1.1.3　Screening for Breast Cancer

Mammography is currently the most important and effective method for the diagnosis of breast cancer，especially for the early detection of breast cancer.It is also the preferred method of breast cancer screening recognized by many developed countries in Europe and America.In a meta-analysis of randomized controlled trials based on mammography screening，mammography reduced breast cancer mortality in women by 24 to 48 percent.［14］In the 2019 guidelines for breast cancer screening issued by the American college of physicians，it is recommended to have mammography screening every year for women aged 45 to 54，every two years for women aged 55 and above or continue to have mammography every year.As long as the woman is healthy and has a life expectancy of more than 10 years，she should continue to have mammography screening.For most women between the ages of 40 and 49，mammography has the potential to do more harm than good.［15］The NCCN panel recommends longterm annual mammograms starting at age 40.［16］As Asian female breast more belong to the type dense breast，breast cancer starts at peak between 40～50 years old，the incidence peak earlier than the west 5 10 years old.The 2019 guidelines for female breast cancer screening of China anti-cancer association recommend that breast ultrasound screening should be performed once a year for women aged 40 to 44 years who have no family history of early breast cancer or do not carry pathogenic genetic mutations of breast cancer.Mammograms are recommended every two years for women aged 45 to 69 with general risk.Women aged 69 years or older who are healthy and have a life expectancy of more than 10 years，opportunistic screening is recommended.［17］(https://www.daowen.com)