Evaluation of a mass screening of breast cancer with mammography in personnel of regional public schools

We have examined a total of 15,224 women in our hospital aiming at a mass screening of breast cancer with mammography (MMG) during the last 8 years. Subjected women were teachers or staffs of public schools in six prefectures in the Tohoku area. More than 90% of them were under 50 years old and women younger than 49 accounted for about half of them. A recall rate was 3.8%, and breast cancer was found in 55 women (0.36%) and the ratio of cancers diagnosed among recalled women was 9.5%. Twenty-one point eight percent of detected cancers were associated with calcification. The average diameter of the detected tumors in the screening group was 1.6 cm, whereas that of outpatients (controls) was 2.5 cm. Stage 0 and I cancer cases in the screening group accounted for 82.0%, whereas those in the outpatient group, 49.6%, indicating a significant increase in detection rate of early breast cancer in the screening compared to the outpatients group. However, detection rate of breast masses was 76.7% of all cases of breast tumor by means of MMG, versus 86.0% by means of physical examination. These results suggest that the mass screening by using physical examination and MMG, as well as ultrasonography, may provide a better clinical application for precise diagnosis, when it is done for working women in the regional public schools who are younger. (author)