Gastric cancer is the most common type of gastric tumor and is a malignant tumor of epithelial origin, i.e. gastric adenocarcinoma. Among the malignant tumors of the stomach, adenocarcinoma accounts for 95%, which is also the most common malignant tumor of the digestive tract and even ranks among the top of all malignant tumors in human beings. Early stage gastric cancer is mostly asymptomatic or has only mild symptoms. When the clinical symptoms are obvious, the disease is already in advanced stage. Therefore, we should be very alert to the early symptoms of gastric cancer to avoid delaying the diagnosis and treatment. Stomach cancer in China has the following characteristics: firstly, there are three major incidence factors: H. pylori infection; smoking; high salt intake. Secondly, there are three highs: high incidence rate, including male to female ratio of 3:1, age of onset 50-60 years; high metastasis rate of more than 50%; high mortality rate of more than 0.3/1000; and three lows: low early diagnosis rate of less than 10%; low radical resection rate of less than 50%; low 5-year survival rate of ≤50%.