Clinical usefulness of assays for complexed prostate-specific antigen

Tests for the tumor marker prostate-specific antigen (PSA) vary widely in specificity and sensitivity. Use of an assay that tests the complexed form of PSA (cPSA) results in improved specificity and sensitivity. By improving specificity, similar results are obtained by cPSA compared with use of the free-to-total PSA ratio but are measured by a single analyte instead of two. Assays for cPSA can serve as a substitute for total PSA in all current applications.