RESUMEN
<p><b>OBJECTIVE</b>To evaluate the use of free/total prostate-specific antigen ratio (fPSA/tPSA ratio) in improving the early diagnosis of prostate cancer.</p><p><b>METHODS</b>fPSA/tPSA ratio in the serum was analyzed prospectively in 187 men with tPSA ranging between 4.0 and 20.0 microg/L. All of them underwent ultrasound-guided sextant prostatic biopsies. Sensitivity, specificity, positive and negative predictive values were calculated by SPSS 10.0 software.</p><p><b>RESULTS</b>Prostate cancer detection rates were 18.1% and 22.5% when tPSA was within the ranges of 4.0-10.0 g/L and 10.0-20.0 g/L respectively. fPSA/tPSA ratio was more significant than tPSA in all the men. When the cut-off value of fPSA/tPSA ratio was set at 0.25, 90.5% and 87.5% of cancers could be detected; and 26.7% and 11.3% of biopsies could be avoided within the tPSA ranges of 4.0-10.0 g/L and 10.0-20.0 g/L, respectively.</p><p><b>CONCLUSION</b>The use of fPSA/tPSA ratio can improve prostate cancer detection and reduce unnecessary biopsies when tPSA is within the range of 4.0-10.0 microg/L and 10.0-20.0 microg/L.</p>