Sela Ben-Ami, Doolman Ram
lnstitute of Chemical Pathology, Sheba Medical Center, Tel Hashomer.
Harefuah. 2011 May;150(5):466-9, 489.
Since its introduction as a mass-screen parameter for early detection of prostate cancer, PSA was credited for a significant revolution in the management of prostate disease. But over 2 decades of global experience with this marker have emphasized that the recommended threshold value of 4.0 ng/ml may not be valid in distinguishing tumor growth from benign proliferation of the prostate in over 30% of the cases. Hence, more advanced tools of PSA evaluation have been introduced such as "PSA velocity", "PSA density" or age-related PSA". Recently, precursor molecules of PSA were identified, which are assumed to be zymogen structures devoid of proteolytic activity. These precursor species known as pro-PSAs possess an additional "tail" ranging in size from 2 to 7 extra amino acids at the N terminus of PSA, and represent a fraction of the non-complex or "free PSA", that has usually been identified as a marker for non-cancerous proliferation of the prostate. Interestingly, one of these proPSA structures in particular, [-2]proPSA, has demonstrated to be more specifically indicative of prostate tumor growth in numerous clinical studies. Lately, a chemiluminescence kit has been approved by the European Health Agency as a more specific marker for diagnosis of prostate malignancy, mostly in men with PSA levels ranging from 2-10 ng/ml.
自从前列腺特异性抗原（PSA）作为前列腺癌早期检测的大规模筛查参数被引入以来，它被认为给前列腺疾病的管理带来了重大变革。但全球20多年来使用该标志物的经验表明，在超过30%的病例中，推荐的4.0 ng/ml阈值可能无法有效区分前列腺肿瘤生长与良性增生。因此，已引入了更先进的PSA评估工具，如“PSA速率”、“PSA密度”或“年龄相关PSA”。最近，PSA的前体分子被鉴定出来，它们被认为是缺乏蛋白水解活性的酶原结构。这些被称为前PSA的前体物质在PSA的N端具有一个额外的“尾巴”，其大小从2到7个额外氨基酸不等，并且代表了非复合或“游离PSA”的一部分，游离PSA通常被认为是前列腺非癌性增生的标志物。有趣的是，在众多临床研究中，这些前PSA结构之一，即[-2]proPSA，已被证明更能特异性地指示前列腺肿瘤生长。最近，一种化学发光试剂盒已被欧洲卫生机构批准为诊断前列腺恶性肿瘤的更特异性标志物，主要用于PSA水平在2 - 10 ng/ml之间的男性。
