I. Promotion principles In 1997, the American Cancer Society (ACS) established the promotion principles for early detection of breast cancer, which include: 18-39 years old: monthly breast self-examination and 3-year clinical physical examination. 40-49 years old: annual clinical checkup and mammogram. Women at high risk should consult with their physicians about the need to start screening before age 40 and the interval between mammograms at age 40 and 49. Over 50 years old: Annual clinical checkup and mammogram, monthly breast self-examination. For women in China, regular screening can be recommended based on the following risk factors for breast cancer and with reference to the promotion program: 1. family history of breast cancer; 2. previous history of benign breast tumors; 3. not having children; 4. first full-term pregnancy > 30 years; 5. age of menarche < 12 years or menopause after 55 years; 6. eating excessive animal fat and being overweight after menopause; 7. long-term oral or injections of estrogen. Women at severe risk for breast cancer are those who have a significant family history of breast cancer, a first-degree relative with pre-menopausal breast cancer, or a positive gene for breast cancer. In addition, women with previous breast cancer, intraductal breast cancer, lobular carcinoma in situ, or atypical hyperplasia are also included in this category. These patients should be subjected to more stringent testing measures. Women with any abnormalities detected during regular examinations, including clinical findings of suspicious masses or imaging abnormalities, should be promptly investigated for further pathology to clarify the diagnosis.