The etiology and development mechanism of breast cancer is very complex, and the global geographic distribution of breast cancer varies greatly. In general, it is the result of multiple factors and interactions such as genetic factors, lifestyle and environmental exposures. The risk factors for breast cancer are as follows: 1. Family history and genetic factors: There is a clear family susceptibility to breast cancer. Women with a family history of breast cancer have a 2-3 times higher risk of developing breast cancer than the general population. The risk of breast cancer is 2 times higher for women with first degree relatives or second degree relatives with breast cancer than for the general population; the risk is nearly 4 times higher for women with 3 or more first degree relatives with breast cancer. Age at menarche and age at menopause: The relative risk of breast cancer is 2.2:1 when the age at menarche is less than 12 years old compared to more than 17 years old; the risk of breast cancer increases when menopause is late and the menstrual period is more than 36 years old; the risk of breast cancer is 1 times higher when the age at menopause is greater than or equal to 55 years old compared to less than 45 years old. 3. Age at first birth and breastfeeding: The risk of breast cancer for women with first birth less than 20 years old is half of that for women with first birth later than 35 years old. Breastfeeding can reduce the risk of breast cancer by 4.3% for each year of breastfeeding. 4. Marriage: The risk of breast cancer increases by one time for unmarried people compared to married people, and the risk increases for unmarried or late married women over 30 years old, or women who have not given birth after marriage. 5. Exogenous estrogen: The risk of breast cancer increases by 15%-25% with long-term use of oral contraceptives. Hormone replacement therapy is associated with an increased risk of breast cancer and can increase the risk of invasive breast cancer by 26%. 6, ionizing radiation: Patients who receive radiation therapy; the chest is exposed to multiple radiation exposures, another example is the higher incidence of breast cancer among women in Hiroshima, Japan than in other parts of Japan, which may be related to the radioactive contamination caused by the atomic bomb explosion back then. This may be related to the radioactive contamination caused by the atomic bombing. Another example is that the incidence of breast cancer increases when the chest is repeatedly X-rayed for a long time. 7. Benign breast diseases: The risk of breast cancer is 2-3 times higher for those with fibrocystic disease and fibroadenoma. The risk of breast cancer is 1.5-2 times higher for intraductal papilloma, sclerosing adenopathy, and moderate common hyperplasia than for non-proliferative lesions. Atypical ductal hyperplasia and atypical lobular hyperplasia, the risk of breast cancer for such lesions increases 3.5-6 times. 8. Alcohol consumption: The latest study found that low to moderate ethanol intake increases the risk of breast cancer, even if 5-10g of ethanol is consumed daily, the risk of breast cancer increases by 15%; every 10g increase in ethanol intake increases the risk of breast cancer by 10%. 9. Weight and exercise: Weight gain and overweight are generally recognized as risk factors for breast cancer. Exercise may reduce the risk of breast cancer, especially in young women who have given birth. 10. Contralateral breast cancer: Those who have a history of breast cancer on one side have an increased risk of breast cancer on the opposite side. Other factors that may increase the risk of breast cancer include abortion, smoking, poor occupational environment, and chemical exposure. The wide variation in the global distribution of breast cancer strongly suggests that dietary nutritional factors may be an important factor in its development. Studies have found that soy intake may be a protective factor in the development of breast cancer. Low-fat diets may influence breast cancer risk through hormonal pathways. Fruit and vegetable intake may be associated with a reduced risk of breast cancer.