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Probability of prostate cancer detection based on results of a multicenter study using the AxSYM free PSA and total PSA assays

      Abstract

      Objectives. The determination of the percentage of free prostate-specific antigen (%fPSA) enhances the specificity of prostate cancer (CaP) detection. This study was undertaken to assess the performance of %fPSA in differentiating benign prostate disease from CaP and to determine the CaP probability estimates using the AxSYM Free PSA and AxSYM Total PSA assays.
      Methods. In this prospective study, 297 men, 50 years old or older, with a total PSA level between 4 and 10 ng/mL and a nonsuspicious digital rectal examination were enrolled at 10 clinical sites. All subjects underwent at least sextant prostate biopsies to establish the diagnosis. fPSA and total PSA (tPSA) levels were determined using the AxSYM Free PSA and AxSYM Total PSA assays. Percent fPSA values were compared with tPSA values to determine the appropriate cutoffs for prostate biopsy and to calculate the CaP probability estimates.
      Results. The strongest predictor of CaP in a logistic regression model was %fPSA (odds ratio 2.29), which contributed significantly more than age or tPSA to the predictive model. In this study population, a %fPSA cutoff of 26.4% would have detected 96% of subjects with CaP (sensitivity) and would have eliminated 27.4% of unnecessary biopsies (specificity). CaP probability estimates ranged from 9% to 69% and increased as the %fPSA value decreased. Men with a %fPSA level of 10% or lower had a 69% probability of CaP, and men with a %fPSA level of greater than 26% had a 9% probability of CaP.
      Conclusions. Percent fPSA values can help differentiate CaP from benign prostate disease and reduce unnecessary biopsies in 27% of men 50 years old or older whose digital rectal examination was normal and whose tPSA level was between 4 and 10 ng/mL. A %fPSA result can assist the physician and patient in determining the probability of CaP and assessing the need for prostate biopsy.
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      References

        • Christensson A.
        • Laurell C.-B.
        • Lilja H.
        Enzymatic activity of prostate-specific antigen and its reactions with extracellular serine proteinase inhibitors.
        Eur J Biochem. 1990; 194: 755-763
        • Lilja H.
        • Christensson A.
        • Dahlen U.
        • et al.
        Prostate specific antigen in serum occurs predominantly in complex with alpha 1-antichymotrypsin.
        Clin Chem. 1991; 37: 1618-1625
        • Christensson A.
        • Björk T.
        • Nilsson O.
        • et al.
        Serum prostate specific antigen complexed to alpha 1-antichymotrypsin as an indicator of prostate cancer.
        J Urol. 1993; 150: 100-105
        • Vashi A.R.
        • Wojno K.J.
        • Henricks W.
        • et al.
        Determination of the “reflex range” and appropriate cutpoints for percent free prostate-specific antigen in 413 men referred for prostatic evaluation using the AxSYM system.
        Urology. 1997; 49: 19-27
        • Catalona W.J.
        • Smith D.S.
        • Wolfert R.L.
        • et al.
        Evaluation of percentage of free serum prostate-specific antigen to improve specificity of prostate cancer screening.
        JAMA. 1995; 274: 1214-1220
        • Chen Y.-T.
        • Luderer A.A.
        • Thiel R.P.
        • et al.
        Using proportions of free to total prostate-specific antigen, age, and total prostate-specific antigen to predict the probability of prostate cancer.
        Urology. 1996; 47: 518-524
      1. Partin AW, and Oesterling JE (Eds): The Clinical Usefulness of Percent Free Prostate-Specific Antigen (Special Issue). Urology 48(suppl 6A): 1996.

        • Catalona W.J.
        • Partin A.W.
        • Slawin K.M.
        • et al.
        Use of the percentage of free prostate-specific antigen to enhance differentiation of prostate cancer from benign prostatic disease.
        JAMA. 1998; 279: 1542-1547
        • Woodrum D.L.
        • Brawer M.K.
        • Partin A.W.
        • et al.
        Interpretation of free prostate specific antigen clinical research studies for the detection of prostate cancer.
        J Urol. 1998; 159: 5-12
        • Rittenhouse H.G.
        • Finlay J.A.
        • Mikolajczyk S.D.
        • et al.
        Human kallikrein 2 (hK2) and prostate-specific antigen (PSA).
        Crit Rev Clin Lab Sci. 1998; 35: 275-368
        • Dowell B.
        • Friese J.
        • Rapp J.
        • et al.
        Development of the Abbott AxSYM Free PSA and Total PSA assays.
        Clin Chem. 1996; 42: S265-S705
        • Woodrum D.
        • York L.
        Two-year stability of free and total PSA in frozen serum samples.
        Urology. 1998; 52: 247-251
        • Fiore M.
        • Mitchell J.
        • Doan T.
        • et al.
        The Abbott IMx TM automated benchtop immunochemistry analyzer system.
        Clin Chem. 1988; 34: 1726-1732
        • Stamey T.A.
        Some comments on progress in the standardization of immunoassays for prostate-specific antigen.
        Br J Urol. 1997; 79: 49-52
        • DeLong E.R.
        • DeLong D.M.
        • Clarke-Pearson D.L.
        Comparing the areas under two or more correlated receiver operating characteristic curves.
        Biometrics. 1988; 44: 837-846
        • Agresti A.
        Analysis of Ordinal Categorical Data. John Wiley & Sons, New York1984
        • Gion M.
        • Mione R.
        • Barioli P.
        • et al.
        Percent free prostate-specific antigen in assessing the probability of prostate cancer under optimal analytical conditions.
        Clin Chem. 1998; 44: 2462-2470
        • Marley G.M.
        • Miller M.C.
        • Kattan M.W.
        • et al.
        Free and complexed prostate-specific antigen serum ratios to predict probability of primary prostate cancer and benign prostatic hyperplasia.
        Urology. 1996; 48: 16-22
        • Veltri R.W.
        • Miller M.C.
        Free/total PSA ratio improves differentiation of benign and malignant disease of the prostate.
        Urology. 1999; 53: 736-745
        • Carlson G.D.
        • Calvanese C.B.
        • Partin A.W.
        An algorithm combining age, total prostate-specific antigen (PSA), and percent free PSA to predict prostate cancer.
        Urology. 1998; 52: 455-461
        • Catalona W.J.
        • Partin A.W.
        • Slawin K.M.
        • et al.
        Use of the percentage of free prostate-specific antigen to enhance differentiation of prostate cancer from benign prostatic disease.
        JAMA. 1998; 279: 1542-1547
        • Littrup P.J.
        • Goodman A.C.
        Economic considerations of prostate cancer.
        Cancer. 1995; 75: 1987-1993