Primary prevention of tumors: etiological prevention It refers to preventive measures to eliminate or reduce cancer-causing factors in the general population to promote health and prevent cancer before it occurs. Effective as well as preventive measures include the following: 1. Smoking cessation: The causal relationship between smoking and lung cancer and other cancers has been established by several epidemiological studies worldwide, providing the best opportunity to date for human cancer prevention, and has been confirmed by practice in several developed countries. Smoking control can reduce approximately 80% or more of lung cancer and 30% of total cancer deaths. 2.Rational diet: The role of diet is universal, and research has focused on the intake of fat and vitamins within the diet. Eating a large amount of vegetables and fruits will reduce the occurrence of certain tumors. 3.Moderation of alcohol consumption: Alcohol consumption induces many tumors, mainly pharynx, oral cavity and esophagus, and has a synergistic effect with smoking. 4.Immunization: It has been clearly confirmed that human papilloma virus (HPV) is related to the occurrence of cancer of female cervix, and hepatitis B virus (HBV) increases the risk of primary liver cancer. 5.Prevention of occupational cancer: such as prevention of ionizing radiation and asbestos in the working environment. 6.Health education and health promotion: to tell the general public the known risk factors and protective factors of tumor through various forms and ways, so that they can establish reasonable dietary habits and healthy lifestyles, etc. Secondary prevention of tumor: pathogenetic prevention It refers to screening for precancerous lesions or early tumor cases in specific high-risk groups, so as to carry out early detection, early prevention and early treatment, and its measures include screening and intervention experiments. 1.Cervical cancer screening: Cervical smear has gained wide acceptance as the preferred method to reduce cervical cancer mortality. High-risk HPV testing is now being used in many countries for screening of high-risk populations. 2.Breast cancer screening: Breast smear under the condition of relatively high technology of smear can reduce the mortality rate of breast cancer; teaching breast self-examination to the public. Colorectal cancer screening: screening for early colorectal cancer by fecal occult blood (FOB); sigmoidoscopic screening can significantly reduce mortality. Screening of gastric cancer: Endoscopic screening of gastric cancer has been successful in Japan, and the detection rate of early gastric cancer is over 40%. 5.Esophageal cancer early diagnosis and treatment: The endoscopic iodine staining + indicative biopsy screening of esophageal cancer carried out in Lin County, China, has achieved good results. The esophageal epithelial severe atypical hyperplasia/carcinoma in situ detected by the examination can be treated with minimally invasive treatment such as endoscopic mucosal resection and argon ion coagulation therapy with good effect. Tertiary prevention of tumor refers to measures to prevent recurrence of existing tumor patients, reduce their complications, prevent disability, improve survival rate and recovery rate, and reduce pain caused by tumor, such as three-step pain relief, hospice care, etc.