Mass screening program for prostatic cancer in Japan.

Because the idea of "mass screening" in Japan is based upon the concept of "groupism", a fundamental feature of Japanese society, it is very different from the idea of "screening" in Western countries, which arises from an "individualistic" concept. The prevalence of prostatic cancer in Japan remains lower than that in Western countries but it has recently shown a great increase. In this situation, a mass screening program for prostatic cancer, using prostate-specific antigen (PSA) for the primary study, is thought to be promising in Japan. To exclude false-positive cases in the "gray zone" of PSA values, transrectal power Doppler sonography is remarkably effective.