Trinkler F B, Schmid D M, Hauri D, Pei P, Maly F E, Sulser T
Department of Urology and Institute for Clinical Chemistry, University Hospital Zurich, Switzerland.
Urology. 1998 Sep;52(3):479-86. doi: 10.1016/s0090-4295(98)00157-5.
To evaluate the ability of free/total prostate-specific antigen (PSA) ratio to improve specificity of prostate cancer detection, compare Diagnostic Products Corporation (DPC) Immulite and Ciba Corning ACS 180 total (t)PSA assay, and define an assay-specific cutoff point and reflex range for DPC PSA ratio (PSAR).
In a prospective study, 206 men were enrolled with measurement of both assays. Group 1 consisted of 173 men with a suspicion of prostate cancer (PCA). Thirteen men with known PCA (group 2) and 20 men younger than 32 years (group 3) were used as control groups.
Our results in group 1 (115 with benign prostatic hyperplasia [BPH], 58 with PCA) revealed a sensitivity of 82.7%, a specificity of 45.2%, and an accuracy of 57.8% for the DPC tPSA assay (cutoff point more than 4.0 ng/mL) within the entire PSA range. tPSA values of the ACS 180 assay were 1.97-fold higher. Within the tPSA gray zone of 2.5 to 10 ng/mL (66 BPH, 23 PCA), specificity and accuracy of DPC tPSA can be improved by using the DPC PSAR (cutoff point less than 19%) from 33.3% to 71.2% and 42.7% to 70.8%, respectively, maintaining the same sensitivity level of 69.6%.
By combining tPSA testing with PSAR within the gray zone, 39.7% (25 of 63) of unnecessary biopsies can be saved, without missing any additional cancers compared with tPSA testing alone. The optimal reflex range for DPC PSAR is 2.5 to 10 ng/mL and the best PSAR cutoff point for biopsy criterion is less than 19% in our high-risk population, with a cancer yield of 34%. Because we still do not have an international PSA standard, it is important to use assay-specific "normal values" and PSAR cutoff points.
评估游离/总前列腺特异性抗原（PSA）比值提高前列腺癌检测特异性的能力，比较诊断产品公司（DPC）Immulite和汽巴康宁ACS 180总（t）PSA检测方法，并确定DPC PSA比值（PSAR）的检测方法特异性临界值和复检范围。
在一项前瞻性研究中，招募了206名男性进行两种检测方法的测量。第1组由173名疑似前列腺癌（PCA）的男性组成。13名已知PCA的男性（第2组）和20名32岁以下的男性（第3组）用作对照组。
我们在第1组（115例良性前列腺增生[BPH]，58例PCA）中的结果显示，在整个PSA范围内，DPC tPSA检测方法（临界值大于4.0 ng/mL）的敏感性为82.7%，特异性为45.2%，准确性为57.8%。ACS 180检测方法的tPSA值高1.97倍。在2.5至10 ng/mL的tPSA灰色区域内（66例BPH，23例PCA），使用DPC PSAR（临界值小于19%）可将DPC tPSA的特异性和准确性分别从33.3%提高到71.2%，从42.7%提高到70.8%，同时保持69.6%的相同敏感性水平。
通过在灰色区域内将tPSA检测与PSAR相结合，与单独的tPSA检测相比，可以避免39.7%（63例中的25例）不必要的活检，且不会遗漏任何额外的癌症。在我们的高危人群中，DPC PSAR的最佳复检范围是2.5至10 ng/mL，活检标准的最佳PSAR临界值小于19%，癌症检出率为34%。由于我们仍然没有国际PSA标准，使用检测方法特异性的“正常值”和PSAR临界值很重要。
