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Objective: Percent free prostate-specific antigen (PSA) is a promising tool for prostate cancer (CaP) diagnosis. However, its diagnostic performances have not yet been established. The present study was carried out with the aim of evaluating percent free PSA in the most favourable analytical conditions., Materials and Methods: Eighty-eight patients affected by newly diagnosed, untreated, primary CaP, and 169 cases with biopsy-confirmed, untreated, benign prostatic hypertrophy (BPH) were prospectively enrolled. Abbott AxSYM total and free PSA were measured by the same technician using the same instrument and the same reagent batch., Results: Percent free PSA was more effective than total PSA in differential diagnosis between CaP and BPH in every evaluated dose range of total PSA. In cases with total PSA >4 microg/l, percent free PSA could have reduced by about 50% the rate of unnecessary biopsies with a probably still acceptable 93% cancer detection rate. The likelihood of CaP after the determination of percent free PSA was in fact higher than 50% using cut-off points which provide low sensitivity values (i.e. 58% in men aged 50-59 years)., Conclusions: Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 microg/l and in reducing the rate of unnecessary biopsies in men with total PSA higher than 4 microg/l. However, percent free PSA should be cautiously interpreted in decision making in individual patients since post-test probability is relatively low in men aged 50-70 years.

Although general consensus exists that percent free prostate-specific antigen (PSA) is superior to total immunoreactive PSA for prostate cancer (CaP) detection, its diagnostic performance is not yet well established. Analytical problems may account for difficulties in evaluating percent free PSA because the free PSA concentration is substantially lower than that of total PSA. The aim of the present study was to establish the diagnostic performances of the IMMULITE percent free PSA assay from Diagnostics Products Corp. under experimental conditions optimized to minimize analytical variability. Eighty-five patients with untreated primary CaP and 261 with untreated benign prostate hypertrophy (BPH) were prospectively enrolled. The Diagnostics Products IMMULITE total (Third Generation) and free PSA were measured by the same technician, using the same instrument and the same reagent batch. We calculated the post-test probability to express how the likelihood of the diagnosis of CaP changed after the percent free PSA was determined. Areas under the ROC curves of percent free PSA were better than those of total PSA in every evaluated range of total PSA. The percent free PSA could have reduced the rate of unnecessary biopsies by 47% in patients with total PSA >/=4 microg/L with only 3.8% false-negative results. The post-test probability of percent free PSA was, however, <50% in men 50-70 years of age, using cutoff points providing sensitivity from 99% to 80%. Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 microg/L. In men with low total PSA, the diagnostic performance of the percent free PSA assay may be optimized by controlling methodological variability. The percent free PSA assay is effective in reducing the rate of unnecessary biopsies in men with total PSA >4 microg/L. However, the post-test probability provided by percent free PSA is relatively low in asymptomatic patients 50-70 years of age.

Unlabelled: The percent free PSA value is a promising diagnostic tool for prostate cancer. However, its actual role has not yet been established because of the widely diverging sensitivity and specificity values. This could depend at least in part on analytical difficulties, since the free PSA concentration is much lower than that of total PSA. The present investigation was designed to evaluate the diagnostic performance of the percent free PSA in the most favorable analytical conditions., Materials and Methods: 81 patients affected by newly diagnosed, untreated primary prostate cancer (CaP) and 239 patients with untreated benign prostatic hyperplasia (BPH) were prospectively enrolled. Hybritech total and free PSA were measured by the same technician using the same reagent batch., Results: The percent free PSA was not significantly associated with age, tumor stage, gland volume, Gleason score, and total PSA, nor was it significantly affected by concomitant prostatic complications either in CaP or BPH. Percent free PSA was more effective than total PSA in the differential diagnosis between CaP and BPH in every evaluated dose range of total PSA. Percent free PSA determination could have reduced the rate of unnecessary biopsies in cases with total PSA > or = 4 ng/mL and > or = 10 ng/mL (avoided biopsies 61% and 63%, respectively). The post-test probability of the disease, which represents the proportion of patients with a positive percent free PSA value who have the disease, was, however, relatively low in younger patients with total PSA within the normal range., Conclusions: The diagnostic performance of the percent free PSA value is enhanced when the methodological variability is reduced, particularly in men with low total PSA. Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 ng/mL. The percent free PSA value is effective in reducing the rate of unnecessary biopsies in men with total PSA higher than 4 or 10 ng/mL. However, due to its relatively low post-test probability, the percent free PSA value should be interpreted with caution in the decision-making related to individual patients and should be used in association with clinical and instrumental evaluation of the patient.