The tertiary prevention of tumor is one of the main contents of malignant tumor diagnosis and treatment. A good tertiary prevention of malignant tumor can prevent 1/3 of cancers from occurring; make 1/3 of cancer patients achieve clinical cure or even complete cure through early detection, early diagnosis and early treatment; it can also reduce the pain of the remaining 1/3 of patients with advanced cancer, thus prolonging their survival. The content of tertiary prevention of tumor is as follows: 1. Primary prevention: i.e. etiological prevention, which can reduce the incidence of tumor in susceptible people by preventing or avoiding contact with the causative factors that can cause tumor development. It mainly includes controlling smoking, improving dietary habits, reducing environmental pollution, avoiding exposure to carcinogenic substances, preventing and controlling viral infections, etc. For example, patients who have been smoking for a long time can stop smoking by quitting. For example, long-term smokers can prevent the occurrence of lung cancer by quitting smoking. In addition, scientific diet, reasonable meal mix, less high-fat food and more fresh fruits and vegetables can reduce the incidence of cancers such as stomach, colon and pancreatic cancers. In addition, hepatitis B vaccination can also be used to prevent hepatitis B virus infection, thus reducing the incidence of liver cancer. 2. Secondary prevention: that is, to achieve early detection, early diagnosis and early treatment. Firstly, regular physical examination can detect diseases or potential risks of diseases at an early stage, which can lead to early intervention, such as physical examination, breast ultrasound, anal examination, fecal occult blood and exfoliative cytology examination. Secondly, to implement dynamic monitoring for tumor high-risk or susceptible people to discover possible early tumors and treat them as early as possible to improve the cure rate; 3. Tertiary prevention: that is, to provide active and effective treatment for patients already suffering from malignant tumors, which generally adopts a multidisciplinary and comprehensive treatment approach. Mainly through surgery, radiotherapy, chemotherapy, immunotherapy and other methods to prevent tumor recurrence and progression, reduce the disability and death rate of tumor, prolong the survival time of patients and improve their survival quality.