With the increasing understanding of cancer, it is gradually realized that cancer prevention is the most effective way to fight against cancer. Many studies have shown that cancer can be avoided, 1/3 of cancers can be prevented, and 1/3 of cancers can be cured if they are diagnosed early. Reasonable and effective palliative care can improve the quality of survival of the remaining 1/3 of cancer patients. Today’s technological advances present many challenges to our traditional habits, and new perspectives on health require constant awareness. Improving lifestyles and optimizing the surrounding environment to promote health. Tumor prevention and control can play a preventive role only if it is included in people’s daily life and work agenda. The ultimate goal of cancer prevention is to reduce the incidence and mortality of cancer. I. How to prevent the occurrence of cancer Preventing the occurrence of cancer is the first level of prevention or etiological prevention. The task includes studying the causes and risk factors of various cancers and taking preventive measures against specific cancer-causing factors such as chemical, physical and biological factors: 1. Smoking mainly causes cancer in lung, pharynx, larynx and esophagus, but also increases the risk of tumors in many other areas. 2.Improve dietary structure–A survey by the American Diet, Nutrition and Cancer Council (DNC) shows that colon, breast, esophageal, stomach and lung cancers are most likely to be prevented by changing dietary habits. In fact, a proper diet may have a preventive effect on most cancers, especially plant-based foods have a variety of cancer-preventing ingredients, which are effective in preventing almost all cancers. 3.Avoid the influence of environment, infection, drugs and other factors – Pressing some chemical substances due to occupation and environment can lead to tumors in different parts of the body. For example, lung cancer (asbestos), bladder department (aniline dyes), leukemia (benzene). Some infectious diseases are also very closely linked to certain cancers: for example, hepatitis B virus and liver cancer, human papilloma virus and cervical cancer. Exposure to some ionizing rays and large amounts of ultraviolet light can also cause certain tumors, especially skin cancer. Commonly used drugs with carcinogenic properties include sex hormones – estrogens and androgens, and the anti-estrogen drug triamcinolone. Estrogens widely used in postmenopausal women are associated with endometrial cancer and breast cancer. If cancer can be diagnosed early, it can be cured, i.e. secondary prevention or preclinical prevention, the goal of which is to prevent the development of the initial disease. The task includes “three early” (early detection, early diagnosis and early treatment) measures for cancer symptoms. It aims to stop or slow down the development of the disease, reverse it to stage 0 as early as possible, and restore health. 1. Pay attention to the 12 danger signs of cancer: (1) Gradual increase in the size of palpable lumps on the body surface or superficially. (2) Long-term fever of unknown origin. (3) Sternal discomfort or even choking sensation when swallowing food. (4) Persistent cough with blood in the sputum. (5) Tinnitus, hearing loss, epistaxis, blood in nasopharyngeal secretions. (6) Irregular vaginal bleeding outside the menstrual period or after menopause, especially contact bleeding. (7) Breast lumps with poor mobility and adhesion to the skin; “orange peel” changes on the surface of the breast; enlarged lymph nodes in the axilla on the same side of the breast with lumps. (8) Persistent digestive abnormalities, change in stool and urine habits, occult blood in stool, blood in stool, hematuria. (9) Long-term ulcers that do not heal. (10) Short-term enlargement of moles and warts, deepening of color, hair loss, itching, and rupture. (11) Unexplained weight loss. (12) If there is a painless lump in the long bone area. 2.Universal examination for certain population i.e. health checkup, such as cervical cytology screening or HPV test, chest fluoroscopy, etc. 3.Treatment of precancerous lesions: such as atypical hyperplasia and chemosis of esophageal mucosa epithelium, gastric mucosa and atrophic gastritis, chronic hepatitis and cirrhosis, colon polyps, hyperplasia and chemosis of bronchial epithelium, etc. 4.Strengthen the monitoring of susceptible people: people with genetic susceptibility to cancer and family history of cancer are the susceptible people of cancer. They must be monitored regularly. 3. To actively treat cancer in the face of cancer Reasonable and effective palliative care for cancer, i.e. tertiary prevention, is also called clinical (stage) prevention or rehabilitative prevention. Its goal is to prevent the deterioration of the disease and prevent disability. Its task is to adopt a multidisciplinary comprehensive diagnosis, and the treatment methods are different for different tumor sites, types, grades and gender. The correct choice of reasonable or even the best treatment plan is to extinguish cancer as early as possible, try to restore function, promote recovery, improve quality of life and even return to society. Although biochemical, immunological and imaging diagnoses of tumors have been developed, pathological diagnosis is still the main way to determine the nature of tumors. Pathological examination is one of the most reliable methods to diagnose tumor. It is to make a smear from the secretion of diseased organ or to directly take a small piece of tissue from the lesion to make a section and place it under the microscope to observe the cell morphology and structure to determine the nature of the tumor. Pathology is usually divided into two major parts: histopathology and cytopathology. Pathological diagnosis can not only determine the benignity and malignancy of tumor and its prognosis, but also provide a reliable basis for treatment. However, pathological diagnosis also has limitations. Because the biopsy specimen, macroscopic sampling and sectioning are all sample examinations, what is finally seen under the light microscope is only a very small part of the lesion and sometimes cannot represent the whole lesion. In addition, the reliability of pathological diagnosis is also related to the selection of pathological specimens. Sometimes there are also false negative results. If the clinical diagnosis is not consistent with the pathological diagnosis, the pathological diagnosis should be reviewed in a timely manner, and if the pathological diagnosis is correct, the selection of the pathological specimen can be considered to be comparable. If necessary, re-take the material and do pathological diagnosis again. In order to avoid misdiagnosis and delay in treatment.