Comparisons of the various combinations of free, complexed, and total prostate-specific antigen for the detection of prostate cancer

Objectives: We compared the ability of three prostate-specific antigen (PSA ) ratios - free-to-total PSA ratio (fPSA/tPSA), free-to-complexed PSA ratio (fPSA/cPSA), and complexed-to-total PSA ratio (cPSA/tPSA) - to distinguish prostate cancer from benign prostatic hyperplasia (BPH), Methods: We tested 258 consecutive patients who underwent transrectal ultra sound-guided prostate needle biopsy because of an abnormal digital rectal e xamination or a Tandem-R PSA of > 4.1 ng/ml. Free PSA (fPSA) and total PSA (tPSA) were measured by Tandem-R assay. alpha(1)-Antichymotrypsin-complexed PSA (cPSA) was measured by Markit-M PSA-ACT assay. Results: Of the 258 patients, 204 had BPH, and 54 had prostate cancer. The specificity at 96% sensitivity for fPSA/tPSA, fPSA/cPSA, and cPSA/tPSA was 23, 25, and 33%, respectively. Of 162 patients with tPSA between 4.1 and 10 .0 ng/ml, 132 had BPH and 30 had prostate cancer. The specificity at 96% se nsitivity for f/tPSA, f/cPSA and c/tPSA was 32, 44, and 41%, respectively. There was no significant difference in the area under the receiver-operatin g characteristic curves among fPSA/tPSA, fPSA/cPSA, and cPSA/tPSA in the ov erall PSA range or in tPSA between 4.1 and 10.0 ng/ml. Conclusion: fPSA/tPSA, fPSA/cPSA, and cPSA/tPSA did not differ in their abi lity to distinguish prostate cancer from BPH. Copyright (C) 2000 S. Karger AG, Basel.