Pannek J, Rittenhouse H G, Chan D W, Epstein J I, Walsh P C, Partin A W
James Buchanan Brady Urological Institute, Department of Pathology, The Johns Hopkins Medical Institution, Baltimore, Maryland, USA.
J Urol. 1998 Apr;159(4):1238-42.
The free-to-total serum prostate specific antigen (PSA) ratio (percent free PSA) has been demonstrated to have clinical use for early detection of men with prostate cancer with total PSA levels between 4.0 and 10.0 ng./ml. Several studies evaluating the usefulness of percent free PSA for the staging of clinically localized prostate cancer have provided conflicting results. We further investigate the usefulness of percent free PSA for staging of clinically localized prostate cancer.
In 263 men with clinically localized prostate cancer who underwent radical prostatectomy total PSA and free PSA were measured preoperatively. Pathological stages were classified as organ confined in 134 cases, capsular penetration in 92, seminal vesicle involvement in 7, involvement of the surgical margins in 20 and lymph node involvement in 10.
Percent free PSA was significantly different between men with organ confined versus nonorgan confined tumors (p <0.0001) and between those with favorable versus unfavorable pathology (p <0.0001). A cutoff of 12% free PSA provided a 72% positive predictive value and 52% negative predictive value for favorable pathology. A cutoff of 15% free PSA provided a 76% and 53% positive and negative predictive value, respectively, for organ confined disease.
These data demonstrate that the use of percent free PSA may be of additional value for the staging of clinically localized prostate cancer. The recommendations for cutoff levels of percent free PSA for detection and staging of localized prostate cancer are preliminary and can only be given for this particular assay. A large multicenter trial, controlling for age, stage and grade distribution, as well as for a uniform pathological evaluation and comparable total and free PSA assays, is required to elucidate this issue further.
血清游离前列腺特异性抗原（PSA）与总PSA的比值（游离PSA百分比）已被证明在早期检测总PSA水平介于4.0至10.0 ng/ml之间的前列腺癌男性患者中具有临床应用价值。多项评估游离PSA百分比对临床局限性前列腺癌分期有用性的研究得出了相互矛盾的结果。我们进一步研究游离PSA百分比对临床局限性前列腺癌分期的有用性。
对263例接受根治性前列腺切除术的临床局限性前列腺癌男性患者术前测定总PSA和游离PSA。病理分期分为134例器官局限型、92例包膜侵犯型、7例精囊受累型、20例手术切缘受累型和10例淋巴结受累型。
器官局限型肿瘤患者与非器官局限型肿瘤患者之间以及病理结果良好与不良的患者之间，游离PSA百分比存在显著差异（p<0.0001）。游离PSA百分比为12%时，对病理结果良好的阳性预测值为72%，阴性预测值为52%。游离PSA百分比为15%时，对器官局限型疾病的阳性预测值和阴性预测值分别为76%和53%。
这些数据表明游离PSA百分比的应用可能对临床局限性前列腺癌的分期具有额外价值。关于游离PSA百分比用于局限性前列腺癌检测和分期的临界值水平的建议是初步的，且仅适用于该特定检测方法。需要进行一项大型多中心试验，控制年龄、分期和分级分布，以及进行统一的病理评估和可比的总PSA及游离PSA检测，以进一步阐明这一问题。
