Esophageal cancer is one of the common malignant tumors in humans. About 300,000 people die from esophageal cancer worldwide every year. The incidence of esophageal cancer in China has obvious characteristics of regional distribution, such as the distribution of irregular concentric circles in north China Taihang Mountains and northwestern Sichuan Basin, with the highest incidence in the center of the circle and decreasing in all directions. In coastal areas, the incidence rate gradually decreases from northeast to southwest, and the incidence rate of esophageal cancer can vary by tens of times with regional changes and distance. Esophagus is the tube connecting stomach and pharynx, which is about 25-30 cm long. Cancer occurring in esophagus is called esophageal cancer, which is one of the most common malignant tumors. Its occurrence is often related to diet, smoking, alcohol abuse, chronic inflammation of esophagus and genetics, etc. The incidence increases with age from 30 years old and peaks from 50 to 69 years old. There are more men than women. Esophageal cancer can occur in upper, middle and lower esophagus: middle segment is the most common (57.2%), lower segment is the second (29.6%) and upper segment is less common (13.1%). The incidence ratio of esophageal cancer to cardia cancer is about 4 to 5:1. The mortality rate of esophageal cancer in China is higher in men than in women. The ratio of male to female in the high incidence area is close, and the age of death is about 10 years earlier than that in the low incidence area, which indicates that there are strong carcinogenic factors in the high incidence area. The age of incidence is higher in the high age group and gradually decreases after 70 years old. The average age of death in China is 63 and 49 years for men and women combined, and the proportion of each age group is different, with the highest proportion between 55 and 74 years old. This shows that esophageal cancer is a common disease among middle-aged and elderly people. The development of esophageal cancer generally passes through the stages of epithelial atypical hyperplasia, carcinoma in situ and invasive carcinoma. Esophageal squamous epithelial atypical hyperplasia is an important precancerous lesion of esophageal cancer, and it usually takes several years or even a dozen years from atypical hyperplasia to cancer. It refers to the malignant lesion formed by the abnormal proliferation of esophageal squamous epithelium or glandular epithelium. Because of this, some esophageal cancers can be detected early and can be completely cured. For patients with dysphagia or foreign body sensation, gastroscopy should be performed as early as possible to detect early esophageal cancer or precancerous lesions.