1, age: in women, the incidence rises with age, rare before the first menstruation, also rare before 20 years old, but the incidence rises rapidly after 20 years old, 45-50 years old is higher, but is relatively flat, the incidence continues to rise after menopause, to about 70 years old reaches its peak, the mortality rate also rises with age, the mortality rate gradually rises after 25 years old, until old age always keep rising trend. 2.Hereditary factors: Women with a history of breast cancer in the first degree of direct family members have 2~3 times higher risk of breast cancer than the normal population. 3. Other breast diseases. Age of menarche: The risk of menarche is 2.2 times higher than that of women older than 17 years old. 5.Age of menopause: The risk of menopause is increased for those who are older than 55 years old than those who are younger than 45 years old. 6. Age of first pregnancy: the risk increases gradually with the postponement of the age of first birth, and the risk is higher for those who have their first birth after 35 years old than for those who have no history of childbirth. 7. Post-menopausal estrogen supplementation: Long-term use of estrogen during menopause may increase the risk of breast cancer. 8.Oral contraceptive pills. 9. Food: Especially fatty diet may increase the risk of breast cancer. 10.Drinking alcohol. 11. Weight gain may be an important risk factor for breast cancer in postmenopausal women. 12.Long-term smoking. 13.Ovarian function The breast is regulated by ovarian hormones. Estrogen is the basic stimulator of breast development and one of the prerequisites for breast tumor development. It is believed that the abnormal increase of estrone and estradiol and the lack of estriol is one of the causes of breast tumor, which has been supported by clinical examination and proved by animal experiments. Moreover, male breast tumors are rare, about 1% of female patients, which also indicates that it may be related to the absence of ovarian hormones in men. Secondhand smoke can also induce breast cancer, and data show that breast cancer has become the most prevalent cancer. Secondhand smoke is one of the many causes of breast cancer. In the first half of this year, the State of California issued a decree declaring secondhand smoke to be a “toxic gas”. At the same time, the official survey report shows that in the case of passive smoking, the incidence of female breast cancer will increase by 68% to 120%. Canadian research also shows that among women with no history of smoking, a 27% increase in breast cancer risk is associated with long-term exposure to secondhand smoke. Researchers say that smoking has been found to cause genetic mutations in fluid nipple secretions in non-lactating women. Those women who were chronic passive smokers had much higher levels of nicotine concentrations in nipple fluid secretions than in their blood. Long-term accumulation can easily lead to breast cancer. Although many women know that second-hand smoke is harmful to their bodies, many do not know that second-hand smoke is also one of the “culprits” of breast cancer. This reporter conducted a survey online, and the respondents were 20 working women. From the survey results, although most women are aware of the danger of breast cancer, they do not pay enough attention to it. Almost all women are not aware of the fact that “second-hand smoke can cause breast cancer”. In fact, in recent years, the number of women suffering from breast cancer in China has been increasing, and more than 10,000 patients die from breast cancer every year, especially in some economically developed big cities, breast cancer is the first malignant tumor among women. To prevent breast cancer, not only women themselves should pay attention to it, but also the whole society should pay attention to it. Creating a healthy “smoke-free” environment, whether in public or at home, is not only a reflection of caring for women’s health, but also an effective way to build a fortress of health for yourself.