Complexed prostate-specific antigen for the detection of prostate cancer.

BACKGROUND The description of a new method for the measurement of complexed prostate-specific antigen (cPSA) offers a new approach to the diagnosis of prostate cancer. PATIENTS AND METHODS We measured PSA (Hybritech and Bayer), free PSA (Hybritech) and complexed PSA (Bayer) in 72 patients with prostate cancer and 128 with benign prostate hyperplasia. RESULTS AND CONCLUSION We found an increase of sensitivity using 25 and 7 ng/mL as cut-offs for cPSA in relation to total PSA using as cut-offs 4 and 10 ng/mL (96 and 36% vs. 92 and 35.5%). Similar differences were found for specificity (78% and 31% for cPSA vs. 73% and 29% for total PSA). Therefore, we defined a gray zone for patients with cPSA between 2.5 and 7 ng/mL for which the measurement of the free/complexed PSA ratio saves an important number of negative biopsies maintaining a higher sensitivity.