Comparison of four automated prostate-specific antigen assays for detection of recurrence after radical prostatectomy

Objectives. To compare four assays-the Abbott IMx, the Tosoh, the Chiron ACS PSA, and the Chiron ACS PSA(2)-in their ability to detect prostate-specific antigen (PSA) after radical prostatectomy. Methods. Serum samples were drawn on all men who had had a previous radical prostatectomy and who were seen in the urology clinic in March 1995. The results of each assay were compared using linear regression. Results. Twenty-two patients had an undetectable PSA by the IMx assay. The PSA was over the residual cancer detection limit (RCDL) of the Tosoh assay in 5 of these patients. The PSA was over the RCDL of the ACS PSA assay in 15 of these patients and over the RCDL of the PSA(2) assay in 2 patients. There were no patients whose PSA was less than the RCDL of the ACS PSA assay who had a measurable PSA level by any of the other assays. Conclusions. There is a difference among PSA assays in their ability to detect low levels of PSA after radical prostatectomy. The ACS PSA assay is the most sensitive, and the IMx assay is the least sensitive. (C) 1997, Elsevier Science Inc.