The number of breast cancer cases among Japanese women is expected to rise 25% from now to year 2020. This is higher than the forecasted 14% growth for the US and the EU over the same period. Main causes of this dramatic increase are Japanese environmental pollution and hormonal changes. Physical inactivity and changing diet patterns among Japanese women also play a role.
Breast cancer mortality in Japan has crept up since 1999. Currently, it accounts for about 9% of total Japanese female cancer mortality cases, up from 7% in 1999. However, this percentage of breast cancer mortality versus other cancer mortalities for women is still lower than that in the US, at 15%. Late detection of breast cancer in Japan is a key reason for the rising mortality rate. Breast cancer is most common among Japanese women in their 40s.
The common breast cancer screening method in Japan is mammography. However, mammography screening in Japan is less effective in detecting breast cancer of women in their 40s, vis-à-vis women in their 50s. This is because women in their 40s have more dense breast tissues, which makes detection through mammography more difficult.
Recently, a more effective method increasingly recognized in Japan, as well as the US and Europe, is ultrasound elastography. Using tissue elasticity imaging techniques, this method is used with ultrasound devices to clinically diagnose breast diseases. Research has indicated that ultrasound elastography is more successful than mammography in distinguishing malignant from benign breast lesions. In other parts of Asia, the efficacy of ultrasound elastography for breast cancer diagnosis is believed to be in early stages of study.