[Usefulness of the percentage of free prostatic specific antigen in the differential diagnosis between benign prostatic hyperplasia and 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.