Current status of mammographic screening in western countries and Japan

Breast cancer screening by clinical breast examination (CBE) was introduced into public health services in 1987 without any evidence on its effectiveness. It was based on the presumption that any early detection is always beneficial. A case-control study, which was conducted to evaluate the effectiveness of breast cancer screening by CBE, demonstrated that CBE would lack its effectiveness (Odds ratio; OR=0.93), although it might be effective for asymptomatic population (OR=0.56). In 1998 the Research Group for Evaluating the Effectiveness of Cancer Screening Programs in Japan reported that the effectiveness of breast cancer screening by CBE has not yet been shown epidemiologically. According to the 1995 survey by the International Breast Cancer Screening Network (IBSN), all the 22 countries except Japan introduced mammography in their screening programs. It is necessary to consider an introduction of mammographic screening to reduce breast cancer mortality in Japan.