Breast cancer high-risk group refers to: (1) those with obvious genetic predisposition to breast cancer (e.g. BRCA1/BRCA2 gene mutation carriers among relatives); (2) those with previous moderate to severe atypical hyperplasia of breast ducts or lobules or lobular carcinoma in situ; (3) those with previous history of chest radiotherapy. 1. Screening: Screening age should be advanced (20~40 years old) for those with high risk of breast cancer, and screening interval should be once a year, using mammography and ultrasound combined with clinical examination and MRI. 2. Drug prevention: (1) Tamoxifen is the first drug approved by FDA for breast cancer prevention: research results show that tamoxifen can effectively reduce the risk of breast cancer in high-risk groups by 29%, and can reduce the incidence of hormone receptor-positive breast cancer by 34%; the effect on hormone receptor-negative patients is not obvious. Side effects: Tamoxifen increases the risk of endometrial cancer, non-melanoma skin cancer, and adverse effects such as pulmonary artery embolism and DVT. (2) Aromatase inhibitors are an effective option for prevention of postmenopausal breast cancer in high-risk groups: studies have shown that anastrozole reduces the risk of breast cancer in high-risk groups by 53%, the incidence of hormone receptor-positive breast cancer by 58%, and the incidence of ductal carcinoma in situ by 70%, as well as reducing the risk of skin cancer by 47% and the risk of gastrointestinal tumors by 67%. The definite efficacy and good safety profile of anastrozole support its use for endocrine prophylaxis in postmenopausal women at high risk. 3. Surgery: prophylactic mastectomy, a procedure currently not considered to completely prevent the development of breast cancer.