[Comparison of 3 assay kits of prostate specific antigen in serum of prostatic cancer].

The serum prostate specific antigen (PA) of the patients with prostatic cancer were determined with 3 assay kits, the Diagnostic Products Cooperation (DPC) kit, the Eiken kit and the Dainippon Pharmaceutical Co. (MARKIT F) kit. The first 2 assay kits involve radioimmunoassay and the latter EIA. For comparison, prostatic acid phosphatase (PAP) and gamma-seminoprotein (gamma-Sm) were determined using an Eiken kit and Chugai kit. Efficiency of the DPC kit, Eiken kit and the MARKIT F kit for untreated prostatic cancer was 26, 25 and 36%, respectively. The PA level measured using the Eiken kit and the MARKIT F kit both well correlated to the PAP level, but with the DPC kit correlation was slightly low. The PA level measured using the 3 different kits correlated poorly with the gamma-Sm level. The PA values obtained with 3 different assays from patients with prostatic cancer were highly correlated, but showed great differences in the values measured. When the standards used in the DPC kit were analyzed by the Eiken kit, the DPC standards as measured by the Eiken kit had only about half of their assigned values. The same standards were analyzed by the MARKIT F kit, the standards yielded measured values about one third of their assigned values. When the standards used in the MARKIT F kit were analyzed by the Eiken kit, the MARKIT F standards yielded measured values about 2.5 fold of their assigned values. The differences between the values obtained with the 3 assay kits presented a serious problem in clinical use of PA. Standardization of these assay kits will be awaited.