The prevention factors of breast cancer are as follows: 1. Low-fat diet. According to the statistics of American experts in a large number of women, they found that the incidence of breast cancer is higher in people with high-fat diet; the recurrence rate of breast cancer is also higher after surgery. 2. Vegetables, fruits, yams, mushrooms, soy products, carrots, green tea, etc. can reduce the risk of morbidity. Coffee, cholesterol, unsaturated fatty acids, black tea, vitamin E, etc. are not related to the occurrence of breast cancer. Physical exercise can reduce the incidence of breast cancer, especially for postmenopausal women. The incidence of breast cancer was found to be lower (by 50%) in those who took anti-female hormone drugs than in the control group (those who did not take drugs). However, the benefits of this treatment are offset by the increased incidence of thromboembolism, endometrial cancer and cataracts associated with long-term use of these drugs. 5. Normal sexual life has no effect on the incidence of breast cancer.