Breast cancer is the most common and most frequent malignant tumor in modern women, with about 1.3 million women diagnosed with the disease and 500,000 women dying from it every year worldwide. Currently, the incidence of breast cancer is increasing rapidly in many cities in China, which has attracted close attention. The incidence of breast cancer is related to many complex factors, such as higher intake of high-fat and low-fiber diet, postmenopausal weight gain, smoking, radiation exposure, adverse stimuli such as pesticides, and genetic factors. Recent studies have further revealed that the occurrence of breast cancer is very closely related to the level of estrogen that accompanies women throughout their life, and there are many risk factors in menstruation, marriage, childbirth and sex. Menstruation: Early menarche (before the age of 12), late menopause (after the age of 50) and long menstrual period (more than 35 years) are all recognized risk factors for the development of breast cancer. Some studies have reported that the risk of menarche is 2.2 times higher for those with menarche earlier than 13 years old than for those with menarche older than 17 years old; the risk of menarche is 1 times higher for those with menarche older than 55 years old than for those with menarche younger than 45 years old. The incidence of breast cancer is significantly higher in women who are celibate, unmarried, unpregnant or with their first child older than 30 years old than in women who are normally married and have children. Women who give birth but do not breastfeed, or who breastfeed for a short period of time, or who breastfeed with only one breast, may also have an impact on the development of breast cancer. Therefore, proper breastfeeding after childbirth can keep the mammary glands open and have a preventive effect on the occurrence of breast cancer. If a woman rarely breastfeeds or never breastfeeds, the risk of breast cancer increases significantly due to breast accumulation. Sexual life: The quality of sexual life between husband and wife directly affects the physical health of the breast. In recent years, the incidence of lobular hyperplasia and benign and malignant tumors of the breast has increased rapidly, which has attracted the attention of the medical profession. A special domestic survey found that 86% of women suffering from lobular hyperplasia of the breast never had an orgasm during sex. If women are always sexually excited but cannot reach orgasm, their bodies will feel extremely uncomfortable, and the unreleased sexual tension will easily turn into cramps and pain, which will over time produce psychological and pathological “depression” and lead to lesions of breast tissue. A study on the psychological characteristics of breast cancer patients also shows that the degree of depression and anger in breast cancer patients is higher than that of healthy people. 4. Abortion: Repeated abortions can increase the likelihood of breast cancer in women. A study showed that spontaneous abortion does not increase the risk of breast cancer, while women who had an abortion before the age of 18 had a 110% higher risk than those who did not have an abortion. This is because after each abortion, the pregnancy is abruptly interrupted and the hormone level in the body suddenly drops, causing the newly developed mammary glands to suddenly stop growing, making the alveoli smaller or disappearing, and the mammary glands to recover. This recovery is usually incomplete and can easily cause breast lumps and pain, which can lead to breast diseases and repeated breast lesions can become a cause of breast cancer. Therefore, modern women should raise their awareness of self-care and advocate late marriage and late childbirth, but not too late, women should preferably get married before 28 years old. They should promote a scientific lifestyle such as breastfeeding, reasonable diet and physical exercise, and pay attention to keep an open mind, avoid depression and anger, and maintain good physical and mental health. All these are essential to prevent and reduce the incidence of breast cancer.