Al Saidi Safana S, Al Riyami Nafila B, Al Marhoon Mohammed S, Al Saraf Mohammed S, Al Busaidi Salim S, Bayoumi Riad, Mula-Abed Waad-Allah S
Department of Laboratory Medicine and Pathology, Royal Hospital, Muscat, Oman.
Department of Clinical Biochemistry, Sultan Qaboos University Hospital, Muscat, Oman.
Oman Med J. 2017 Jul;32(4):275-283. doi: 10.5001/omj.2017.55.
Prostate cancer is the leading cancer in older men. The Ministry of Health Oman Cancer Incidence Registry 2013 lists cancer of the prostate as the first most common cancer in males. Therefore, early detection is important and prostate-specific antigen (PSA) is widely used as an established laboratory test. However, despite its wide use, its value in screening, particularly in asymptomatic males, is controversial when considering the risks and benefits of early detection.
This prospective, observational study included 136 males (67.0±8.9 years; range 45-90) who were scheduled for a prostate biopsy in two different tertiary care teaching hospitals in Oman: the Royal Hospital and Sultan Qaboos University Hospital. Blood specimens from these patients were collected at the same setting before obtaining a prostatic biopsy. Three PSA markers (total PSA (tPSA), free PSA (fPSA), and [-2]proPSA (p2PSA)) were measured and the Prostate Health Index (phi) calculated. The histopathological report of the prostatic biopsy for each patient was obtained from the histopathology laboratory of the concerned hospital along with clinical and laboratory data through the hospital information system.
Phi has the highest validity markers compared with other prostate markers, with a sensitivity of 82.1%, specificity of 80.6%, and area under the curve (AUC) value of 0.81 at a cutoff of 41.9. The other prostatic markers showed sensitivities and specificities of 78.6% and 25.9% for tPSA; 35.7% and 92.6% for %fPSA; and 64.3% and 82.4% for %p2PSA, respectively. The AUCs at the best cutoff values were 0.67 at 10.1 µg/L for tPSA; 0.70 at 11.6% for %fPSA; and 0.55 at 1.4% for %p2PSA. An association between phi values and aggressiveness of prostate malignancy was noted. Of the 28 patients with prostate cancer, 22 patients had tPSA > 4 µg/L. However, no patient had phi in the low-risk category, and five, six, and 17 patients had phi in the moderate-, high-, and very high-risk categories, respectively.
Phi outperforms tPSA and fPSA when used alone or in combination, and appears to be more accurate than both markers in excluding prostate cancer before biopsy. Use of this biomarker helps clinicians to avoid unnecessary biopsies, particularly in patients with gray-zone tPSA level. Phi is the strongest marker that correlates proportionally with Gleason Score; therefore, it is also useful in predicting the aggressiveness of the disease. This is the first reported experience for the use of p2PSA and phi in Oman, the Middle East, and North Africa.
前列腺癌是老年男性中最常见的癌症。阿曼卫生部2013年癌症发病率登记处将前列腺癌列为男性中最常见的癌症。因此，早期检测很重要，前列腺特异性抗原（PSA）被广泛用作一项既定的实验室检测。然而，尽管其应用广泛，但在考虑早期检测的风险和益处时，其在筛查中的价值，尤其是在无症状男性中的价值仍存在争议。
这项前瞻性观察性研究纳入了136名男性（67.0±8.9岁；年龄范围45 - 90岁），他们在阿曼的两家不同的三级医疗教学医院——皇家医院和苏丹卡布斯大学医院接受前列腺活检。在进行前列腺活检前，于相同环境下采集这些患者的血液标本。检测三种PSA标志物（总PSA（tPSA）、游离PSA（fPSA）和[-2]前列腺特异性抗原（p2PSA）），并计算前列腺健康指数（phi）。通过医院信息系统从相关医院的组织病理学实验室获取每位患者前列腺活检的组织病理学报告以及临床和实验室数据。
与其他前列腺标志物相比，phi具有最高的有效性标志物，在临界值为41.9时，敏感性为82.1%，特异性为80.6%，曲线下面积（AUC）值为0.81。其他前列腺标志物显示，tPSA的敏感性和特异性分别为78.6%和25.9%；%fPSA的敏感性和特异性分别为35.7%和92.6%；%p2PSA的敏感性和特异性分别为64.3%和82.4%。tPSA在最佳临界值10.1μg/L时的AUC为0.67；%fPSA在11.6%时的AUC为0.70；%p2PSA在1.4%时的AUC为0.55。注意到phi值与前列腺恶性肿瘤的侵袭性之间存在关联。在28例前列腺癌患者中，22例患者的tPSA>4μg/L。然而，没有患者的phi处于低风险类别，分别有5例、6例和17例患者的phi处于中、高和非常高风险类别。
单独使用或联合使用时，phi均优于tPSA和fPSA，并且在活检前排除前列腺癌方面似乎比这两种标志物都更准确。使用这种生物标志物有助于临床医生避免不必要的活检，尤其是在tPSA处于灰色区域水平的患者中。phi是与Gleason评分成比例相关的最强标志物；因此，它在预测疾病的侵袭性方面也很有用。这是在阿曼、中东和北非首次报道使用p2PSA和phi的经验。
