Anyone can develop breast cancer, but gender and youth are the main factors. The prevalence of breast cancer in men is only 1% of that in women, and women have an increased chance of developing breast cancer after middle age. The first peak of breast cancer in our women is between 45 and 50 years old and the second peak is between 60 and 65 years old. Although the exact cause of breast cancer is still uncertain, according to epidemiological findings, the following factors are closely related to breast cancer: 1. Having benign breast disease, especially those with atypical hyperplasia 2. Those who are celibate and have not had children, or those who have not had children after marriage. 3. Those who have not breast-feeding after childbirth. 4, young menarche <12 years old, or amenorrhea age >55 years old. 5.Used hormonal drugs or hormonal cosmetics. 6.Obesity, or excessive fat intake, alcoholism, smoking. 7, those who repeatedly receive various kinds of radiation (including multiple intensive radiological examinations). 8.Persons who are depressed, anxious, under pressure at work, and often angry 9.History of breast cancer or ovarian cancer in maternal family. 10.People who have had breast cancer on one side. Those who meet the above factors should pay special attention to frequent self-examination and regular screening. The best way to prevent breast cancer is to participate in screening. Breast screening refers to the act of regular screening of women aged 35 to 70 years old, in addition to the traditional breast examination and self-examination, and also the imaging examination such as X-ray or ultrasound, according to the characteristics of the high incidence of breast cancer in China. It is important to note that according to the experience of breast screening in countries around the world, screening must be done regularly and repeatedly, generally once every 18 months, and four times in a row to achieve the effect of reducing mortality. Occasional screening cannot achieve the goal of reducing mortality.