Reiter W
Institut für Klinische Chemie, Klinikum Grosshadern, Ludwig-Maximilians-Universität München, Germany.
Anticancer Res. 1999 Nov-Dec;19(6C):5559-62.
This study examined the clinical relevance of the determination of free PSA (f-PSA) in addition to total PSA (t-PSA) in 6 study groups.
Both total PSA- and free PSA-values of sera samples obtained pretherapeutically from 455 patients with carcinoma (PCA) and 680 patients with benign hyperplasia of the prostate (BPH) were analyzed by means of Enzymun-Test PSA and Enzymun-Test Free PSA (Boehringer Mannheim GmbH, Germany).
At 95% specificity (true negative test results), a cutoff value of 13.6 [micrograms/L] was obtained for total PSA (34 patients with BPH [5%] were above this value). For this cutoff value we calculated a sensitivity (true positive test results) of 44%. Using the same criteria for the ratio Q = f-PSA:t-PSA a cutoff of 0.13 was found again at a specificity of 95%. In a second step only patients with total PSA values below the cutoff level of 13.6 [micrograms/L]) were considered. Out of these patients 26 of 646 with BPH and 108 of 257 with PCA were below the above mentioned ratio (Q = 0.13). Considering both steps (total PSA and Q) 306 patients with PCA were detected correctly and 60 patients with BPH would have been biopsied unnecessarily.
High total PSA levels are a very good indicator for the presence of prostate cancer. There is still concern to improve the differentiation of the diagnosis between BPH and PCA, when an intermediate or low value (< or = 95% specificity) is observed. The determination of the ratio is only useful in this range. It is more powerful at discriminating between PCA and BPH than t-PSA alone and may contribute to a reduction in unnecessary invasive techniques.
本研究在6个研究组中检测了除总前列腺特异抗原（t-PSA）外，游离前列腺特异抗原（f-PSA）测定的临床相关性。
采用酶免疫法检测前列腺特异抗原（Enzymun-Test PSA）和游离前列腺特异抗原（Enzymun-Test Free PSA，德国宝灵曼公司），分析455例前列腺癌（PCA）患者和680例前列腺良性增生（BPH）患者治疗前血清样本的总PSA值和f-PSA值。
总PSA的特异性为95%（真阴性检测结果）时，临界值为13.6[μg/L]（680例BPH患者中有34例[5%]高于此值）。此临界值下的敏感性（真阳性检测结果）为44%。以相同标准计算游离前列腺特异抗原与总前列腺特异抗原比值（Q=f-PSA:t-PSA），特异性为95%时临界值为0.13。第二步仅考虑总PSA值低于13.6[μg/L]临界值的患者。其中，646例BPH患者中有26例、257例PCA患者中有108例低于上述比值（Q=0.13）。综合两个步骤（总PSA和Q），正确检测出306例PCA患者，60例BPH患者将接受不必要的活检。
总PSA水平升高是前列腺癌存在的良好指标。当观察到中间值或低值（≤95%特异性）时，仍需关注改善BPH和PCA诊断的鉴别。比值测定仅在此范围内有用。与单独检测t-PSA相比，其在鉴别PCA和BPH方面更有效，可能有助于减少不必要的侵入性检查。
