Reiter W, Stieber P, Schmeller N, Nagel D, Hofmann K, Fateh-Moghadam A
Institut für Klinische Chemie, Klinikum Grosshadern, Ludwig-Maximilians-Universität München, Germany.
Anticancer Res. 1997 Nov-Dec;17(6D):4759-65.
We studied the methodical and clinical relevance of five determination assays for free PSA (f-PSA) in addition to the corresponding total PSA antigen (t-PSA).
Both the total PSA- and free-PSA-values of frozen sera obtained pretherapeutically from 80 patients with carcinoma (PC) and 171 patients with benign hyperplasia of the prostate (BPH) were analysed by means of Enzymun-Test PSA/BM, PSA-RIACT/ CIS, CanAg PSA EIA/ Dia, Tandem-E PSA/Hyb, PSA IRMA/ IBL and Enzymun-Test PSA free/BM, F PSA-RIACT/CIS, CanAg Anti Free PSA/Dia, Tandem-R free PSA/Hyb, FREE PSA IRMA/IBL.
The coefficient of correlation between Hybritech PSA assay and the other assays was determined in patients with benign and malignant prostatic diseases. There was a strong overall correlation with all assays measuring total or free PSA, respectively. A satisfying correlation is also shown using a limited scale up to 50 ng/mL for total PSA and 5 ng/mL for free PSA. At 95% specificity sensitivities of total PSA between 40% and 50% of the ratio (Q) = free PSA/total PSA between 4% and 28% were calculated. In a second step only patients with total PSA values below the cutoff level of 16.5 [micrograms/l] (BM), 13.9 [micrograms/l] (CIS), 14.7 [micrograms/l] (Dia), 15.7 [micrograms/l] (Hyb) and 16.8 [micrograms/l] (IBL) were considered. Using the BM assays, of these patients 9 of 162 with BPH and 14 of 47 with PC [CIS: 14 of 162 with BPH and 4 of 48 with PC/Dia: 13 of 162 with BPH and 11 of 48 with PC/Hyb: 6 of 156 with BPH (missing values = 6) and 11 of 40 with PC/IBL: 11 of 160 with BPH (missing values = 1) and 13 of 33 with PC (missing values = 2)] were below the ratio Q = free PSA/total PSA. Considering both steps (total PSA and Q) using the BM assay 47 patlents with PC were detected correctly and 18 patients with BPH would have been biopsied unnecessarily (positive biopsy rate = pos. br.: 72%) [CIS: 38 patients with PC and 23 patients with BPH (pos. br.: 62%)/Dia: 43 patients with PC and 22 patients with BPH (pos. br.: 66%)/Hyb: 51 patients with PC and 15 patients with BPH (pos. br.: 77%)/IBL: 46 patients with PC and 20 patients with BPH (pos. br.: 70%)]
High total PSA levels of all assays are a very good indicator for the presence of prostate cancer. There is still concern to improve the differentiation between BPH and PC, when an intermediate or low value (< 95% specificity) is observed. The determination of Q is only useful in this range and it might be helpful for the clinicians decision to apply or avoid biopsy.
除了相应的总PSA抗原（t-PSA）外，我们还研究了五种游离PSA（f-PSA）测定方法的方法学和临床相关性。
通过酶免疫试验PSA/BM、PSA-RIACT/CIS、CanAg PSA EIA/Dia、Tandem-E PSA/Hyb、PSA IRMA/IBL以及酶免疫试验游离PSA/BM、F PSA-RIACT/CIS、CanAg抗游离PSA/Dia、Tandem-R游离PSA/Hyb、游离PSA IRMA/IBL，分析了80例前列腺癌（PC）患者和171例前列腺良性增生（BPH）患者治疗前获得的冷冻血清的总PSA值和游离PSA值。
在前列腺良性和恶性疾病患者中测定了Hybritech PSA测定法与其他测定法之间的相关系数。分别与所有测量总PSA或游离PSA的测定法存在很强的总体相关性。对于总PSA在高达50 ng/mL以及游离PSA在高达5 ng/mL的有限范围内，也显示出令人满意的相关性。在95%特异性下，计算出总PSA的敏感性在40%至50%之间，游离PSA/总PSA的比值（Q）在4%至28%之间。第二步仅考虑总PSA值低于16.5[微克/升]（BM）、13.9[微克/升]（CIS）、14.7[微克/升]（Dia）、15.7[微克/升]（Hyb）和16.8[微克/升]（IBL）临界值的患者。使用BM测定法，在这些患者中，162例BPH患者中有9例以及47例PC患者中有14例[CIS：162例BPH患者中有14例以及48例PC患者中有4例/Dia：162例BPH患者中有13例以及48例PC患者中有11例/Hyb：156例BPH患者中有6例（缺失值=6）以及40例PC患者中有11例/IBL：160例BPH患者中有11例（缺失值=1）以及33例PC患者中有13例（缺失值=2）]游离PSA/总PSA比值低于Q。考虑两个步骤（总PSA和Q），使用BM测定法正确检测出47例PC患者，18例BPH患者将接受不必要的活检（阳性活检率=pos.br.：72%）[CIS：38例PC患者和23例BPH患者（pos.br.：62%）/Dia：43例PC患者和22例BPH患者（pos.br.：66%）/Hyb：51例PC患者和15例BPH患者（pos.br.：77%）/IBL：46例PC患者和20例BPH患者（pos.br.：70%）]
所有测定法中总PSA水平高是前列腺癌存在的一个很好指标。当观察到中间值或低值（<95%特异性）时，仍需关注改善BPH和PC之间的鉴别。Q的测定仅在此范围内有用，可能有助于临床医生决定是否进行活检。
