The etiology of esophageal cancer is not completely clear, but the following factors are related to the development of esophageal cancer: 1. Nitrosamines and fungi Nitrosamines are highly carcinogenic, which can make the epithelium of the esophagus undergo proliferative changes, gradually aggravate and finally develop into cancer. Some fungi can reduce nitrate to nitrite, promote the formation of secondary amines, so that the secondary amines are 50 to 100 times higher than before mold. A few fungi can also synthesize nitrosamines. 2. The susceptibility of genetic factors and genetic population is related to heredity and environmental conditions. Esophageal cancer has more significant family aggregation phenomenon, Henan Linxian esophageal cancer has positive family history accounting for 60%, and there is a significant increase in autosomal number and structural abnormality in families with high incidence of esophageal cancer. The occurrence of esophageal cancer may involve the activation of several oncogenes (such as C-myc, EGFr, etc.) and the inactivation of oncogenes (such as P53). 3.Malnutrition and lack of micronutrients in the high incidence areas of esophageal cancer in Asia and Africa found that most of the residents of the food lack of animal proteins and vitamins, vitamin B2 deficiency and epithelial hyperplasia related to vitamin C can block the role of nitrosamines. Trace elements in food, such as copper, manganese, iron, zinc content is low, which is also related to the occurrence of esophageal cancer. Dietary habits of esophageal cancer patients are related to eating rough food, eating too hot, too fast, because these factors cause damage to the epithelium of esophagus and increase susceptibility to carcinogens. The incidence rate of esophageal cancer in long-term drinkers and smokers is significantly higher than that in non-drinkers and non-smokers. 5.Other factors: chronic inflammation, mucosal injury and chronic stimulation of esophagus are also related to the development of esophageal cancer, such as corrosive injury of esophagus, chronic inflammation of esophagus, pancreatic achalasia and gastro-esophageal reflux caused by Barrett’s esophagus (esophageal mucosal columnar cell metaplasia), etc., which are all at the risk of cancerous transformation.