1.Family heredity. 2. Menstrual factors. If the age of menarche is earlier than 12 years old, the risk of breast cancer is 2.2 times greater than that of menarche at 17 years old; if menopause is later than 50 years old, the risk of breast cancer increases about 1 times than that of menopause after 45 years old. 3. Excessive miscarriage. Normal natural abortion does not increase the risk of breast cancer, but repeated abortions or multiple abortions before the age of 18 can easily lead to breast diseases and increase the risk of breast cancer. 4. Breastfeeding. Breastfeeding is one of the best natural means to prevent breast cancer. Breastfeeding can reduce the risk of breast cancer by 20% to 30%, while non-breastfeeding babies after delivery will greatly increase the chance of breast cancer. 5. Poor quality of sex life. Breast disease and sex life are closely related, and sexual repression in women can increase the incidence of lobular hyperplasia and breast tumors. Domestic survey shows that 86% of women with lobular hyperplasia have never reached orgasm during sex. The older the age of first marriage, the higher the incidence of breast cancer. 6. Depression. The incidence of breast cancer is also higher among single women, women left behind, PR girls, retired female workers and some secondary school teachers, who suffer from breast diseases. This will lead to imbalance of internal environment and decrease of immunity, which will make cancer easily occur.