Benecchi Luigi
Division of Urology, Fidenza Hospital, Parma, Italy.
Arch Ital Urol Androl. 2006 Jun;78(2):44-8.
Aim of this study was to evaluate different decision strategies based on variations in the cut-off value of percent free PSA and in the range of total PSA values (reflex range) in which free PSA testing was applied. We compared these strategies to conventional total PSA testing by determining which strategies would provide a maximum decrease in unnecessary biopsies with a minimum number of additional undetected cancers.
This retrospective study was conducted with 807 patients who were referred to transrectal ultrasound biopsies for elevated serum PSA levels or for abnormal digital rectal examination. Overall 156 patients were affected by primary prostate cancer (CaP), 651 were controls without prostate cancer (benign prostatic hypertrophy, prostatic intraepithelial neoplasm, prostatitis or normal prostatic gland).
Total PSA was significantly higher (F=4.93; p<0.0001) and percent free PSA was significantly lower in cancer patients than in controls (F=2.16; p<0.0001). Sensitivity, specificity and the positive likelihood ratio (LR+) of PSA and percent free PSA have been calculated for several total PSA intervals: PSA 4-10 ng/ml, 3-10 ng/ml, 3-20 ng/ml, 2-10 ng/ml, 2-20 ng/ml. These data suggest that in the reflex range 2-10 ng/ml there are the best results. On ROC comparison restricted to men with total PSA between 2 and 10 ng/ml, percent free PSA also had a higher area under the curve than total PSA (AUC 0.7452 for free percent PSA; 0.6267 for total PSA: p = 0.0059).
The PSA revolution that occurred over the previous 2 decades has positively impacted the detection of prostate cancer. Percent free PSA improves specificity, at the beginning the percent free PSA was used only in the gray zone 4-10 ng/ml. Analyzing our data, we confirm that the usefulness of percent free PSA in prostate cancer diagnosis increases, enlarging the reflex range. Our best result is obtained in the reflex range 2-10 ng/ml using a percent free PSA cut-off of 22%.
本研究旨在评估基于游离前列腺特异抗原（free PSA）百分比临界值变化以及应用游离PSA检测的总前列腺特异抗原（total PSA）值范围（反射范围）的不同决策策略。我们通过确定哪些策略能在额外未检测到的癌症数量最少的情况下最大程度减少不必要的活检，将这些策略与传统的总PSA检测进行比较。
本回顾性研究纳入了807例因血清PSA水平升高或直肠指检异常而接受经直肠超声活检的患者。共有156例患者患有原发性前列腺癌（CaP），651例为无前列腺癌的对照组（良性前列腺增生、前列腺上皮内瘤变、前列腺炎或正常前列腺）。
癌症患者的总PSA显著更高（F = 4.93；p < 0.0001），游离PSA百分比显著低于对照组（F = 2.16；p < 0.0001）。已针对几个总PSA区间计算了PSA和游离PSA百分比的敏感性、特异性及阳性似然比（LR +）：PSA 4 - 10 ng/ml、3 - 10 ng/ml、3 - 20 ng/ml、2 - 10 ng/ml、2 - 20 ng/ml。这些数据表明，在2 - 10 ng/ml的反射范围内结果最佳。在仅针对总PSA在2至10 ng/ml之间的男性进行的ROC比较中，游离PSA百分比的曲线下面积也高于总PSA（游离PSA百分比的AUC为0.7452；总PSA的AUC为0.6267：p = 0.0059）。
过去20年发生的PSA革命对前列腺癌的检测产生了积极影响。游离PSA百分比提高了特异性，起初游离PSA百分比仅用于4 - 10 ng/ml的灰色区域。通过分析我们的数据，我们证实随着反射范围扩大，游离PSA百分比在前列腺癌诊断中的有用性增加。使用22%的游离PSA百分比临界值，在2 - 10 ng/ml的反射范围内可获得最佳结果。
