Breast cancer is the most common malignant tumor in women, mostly occurring in women around the age of 40-60 years old during menopause, while breast cancer in men is less common than in women, with a peak age between 50-60 years old. The etiology of breast cancer is not yet clear. Factors related to it: 1. Endocrine factors: Estrone and estradiol have a direct relationship with the development of breast cancer. Progesterone is considered to have both carcinogenic and carcinogenic effects, and prolactin also promotes the development of cancer. Clinically, the incidence rate gradually increases after the age of 20, and is higher at the age of 45-50. 2. Menstruation and marital factors: the incidence of menarche is earlier than 12 years old, menopause is later than 55 years old, and the incidence of infertility is higher, and clinically, the incidence of the first full-term birth is significantly higher than that of the first birth before 20 years old. Family genetic history: If there are breast cancer patients in first-degree relatives, their family members are often the high-risk group, and their risk is 2-3 times higher than that of the general population. 4.Benign breast diseases are related to it. 5, Diet, obesity: there is a significant relationship between fat intake and its mortality, especially in postmenopausal women. 6.Environmental factors, lifestyle: bad habits such as staying up late for a long time, frequent exposure to ionizing radiation, chemical substances and other factors are related to breast cancer. The cause of breast cancer is not yet completely clear, but it can be prevented by targeting related factors in daily life.