Common Causes of Breast Cancer Although the causes of the vast majority of breast cancers are not known, many risk factors for the disease have been identified. Environmental factors and lifestyle have a greater impact on the incidence of breast cancer than genetic factors, both of which are modifiable and therefore important in preventing the development of breast cancer in women. These risk factors include: 1. Age: In women, the incidence rate increases with age. It is rare before the first menstruation and rare before the age of 20, but the incidence rate increases rapidly after the age of 20 and is higher from 45 to 50. Early menarche (<13 years old), late menopause (>55 years old), late first birth (>35 years old) or no childbirth are associated with the development of breast cancer. Genetic factors: The risk of breast cancer in first-degree relatives with a history of breast cancer (mother with breast cancer or two first-degree relatives with breast cancer) is two to three times higher than that of the normal population. 3. The relationship between benign breast diseases and breast cancer is difficult to determine, such as cystic hyperplasia, fibroadenoma, intraductal papilloma and so on. Most of them believe that high epithelial hyperplasia or atypical hyperplasia in breast lobules may be related to breast cancer. 4. Excessive nutrition, obesity, excessive intake of high protein and high fat diet, alcohol consumption and smoking may increase the chance of breast cancer. Experts remind that over-nutrition and obesity in adolescence can increase the risk of breast cancer, so prevention of breast cancer should start at a young age. Proper diet during childhood is an aspect of breast cancer prevention that cannot be ignored. Children should refrain from high-fat and high-protein foods such as chocolate, ice cream and hamburgers as much as possible, and they should not take supplements blindly. 5. Long-term estrogen supplementation in postmenopausal women and indiscriminate use of oral steroid hormone contraceptives by women of childbearing age may increase the risk of breast cancer. Some of the usual oral contraceptives do not increase the risk of breast cancer. 6. Mental depression and excessive stress. According to the survey, introversion and long-term mental depression make people more and more stressed, and when this stress is not released it will affect the body, thus leading to the acidification of the physique. Unhappy life in early stage is an important factor leading to cancer. Young women in urban areas face intense competitive pressure, and their spirits are in a state of stress and tension for a long time, which leads to emotional instability and disharmony. These mental factors together with bad life and work style cause further damage to breasts. 7.Other, such as occupational radiation exposure, indiscriminate use of drugs and health care products, etc. According to the survey report published by the National Office of Cancer Control, the incidence rate of breast cancer in China’s urban population is significantly higher than that of rural population; large cities are higher than medium and small cities, which in turn are higher than rural areas. Within the same region, the incidence rate of people with high education level and high income level is higher than those with low education level and low income level, and white-collar professional women are higher than ordinary women.