The outcome of breast cancer depends more on the stage of the disease. Improving early diagnosis is the key to improving the cure rate, which can reach over 95% for ductal carcinoma in situ in early stage breast cancer, and gives more chances of breast preservation. In the early 1960s, the Health Insurance Plan of Greaster New York (HIP) used clinical breast examinations and mammograms to screen healthy people for breast cancer. From 1973 to 1980, the American Cancer Society (ACS) and the National Cancer Institute (NCI) further implemented a breast cancer screening program. In 1973-1980, the American Cancer Society (ACS) and the National Cancer Institute (NCI) further implemented the Breast Cancer Detection Demonstration Project (BCDDP), which involved 280,000 women in 29 regions. Its findings confirmed the value of breast cancer screening: regular breast cancer screening (mammograms) reduces breast cancer mortality. Today, almost all state governments in the United States have enacted legislation to cover the cost of mammograms from health insurance funds. The significance of this legislation is not only to establish the value of breast cancer screening, but more importantly to legalize screening in the name of the state. Since then, most countries such as Japan, Europe and the United States have also included breast cancer screening for women over 40 years of age into their health insurance plans. Currently, breast cancer in these countries is still increasing in incidence while the mortality rate has gained a sustained decline due to the increased detection rate of early cases brought by screening. The 1997 ACS recommended the following principles for breast cancer screening: 1 breast self-examination per month at age 18-39 years and a clinical examination once every 3 years; 1 clinical examination and mammogram per year at age 40-49 years; 1 clinical examination and mammogram per year and 1 breast self-examination per month at age 50 years and older. There is no restriction on the age of termination of screening. Since then, the American College of Radiology (ACR), ACS, and NCI have issued recommendations on breast cancer screening for women, agreeing that it is more appropriate to start breast cancer screening at age 40-49. For women with high risk factors for breast cancer, screening can be initiated before the age of 40 years with the guidance of a physician: previous breast cancer; pathologically confirmed atypical hyperplasia; ≥2 breast biopsies with a diagnosis of benign disease; carrying a breast cancer susceptibility gene with an inherited mutation; and having a first-degree relative (mother, sister, daughter) with breast cancer.