The clinical value of free PSA and total PSA ratio

The ratio of free prostate specific antigen (FPSA) to total prostatic specific antigen (TPSA) in serum is lower in malignant prostatic disorders than benign ones. This ratio can be used to distinguish the patients with cancer from the patients without cancer in whom TPSA value is between 4-10 ng/mL. But there is not an absolute cutoff value. We evaluated the FPSA/TPSA ratio cutoff as 0.15 in detecting cancer for our patients. 236 men with various urologic symptoms were evaluated with digital rectal examination (DRE), FPSA and TPSA measurements. The patients with total PSA value under 4 ng/mL were biopsied if they had positive DRE and/or a FPSA/TPSA ratio lower than 0.15. All the patients with TPSA value higher than 4 ng/mL were also biopsied. ln the group of patients with TPSA value between 4 and 10 ng/mL the predictive Value of TPSA was 21%, but the predictive value of FPSA/TPSA ratio of 0.25 was 78% maintaining at least 90% sesitivity. In DRE negative and TPSA value between 4-10 ng/mL patients the ratio of FPSA/TPSA can allow us to eliminate a lot of unnecessary biopsies with minimal loss of cancer patients.