[A study on the mass screening system for prostatic diseases].

Between 1984 and 1990, a mass screening for prostatic diseases was carried out on men over 55 years old in cities, towns and villages in Toyama Prefecture, Japan. The total number of subjects examined in the primary study was 1,232, which was 17.7% of the males over 55 years old in these areas. The primary study consisted of inquiry concerning urination, digital examination of the prostate, transabdominal ultrasonography, and determination of tumor markers. A secondary study was indicated for 100 subjects (8.9%) suspected to have prostatic cancer and 169 (15%) suspected to have benign prostatic hypertrophy, but only 92 (35%) of them were actually examined. Prostatic cancer was histologically diagnosed in 3 subjects (0.3%), and benign prostatic hypertrophy was established in 56 subjects (4.5%), who were referred to urologists. Though a high percentage of the population was covered by the primary study the percentage of subjects who received the secondary study among those in whom it was indicated was low. This probably was a reason for the low detection rate of prostatic cancer. An improved system is considered to be needed to increase the efficiency of mass screening for prostatic diseases.