epithelial cells in the process of carcinogenesis was closely related to the degree of mucosal coloration, and after the glycogen consumption was exhausted after carcinogenesis, the mucosa was not colored, while the normal mucosa was brownish black, and pointed out that iodine staining technique It was pointed out that iodine staining technique could help to improve the early diagnosis rate of esophageal cancer. However, it did not attract much attention. In the 1980s, Guo Guoqing used this technique on 3350 people aged 40-65 years old in a site with a high incidence of esophageal cancer in China, and screened out 8%-10%, 3%-5% and 4%-5% of moderate and severe atypical hyperplasia and cancer respectively (early cancer accounted for 2/3), which attracted the attention of domestic scholars. Guo Xiaoqing performed routine iodine staining and pathological examination on 336 patients with no swallowing symptoms but with rough or discolored esophageal mucosa, and detected 104 cases (28.5%) of moderate atypical hyperplasia, 61 cases of moderate and severe atypical hyperplasia, 20 cases of carcinoma in situ, and 23 cases of mucosal carcinoma, which illustrates the practical value of iodine staining technique for esophageal mucosa and the prospect of its application. However, endoscopy is costly and painful, and there is a lack of uniform design and large sample and multicenter clinical control studies, which needs to be further standardized to achieve greater benefits. It is worth mentioning that long before the introduction of endoscopy, the esophageal laparoscopy developed by Qiong Shen in the 1950s, 278,208 people were examined at high incidence sites between 1961 and 1990, and a total of 3,693 cases of esophageal and cardia cancer were screened, with a cancer detection rate of 1.33%, of which 1,999 cases (40.59%) were early stage cancers. Of these, 204 cases of early cancer were treated by Shao Lingfang, and the 5-year and 10-year survival rates after surgery were as high as 92.6% and 71.6%, respectively. Today, the review of the esophageal pull-down cytology method has some shortcomings such as high false-positive rate, which affects the continued promotion of its application. However, it has created an effective method for human to detect early esophageal and cardia cancers more than 50 years ago, providing a technical platform for understanding and studying early cancers, greatly promoting the prevention and treatment process of esophageal and cardia cancers in China, which is of great value and has made a definite historical contribution. The method of swallowing hollow metal balls to collect trace gastric fluid for detection of occult blood, pH, IgA and IgG adopted by the Fourth Hospital of Hebei Medical University in the 1980s and the method of swallowing occult blood beads to detect occult blood in gastric fluid adopted by Qin Dexing and Wang Guoqing in the 1990s were used as the primary screening means for the population in high incidence sites. The method is simple, safe, and the compliance of the test subjects is good, and certain results were received. However, both methods were discontinued because of the drawbacks of high false positive rate and positive reaction even at 1/10 000 blood dilution. However, their original idea of using a test method with microscopic body fluids as a means of primary screening in the population deserves attention. There is a need to further explore and develop a simple primary screening method that can effectively concentrate the primary screening population and reduce the number of endoscopic final screens, which is an important issue to be addressed in current population screening. In the late 1980s, research on esophageal and gastric cancers entered the molecular level, and it is believed that carcinogenesis is triggered by the accumulation of oncogenes and oncogenes alterations in cells, and through events involved in cell cycle regulation, signal transduction, cell differentiation and apoptosis, which interfere with the normal differentiation and proliferation of cells. Through more than 20 years of research, Lu Shixin concluded that the occurrence and development of esophageal cancer are associated with the activation of oncogenes such as C-myc, EGFr, int-2, Cyclin D and the deletion and mutation of oncogenes Rb, p53, MCC, APC, MTSI. As many as dozens of related genes and molecular markers have been reported now. However, due to the clustered regulation pattern and complex action network among genes, markers with high sensitivity and specificity that can be used as molecular early warning and molecular diagnosis have not been found yet and need to be further explored.