Tumors are new organisms formed by the proliferation and abnormal differentiation of normal cells in the body under the long-term action of different initiating and promoting factors. Tumors can be divided into benign, malignant, and junctional tumors according to their benign or malignant nature. Among them, malignant tumors can be divided into epithelial tumors and mesenchymal tumors according to their tissue origin. Cancer includes what we usually call cancer, such as lung cancer, breast cancer, liver cancer, stomach cancer and so on. When we talk about tumor, most people first think of advanced stage and death, and it can be said that “talking about tumor is scary”! In fact, tumors are not that scary. Tumors are caused by the long-term interaction of various factors such as environment, diet, heredity, viral infection, and lifestyle choices. These initiating and promoting factors can be changed through active efforts. Among the tumor diseases, 1/3 of them can be prevented, such as cervical cancer, breast cancer and prostate cancer, and early screening is of great significance in these diseases; 1/3 of them can be treated, such as lymphoma and leukemia, which can be cured through high-dose chemotherapy and bone marrow supportive therapy; and 1/3 of the tumors can be relieved of pain, improve the quality of life, and prolong the life through the best supportive therapy, such as liver cancer. For example, liver cancer. Based on these three 1/3, the International Union Against Cancer (IUAC) has put forward the concept of three-level prevention of malignant tumors: primary prevention is to eliminate or reduce the factors that may cause cancer to prevent the occurrence of cancer; secondary prevention is to reduce the mortality rate of cancer, early detection, early diagnosis and early treatment; tertiary prevention is to treat the symptoms, improve the quality of life and reduce pain to prolong life. Primary prevention 1.Improve living habits – quit smoking, do not abuse alcohol; 2.Good dietary habits – consume fresh fruits and vegetables, avoid high salt, moldy food; 3.Attention to occupational protection – reduce contact with asbestos, benzene and other carcinogens. Secondary prevention: Early detection, early diagnosis and early treatment; 2. Regular screening of high-risk groups; 3. Timely treatment and follow-up of precancerous lesions (chronic atrophic gastritis, cervical erosion, colon polyps, long-lasting lower limb ulcers, etc.); 4. Chemoprevention and immunoprevention and other new means. Tertiary prevention is mainly to improve the quality of life and prolong life, including all kinds of palliative care and symptomatic treatment, in which the three-step pain treatment for cancer is especially important, and its basic principles are: ① pain relief according to the order of non-morphine → morphine → morphine → strong morphine → pain relief other than medication; ② start from a small dose, and gradually increase the amount depending on the effect of pain relief; ③ give the medication according to the order of oral medication → rectal medication → injectable medication; ④ give the medication on a regular basis. (iv) Regular administration of the drug. There is no need for us to be so afraid of tumors, we should treat tumors correctly, improve our living habits through the tertiary prevention of tumors, stay away from carcinogens, and stay away from tumors as far as possible; if you are unfortunate enough to suffer from tumors, you should be brave to face them and set up confidence for yourself to overcome the disease. We hope that everyone who sees and understands this knowledge will stay away from tumors and have good health.