The role of free to total prostate-specific antigen ratio for prostate cancer in screening patients with total serum levels between 4 and 20 ng/ml

We retrospectively tried to determine if the free to total prostate-specific antigen (f/t PSA) ratio could improve the specificity of PSA in prostate cancer screening of patients with total serum levels between 4 and 20 ng/ml.Two hundred ninety-five patients with serum PSA levels from 4 to 20 ng/ml had undergone sextant prostate needle biopsy. Each patient had no prior history of prostate cancer, acute urine retention, or prostatitis. Prebiopsy free PSA values were measured in 155 patients. Total PSA levels were determined with the AxSYM enzyme-linked immunosorbent assay. Free PSA levels were measured with the AxSYM microparticle enzyme immunoassay.Mean f/t PSA ratios were 0.114+/-0.004 in men of the cancer group and 0.161+/-0.008 in men of the benign group (p0.002). Based on the analysis of sensitivity and specificity in relation to f/t PSA ratios, use of the 18% cutoff point could detect 89% of cancer cases, and at the same time could avoid 35% of unnecessary prostate biopsies. The areas under the receiver-of-characteristic curve for f/t PSA ratio and total PSA were 0.649 and 0.545, respectively.Serum f/t PSA ratios were significantly lower in patients with prostate cancer than in patients with benign disease. The determination of an appropriate f/t PSA ratio should be based on the generated data such as that demonstrated in this study in order to improve diagnostic accuracy and specificity for patients with equivocal PSA values and to avoid conducting unnecessary prostate biopsies.