Usefulness of proprostate-specific antigen in the diagnosis of prostate cancer.

BACKGROUND: Free prostate-specific antigen (fPSA), the minor form of total PSA, contains different molecular subforms, including BPSA and proPSA. Whereas BPSA is associated with benign prostate hyperplasia, proPSA is associated with prostate tumor. PATIENTS AND METHODS: The serum levels of PSA, fPSA and proPSA were measured using automated electrochemiluminescent immunoassays (Elecsys 2010, Roche Diagnostics) in 87 patients with prostate cancer and 138 patients with benign prostate hyperplasia. Also, we calculated the derived tests of these assays through the subtraction or the ratio between the measured tests. RESULTS: Receiver operating characteristics curves were used for comparison of the diagnostic utility of tests assessed. The biggest areas were obtained for the free/total PSA ratio (0.705), the calculated Bfree PSA/total PSA ratio (0.719) and the calculated Bfree PSA/bound PSA ratio (0. 726). CONCLUSION: Applying a multivariate logistic regression analysis, it was determined that the combination of the proPSA concentration, the proPSA/total PSA ratio and the calculated Bfreeltotal PSA ratio improves the area under the curve obtained for individual tests (0.753). ProPSA may be useful in the diagnosis of prostate cancer.

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.

[Usefulness of PSA and its fractions in the diagnosis of prostate cancer]. / Antígeno prostático específico y sus fracciones en el diagnóstico del cáncer de próstata.

BACKGROUND AND OBJECTIVE: The description of different forms of PSA has opened a new strategy in the diagnosis of prostate cancer. The measurement of the ratio between free PSA and PSA in the group of patients with a PSA level between 4 and 10 ng/ml decreases the number of negative biopsies. The aim of our study was to compare the diagnostic efficacy of PSA and PSA fractions (free PSA [fPSA] and complexed PSA [cPSA]) in the differential diagnosis between Pca and benign prostate hyperplasia (BPH). PATIENTS AND METHOD: We measured the serum levels of PSA, free PSA and cPSA in 56 patients with Pca and 94 patients with BPH. RESULTS: ROC curves were used for the comparison of tests. The biggest area under the curve (AUC) was observed for the ratios fPSA/cPSA and fPSA/PSA (0.718 and 0.712, respectively). When we compared the AUC between PSA and cPSA, then AUC for cPSA was higher than AUC for PSA (0.602 and 0.567, respectively). We observed similar results in the group of patients with PSA levels between 4 and 10 ng/ml. CONCLUSIONS: The diagnostic accuracy of cPSA is higher than that of PSA. Moreover, in the differential diagnosis between prostate cancer and BPH, the use of PSA ratios (fPSA/cPSA or fPSA/PSA) increases the diagnostic accuracy obtained with the measurement of PSA or cPSA.

Comparison of several combinations of free, complexed, and total PSA in the diagnosis of prostate cancer in patients with urologic symptoms.

OBJECTIVES: To compare the diagnostic efficacy of prostate-specific antigen (PSA) and the PSA fractions (free PSA [fPSA] and complexed PSA [cPSA]) in the differential diagnosis between prostate cancer and benign prostatic hyperplasia. METHODS: We measured the serum levels of total PSA (tPSA; Hybritech and Bayer), fPSA (Hybritech), and cPSA (Bayer) in 72 patients with prostate cancer and 128 patients with benign prostatic hyperplasia. RESULTS: Receiver operating characteristic curves were used for comparison of these tests. The greatest area under the curve was observed for the fPSA/cPSA ratio and the fPSA/tPSA ratio (0.757 and 0.754, respectively). The substitution of the fPSA/tPSA ratio with the fPSA/cPSA ratio in the diagnostic scheme of prostate cancer improved the diagnostic accuracy, with similar sensitivity and an increment in specificity (41% versus 45%). CONCLUSIONS: The fPSA/cPSA ratio ensures a reduction in negative biopsies in the PSA gray zone. We suggest substituting the fPSA/tPSA ratio with the fPSA/cPSA ratio for patients with a PSA level between 4 and 10 ng/mL.