Obstructive sensation or dull pain behind the sternum when swallowing dry food is one of the early and middle stage manifestations of esophageal cancer. The main symptom is progressive dysphagia. In the early stage, there may be only discomfort or blockage when swallowing, pain behind the sternum or discomfort behind the sternum when swallowing food. Causes of obstruction or dull pain behind the sternum when swallowing dry food: 1. Dietary habits Long-term consumption of rough, hard and overheated food, or excessive intake of stimulating items such as chili, garlic, vinegar, tobacco and alcohol. The incidence of alcohol consumption is more than 50 times higher than that of non-drinkers, and the incidence of smoking and drinking is 156 times higher than that of non-smokers and non-drinkers. 2, nitrosamines and precursor substances The favorite foods of residents in the high incidence area, such as sauerkraut, bean paste, dried potatoes, dried radish, corn flour, etc., contain more nitrosamines and precursor substances, the latter can be reduced to nitrosamines by the action of gastric acid in the stomach. 3.Nutritional factors and trace elements The lack of protein, vitamins and essential fatty acids in the diet of esophageal cancer-prone areas can lead to proliferation and interstitial changes of esophageal mucosa and further carcinogenesis. The content of many trace elements such as molybdenum, copper, cobalt, iron and zinc in the soil and water source in the area with high incidence of esophageal cancer is reduced, especially the lack of molybdenum increases nitrate in the soil, which facilitates the synthesis of nitrosamines. 4.Genetic factors and oncogenes Esophageal cancer has a significant phenomenon of family cohesion. According to the statistics of high incidence area of esophageal cancer, it can reach about 27%-61%.