[The present status of convergence in PSA reference values--from the surveillance in the Tokai-Hokuriku district]

The number of patients with prostatic cancer is recently increasing in Japan and it is well known that serum PSA determination is routinely used as a tumor marker of prostatic cancer. However, the reference values of PSA are widely varied, because the reactivities of the antibody to free PSA and ACT-PSA are different in each kit. Thus, there is no compatibility among values determined by available kits. In this study, we sent a questionnaire on PSA determination to 180 hospitals with more than 200 beds. The recovery rate to the questionnaire was 80.5% (145/180) and the determination was performed in house at 47 hospitals out of 145. Stamey in Stanford University recommended to set the ratio of complex PSA to free PSA 9:1 in the reference material. It is expected that PSA ad hoc committee in Japan reported that the inter-kit variability is becoming small. It can be said that the standardization for PSA determination is progressing. To discriminate prostatic cancer from benign prostatic hypertrophy, free PSA ratio or complex ACT-PSA is recommended. Further accumulation of data on PSA will be necessary to confirm this matter.