Dinçel C, Caşkurlu T, Taşçi A I, Cek M, Sevin G, Fazlioğlu A
Department of Urology, Vakif Gureba Education Hospital, Istanbul, Turkey.
Int Urol Nephrol. 1999;31(4):497-509. doi: 10.1023/a:1007167328877.
To improve the specificity and sensitivity of prostatic cancer detection, we prospectively evaluated total prostate specific antigen (PSA) level, PSA density, free-to-total PSA ratio and a new formula called prostate malignancy index (PMI) as a discriminator of prostate cancer in patients with intermediate PSA levels and normal digital rectal examinations.
Between November 1995 and October 1997, 95 patients who had serum PSA levels of 4.0 to 10.0 ng/ml with normal digital rectal examinations were prospectively evaluated. All patients underwent one or two times transrectal ultrasound guided prostate biopsies. Based on age specific reference range of PSA, PSA density and % free PSA ratio, PMI was calculated for each patient. The free and total serum PSA concentrations were determined by an Immulite assay system. (Diagnostic Product Corp., Los Angeles, California).
Overall 20 of 95 (21%) patients had prostate cancer. There were no significant differences in patient mean age and mean total PSA between those with benign and those with malignant biopsies (p>0.05). However, there were significant differences in mean PSAD, mean free-to-total PSA ratio and mean PMI (p<0.01, p<0.05, p<0.01, respectively). Benign condition specificities for PM index, percent free PSA, PSA density and total PSA at a 90% sensitivity for prostate cancer were 48%, 10.6%, 8% and 4%, respectively. Of 95 patients, 27 (28.4%) had a PMI of equal or more than 3.1, including 12 of 75 (16%) with negative biopsy and 15 of 20 (75%) with positive biopsy. Furthermore a cutoff MI 0.86 P correctly identified 24% of benign cases without missing any prostate cancer cases. The comparison of receiver operating characteristic (ROC) curve areas showed that PMI was better than total PSA (p<0.01). Although, the area under the ROC curve of % free PSA and PSAD were higher than the area of total PSA, these differences were not statistically significant (p>0.05).
We concluded that the prostate malignancy index could be utilized to differentiate benign conditions from prostate cancer in patients with intermediate PSA levels and normal digital rectal examination. Also significant numbers of negative biopsies can be prevented in these patients.
为提高前列腺癌检测的特异性和敏感性，我们前瞻性评估了总前列腺特异性抗原（PSA）水平、PSA密度、游离PSA与总PSA比值以及一种名为前列腺恶性指数（PMI）的新公式，以鉴别PSA水平中等且直肠指检正常的患者是否患有前列腺癌。
1995年11月至1997年10月，对95例血清PSA水平为4.0至10.0 ng/ml且直肠指检正常的患者进行了前瞻性评估。所有患者均接受了一或两次经直肠超声引导下的前列腺活检。根据PSA、PSA密度和游离PSA百分比的年龄特异性参考范围，计算每位患者的PMI。血清游离PSA和总PSA浓度通过免疫发光分析系统测定（诊断产品公司，加利福尼亚州洛杉矶）。
95例患者中共有20例（21%）患有前列腺癌。良性活检组和恶性活检组患者的平均年龄和平均总PSA水平无显著差异（p>0.05）。然而，平均PSAD、平均游离PSA与总PSA比值和平均PMI存在显著差异（分别为p<0.01、p<0.05、p<0.01）。前列腺癌敏感度为90%时，PM指数、游离PSA百分比、PSA密度和总PSA的良性疾病特异性分别为48%、10.6%、8%和4%。95例患者中，27例（28.4%）的PMI等于或大于3.1，其中75例活检阴性患者中有12例（16%），20例活检阳性患者中有15例（75%）。此外，截断值MI 0.86 P正确识别了24%的良性病例，且未遗漏任何前列腺癌病例。受试者操作特征（ROC）曲线面积比较显示，PMI优于总PSA（p<0.01）。虽然游离PSA百分比和PSAD的ROC曲线下面积高于总PSA的面积，但这些差异无统计学意义（p>0.05）。
我们得出结论，前列腺恶性指数可用于鉴别PSA水平中等且直肠指检正常的患者的良性疾病和前列腺癌。此外，可防止这些患者中大量出现活检阴性的情况。
