1. Hormone secretion disorder: The so-called hormone secretion disorder mainly refers to the disorder of estrogen secretion. The high incidence of breast cancer is among women aged 40 to 60. This is the age when estrogen secretion is disordered and estrogen level is high. Due to the increased secretion of estrogen in the body, the ductal epithelial cells of the breast can overgrow and become cancerous. 2. Childbirth and lactation: In recent years, a large number of surveys have proved that more women who have not given birth or who have given birth but rarely lactated have breast cancer than those who have lactated many times and for a long time. This indicates that having more children and lactating more often may increase the chance of breast cancer. 3.Fibrocystic mastopathy: As mentioned earlier, it is a kind of pre-cancerous lesion that can easily become breast cancer. 4. Genetic factors: mainly manifested in a family history of breast cancer. According to foreign information, positive family history can be in two forms: one is that the mother has breast cancer and her daughter also has breast cancer, which mostly occurs before menopause and is often bilateral; the other is that the mother has not had breast cancer, but in a family, at least two sisters have breast cancer, the incidence of breast cancer in such families is 2 to 3 times higher than that in families without family history, and this kind of breast cancer mostly occurs after menopause. Breast cancer mostly occurs after menopause and is often unilateral.