A mass screening for early detection of breast cancer has been carried out periodically in Nagano Prefecture since 1981 as a part of our outreach program mobilizing two vans specially designed for this purpose.
For primary screening, palpation and ultrasonographic examination are perfomed. Ultrasonography has been introduced as an auxiliary tool, because palation is not always conducted by experienced doctors.
This auxiliary diagnostic produdure has proved to be highly effective in separating out those examinees requiring thorough examinations fro those who have been found to have tumorous masses.
A total of about 25, 000 people go through the primary chechups annually, of whom 10 percent are subjected to ultrasonic examination. In 1983, 20 persons (0.08%) were diagnosed as having breast cancer. The number was 17 (0.10%) in 1981 and 16 (0.06%) in 1982. These detection rates are nearly equal to those in the “advanced” prefectures in terms of medical service.
In ultrasonographic diagnosis, Polaroid prints are used for primary screening. However, negative films are suitable for workup in the hospital. Our experience has told that in Polaroid photography, biplane scanning is necessary.