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.