I. How to prevent breast cancer? 1.Changing bad lifestyle Bad lifestyle is undoubtedly an important reason for the occurrence of breast cancer. Therefore, relieving mental tension, not staying up late, not smoking, avoiding abortion, establishing good eating habits and conforming to the natural reproduction and reproduction rules of human beings are all things that we can do by ourselves. Changing the bad habits will reduce the harm of breast cancer to our health. 2.Get a good screening of breast diseases The chance of a girl suffering from breast cancer is 10% since she was born, so screening is the best way to prevent it. Ultrasound and surgical examination should be performed in every screening, and mammography should be considered for women over 35 years old. 3. Preventive treatment For benign breast disease, short-term preventive application of triamcinolone can be used. 4. Avoid hormone replacement therapy The use of hormone replacement therapy leads to a higher risk of breast cancer, and the risk of breast cancer increases to 35% after 5 years of use. The risk of developing breast cancer increases to 35% after 5 years of use. After 5 years of discontinuing hormone replacement therapy, the risk of developing breast cancer returns to normal. Hormone replacement therapy that uses both estrogen and progestin may have a higher incidence of breast cancer than estrogen-only hormone replacement therapy. It is estimated that prophylactic bilateral mastectomy can reduce the risk of breast cancer in BRCA mutation carriers by 85% to 90%. BPM may be a radical but effective treatment for patients with BRCA1/2 mutation carriers in whom all breast epithelium is likely to be abnormally hyperplastic. Prophylactic mastectomy may extend life expectancy by 3 to 5 years if performed in patients aged 30 years, but BPM is not relevant in patients > 60 years.