Value of the free to total prostate specific antigen ratio and prostate specific antigen density for detecting prostate cancer in Japanese patients.

Abstract

This study evaluated the free to total serum prostate specific antigen (f/t PSA) ratio and prostate specific antigen density (PSAD) in detecting prostate cancer in Japanese males with a PSA level between 2.5 and 20.0 ng/mL in a community-based urology practice. Twenty-six patients with clinically localized prostate cancer and 44 patients with histologically-proven benign prostatic hyperplasia (BPH) were studied. The serum levels of free PSA (fPSA) and total (t) PSA were determined using a chemiluminescent enzyme immunoassay. The f/t PSA ratio was calculated by dividing the fPSA value by the total PSA value and was compared with the PSA and PSAD via the receiver operating characteristic (ROC) curves. Patients with prostate cancer had a significantly lower f/t PSA ratio than patients with BPH. The PSAD was a superiordiagnostic tool over PSA (P< 0.01) when analyzed by ROC curves. The f/t PSA ratio was also superior to PSA, but lacked significance (P=0.12), and similarly, the PSAD was superior, but not significant, to the f/t PSA ratio. Using a cut-off value of 0.19, the PSAD had a sensitivity of 81% and a specificity of 82%. With a cut-off value of 14.0%, the f/t PSA ratio had a sensitivity of 81% and a specificity of 66%. This study showed that PSAD alone improved cancer detection significantly better than PSA. However, it is still unclear whether the f/t PSA ratio is superior to PSA or PSAD in the discrimination between BPH and prostate cancer in Japanese male patients.