The causes of breast cancer are not yet fully understood, but some factors are related to the occurrence and progression of breast cancer, and preventive measures against these factors are currently being studied and explored. The prevention of breast cancer includes prevention of related factors, identification of high-risk groups (primary prevention), treatment and early detection of precancerous lesions (secondary prevention), and treatment of identified breast cancer (tertiary prevention). For the healthy population, primary and secondary prevention is mainly carried out. It can be done from the following aspects: 1. Change the bad lifestyle and maintain a healthy rhythm of life: Studies have concluded that there is a relationship between high fat diet and the occurrence of breast cancer, therefore, the intake of fatty foods such as fatty meat, cream, butter and egg yolk should be reduced, and less fried and deep-fried foods should be consumed. In addition excessive coffee and caffeine-containing beverages and avoid smoking. Usually should eat more green vegetables, fruits and other vitamin-rich foods. Work tension, mental stress and life rhythm disorder can cause endocrine disorder and decrease immunity, which is conducive to the growth of tumor, so work, life and entertainment should be arranged reasonably. Therefore, work, life and recreation should be arranged reasonably. Relaxing oneself frequently and participating in physical exercise and social activities can adjust the rhythm of life and reduce mental tension and psychological pressure. Avoid taking estrogen for a long time: Estrogen deficient people can show weakness, fatigue, irritability, excessive sweating, insomnia and other menopausal syndrome manifestations. Proper estrogen replacement therapy can relieve the above symptoms and make the patients energetic again. However, it should be properly applied under the guidance of a doctor and should not be taken without authorization, let alone in large quantities for a long time. Regular mammograms should be performed during the administration period. Close follow-up of high-risk group: The so-called high-risk group refers to the group with higher risk of breast cancer than the normal group, and this group should be closely followed up clinically for early detection of breast cancer. At present, the identified high-risk factors include being unmarried, having children, having a full-term birth >35 years old, not breastfeeding, early menarche (<12 years old), late amenorrhea, history of breast cancer in first-degree relatives, history of breast cancer on one side, cystic hyperplasia with moderate and severe epithelial atypia (especially cell anisotropy, long-term use of estrogenic drugs), etc. Active treatment of breast cancer-related diseases: Whether cystic hyperplasia of the breast is a precancerous lesion is still debated. Some data show that the risk of breast cancer is 2-3 times higher after the disease. Although fibroadenoma of the breast is a benign lesion, it can easily become malignant if it is treated for a long time. Therefore, the above diseases should be treated in time to avoid worries. V. Frequent breast self-examination: Women over 40 years of age should have frequent breast self-examination, generally once a month is better, but for patients with high-risk factors, the age of self-examination should be advanced. Once you find any abnormalities, you should go to the hospital and ask your doctor to rule out breast cancer. Breast cancer screening (physical examination and mammogram): We should pay attention to the screening of women's diseases. If there are high-risk factors, the screening age should be advanced.