Breast cancer is one of the leading causes of cancer death among women. The risk of breast cancer typically increases with age in most countries. The chief exception is Japan, where the incidence of breast cancer increases in women aged 30 to 50 years old, peaks at the age of 50, and then declines.¹

Early detection can improve cancer survival and simplify patients’ treatment. This has led to the introduction of screening programs in many countries so that signs of breast cancer can be detected at an early stage.

Mammography is currently used routinely in population based screening programs to check for signs of breast cancer in women aged 50 years and older. The technique is relatively simple, cost-effective, and has been shown to reduce mortality by more than 20%. Some studies show a reduction in mortality of up to 30% or even 40%.^2-5

The sensitivity of mammography is, however, lower in younger women and in Asian women. Women in these groups tend to have dense breasts, but inherent limitations in mammography limit its ability to depict masses in dense breast tissue. This poses a significant problem to breast screening programs in Japan. Not only do Japanese women tend to have dense breast tissue, but the incidence of breast cancer is also higher in younger Japanese women, particularly those in the 40- to 49-year-old age group. This has prompted manufacturers and government authorities to seek out a more suitable imaging modality, or combination of modalities, to deliver breast care in Japan.