The incidence rate of breast cancer in the United States is above 100/100,000, and nearly 200,000 cases of breast cancer are diagnosed each year. Our 2014 tumor registration data in Henan Province suggests that the incidence rate of breast cancer in the province also reached 39.38/100,000, although it is still far lower than that of developed countries, but breast cancer is still the number one incidence rate of female malignant tumors. The main reasons are as follows 1. Genetic factors: About 5-10% of breast cancer is caused by genetic factors, the main relevant mutated genes are BRCA1 and BRCA2, and the risk of developing breast cancer is 2-3 times higher in the immediate female relatives of breast cancer patients. Reproductive factors: Early menarche, late menopause, short menstrual cycle, few or no births, no breastfeeding, all these reproductive factors are associated with increased risk of breast cancer. 3. Dietary factors: Diets that increase the risk are: high-fat diet, alcohol, and high-sugar diet. Those that can reduce the risk are: soy products, fruits and vegetables, and tea. The effect of coffee is not clear. 4. Other factors: ionizing radiation, environmental pollution, obesity can increase the risk, and exercise can reduce the risk. Factors that have been shown not to increase the risk of breast cancer (which may cause misconceptions) 1. Spontaneous and induced abortion: Several studies have confirmed that abortion does not increase the risk of breast cancer. 2. Oral contraceptives: Several studies have confirmed that oral contraceptives do not increase the risk of breast cancer, but a few studies have suggested that contraceptives may increase the risk in young people under the age of 35. 3. Postmenopausal hormone replacement therapy: This is more controversial and different medication may be different for different groups of people. 4. Silicone implants: No increased risk.