I. Causes of breast cancer Estrogen is directly related to the development of breast cancer. Early age of menarche, late age of menopause, infertility and age of first full-term delivery are related to the development of breast cancer. The risk of developing breast cancer is 2-3 times higher in first-degree relatives than in the general population. The relative risk of breast cancer is higher in those with highly hyperplastic or atypical hyperplasia of breast lobular epithelium. Overnutrition, obesity and high-fat diet may enhance or prolong the stimulation of estrogen on breast epithelial cells and increase the chance of development. In addition, environmental factors and lifestyle also have a certain relationship with the development of breast cancer. Breast cancer is a systemic disease, therefore, it advocates the principle of integrated treatment based on surgery, combined with radiotherapy, chemotherapy, biotherapy and other new technologies, and emphasizes individualized treatment. With the increasing awareness of the disease and the diagnosis rate of early breast cancer, more and more patients can receive radical breast cancer surgery with breast preservation, sentinel lymph node localization biopsy and postoperative breast cancer reconstruction, which reduces the physical and mental burden of patients to a greater extent and results in faster postoperative recovery. For patients with locally advanced breast cancer, new adjuvant comprehensive treatment is carried out to help reduce the tumor load, lower the tumor stage and select sensitive drugs in order to improve the overall survival rate. Breast cancer prevention 1. Regular check-ups: Women over 20 years old should learn self-examination methods and have a clinical breast examination at least once every three years from 20 to 39 years old, while women over 40 years old should have a clinical examination and mammogram once a year. Mammography is generally considered to be the most effective method of detection. Note that the examination should be performed 7-10 days after the onset of menstruation each month, while high-risk groups should increase the number of examinations appropriately. 2, pay attention to diet: maintain a balanced diet, pay attention to the meat and vegetable mix, avoid greasy and fried foods, and prevent excess nutrition. Do not smoke and should use hormonal drugs under the guidance of a doctor. 3, maintain a good mood: adjust the mood, avoid excessive stress. Because of the long-term adverse emotional stimulation such as tension and anxiety, loneliness and depression, sorrow and sadness, and impatience and irritation, the dysfunction of neuroendocrine system is prone to breast cancer. 4. Proper exercise: morning running, swimming and yoga are good choices to combine work and rest and to prevent obesity.