The etiology of breast cancer is not well understood. Genetic, hormonal, immune, and environmental factors may interact with each other to participate in the development and progression of breast cancer. The following are some of the more recognized risk factors. Family history and breast cancer related genes, such as BRCA-1, BRCA-2, p53, PTEN gene mutations. Reproductive factors include young age at menarche/older age at menopause/shorter menstrual cycle/older age at full-term pregnancy/less frequent births/no breastfeeding. 3.Sex hormones High estrogen level in the body or exogenous estrogen replacement therapy for various reasons / high androgen level in the body of postmenopausal women / high prolactin level in the body of postmenopausal women. 4, nutritional diet obesity / alcohol / less vegetables and other fiber-rich food 5, environmental factors radiation / oral contraceptives (controversial) / lack of physical exercise / engaged in beauty, pharmaceutical industry / certain drugs 6, other systemic diseases such as type 2 diabetes.