The occurrence of breast cancer is related to the following factors: 1. Hormones: Breast cancer is related to the imbalance of the endocrine balance of human body, among various endocrine factors, the most important ones are estrogen and progesterone. The age of breast cancer is 40-60 years old, which is the time when women’s estrogen secretion is imbalanced 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. Estrogen is a “double-edged sword”, which can indeed prolong women’s “puberty”, but it also brings about hyperplasia of ductal epithelial cells in the breast and even carcinogenesis. 2. Menstruation and marriage: Epidemiological studies show that early menarche and late menopause are two risk factors for breast cancer. Women who do not have children or have children but rarely breastfeeding have more breast cancer than women who breastfeed for a long time. This indicates that having less children and breastfeeding may increase the chance of breast cancer, and that childbirth and breastfeeding have a protective effect on the occurrence of breast cancer. 3. Unhealthy lifestyle: introverted personality, long-term mental depression and unhappy early life are important factors leading to cancer. Women white-collar workers who work in office for a long time, sit more and move less, lack of exercise, and face fierce competitive pressure, mental long-term stress and tension, resulting in emotional instability and unrest, these bad lifestyles of work, which cause further damage to the breast, also increase the chance of breast cancer. 4. Diet: Diet and breast cancer have a certain relationship, high energy and high fat diet can easily lead to obesity, and obese women have a great chance to suffer from breast cancer. After the standard of living of some people has improved, the unscientific and unhealthy “high-calorie, high-fat” diet has resulted in a much higher incidence of breast cancer. 5, genetic factors: mainly in the family history of breast cancer. It has been found that women whose mothers had bilateral breast cancer before menopause have 9 times the risk of breast cancer than the average woman, and the average age of breast cancer in the second generation of breast cancer patients is about 10 years earlier than the average person. The average age of the second generation of breast cancer patients is about 10 years earlier than that of the general population. Women who have sisters with breast cancer have three times the risk of the general population. It is important to emphasize that breast cancer is not directly inherited, but is a “cancer quality” inheritance, and relatives of breast cancer patients are not necessarily affected by breast cancer, but are more likely to develop breast cancer than the general population.