Abstract
The urgent objective of breast cancer screening is to reduce the incidence of death due to breast cancer, which has recently been increasing in Japan. Since women in their 5th decade have the highest incidence of breast cancer in Japan, we must think about the importance of screening participants in younger age brackets.
Mammographic breast cancer screening has yielded good results due to the sustained effort of the Central Committee for Quality Control to increase its quality and availability. However, screening of younger women has limitations of sensitivity because of diffusely or unevenly dense breast tissue. Therefore we consider that combined use of ultrasonography is important for screening of young women.
We reviewed the results of our combined mammographic and ultrasonographic screening carried out on a total of 91,882 participants in Tochigi prefecture during a 6-year period from 2000 through 2005. The contribution rates of mammography to the breast cancer detection rates in women in their 5th and 6th decades were 82% and 64%, respectively, and those of ultrasonography were 72% and 71%, respectively. The corresponding figures for mammography in women in their 7th and 8th decades and over were 85% and 89%, respectively, while those for ultrasonography were 63% and 59%, respectively. These results imply that combined use of both mammography and ultrasonography works well by compensating for each other's limitations for women in their 5th and 6th decades.
For women in their 4th decade, the rate of breast cancer detection was low, and the ratio of the effect relative to mass screening cost was low. For women aged between 35 and 39, however, the incidence of breast cancer apparently increased and reached an incidence similar to those for other malignancies. Therefore breast cancer screening for younger women is of social importance, and introduction of ultrasonography to screening of this population is necessary.
