Recker F, Kwiatkowski M K, Piironen T, Pettersson K, Goepel M, Tscholl R
Clinic of Urology, Kantonsspital Aarau, Switzerland.
Br J Urol. 1998 Apr;81(4):532-8. doi: 10.1046/j.1464-410x.1998.00616.x.
To investigate the clinical significance of the free-to-total prostate-specific antigen (PSA) ratio in improving the specificity of PSA measurement for detecting prostate cancer within the diagnostic intermediate range (4-10 ng/mL total PSA) in patients referred for the treatment of urinary symptoms.
Serum samples were obtained from 333 consecutive patients with obstructive and irritative urinary symptoms. Of these men, 114 had total PSA levels of 4-10 ng/mL; 22 had prostate cancer (group 1) and 71 had benign prostatic hyperplasia (BPH, group 2). Group 3 consisted of 21 patients with BPH and a chronic indwelling catheter. The concentrations of free and total PSA (ProStatus, Wallac Oy, Turku, Finland) and PSA complexed to alpha-1-antichymotrypsin were measured and the free-to-total PSA ratio calculated. All patients under 70 years of age or with suspicious findings on digital rectal examination or transrectal ultrasonography underwent ultrasound-guided sextant prostate biopsies. Of the 114 patients, 105 (92%) underwent transurethral resection of the prostate and six (5%) radical retropubic prostatectomy.
Patients in group 1 had significantly lower median free PSA concentrations (0.78 ng/mL vs 1.13 ng/mL, P < 0.001) and a lower free-to-total PSA ratio (12.1% vs 19.9%, P < 0.001) than those in group 2. The differences were similar between group 1 and group 3 (median free PSA in group 3, 1.06 ng/mL, P = 0.03, and free-to-total PSA ratio 18.7%, P = 0.007). There were no significant differences between patients in groups 2 and 3. The free-to-total PSA ratio had a higher specificity than total PSA at all sensitivity levels, e.g. a threshold free-to-total PSA ratio of 0.20 detected 91% of cancers and spared 48% (group 2) or 46% (group 3) from unnecessary biopsies. The area under the receiver operating characteristic curve for group 1 vs group 2 was 0.56 (total PSA) and 0.78 (free-to-total PSA ratio) and for group 1 vs group 3 was 0.56 (total PSA) and 0.81 (free-to-total PSA ratio).
In those patients with extensive symptoms from BPH and requiring surgical treatment, the free-to-total PSA ratio improves the specificity for detecting prostate cancer in the diagnostic 'grey zone' of 4-10 ng/mL total PSA. This improvement occurred in patients with or without a chronic indwelling catheter for urinary retention.
探讨游离前列腺特异性抗原（PSA）与总PSA比值在提高PSA检测特异性方面的临床意义，该检测用于在因泌尿系统症状就诊的患者中，在诊断中间范围（总PSA为4 - 10 ng/mL）内检测前列腺癌。
收集333例连续性梗阻性和刺激性泌尿系统症状患者的血清样本。其中，114例患者总PSA水平为4 - 10 ng/mL；22例患有前列腺癌（第1组），71例患有良性前列腺增生（BPH，第2组）。第3组由21例患有BPH且有慢性留置导尿管的患者组成。测量游离PSA和总PSA（ProStatus，Wallac Oy，图尔库，芬兰）以及与α-1-抗糜蛋白酶结合的PSA浓度，并计算游离PSA与总PSA比值。所有70岁以下或直肠指检或经直肠超声检查有可疑发现的患者均接受超声引导下前列腺六分法活检。在这114例患者中，105例（92%）接受了经尿道前列腺切除术，6例（5%）接受了根治性耻骨后前列腺切除术。
第1组患者的中位游离PSA浓度显著低于第2组（0.78 ng/mL对1.13 ng/mL，P < 0.001），游离PSA与总PSA比值也更低（12.1%对19.9%，P < 0.001）。第1组和第3组之间的差异相似（第3组中位游离PSA为1.06 ng/mL，P = 0.03，游离PSA与总PSA比值为18.7%，P = 0.007）。第2组和第3组患者之间无显著差异。在所有灵敏度水平下，游离PSA与总PSA比值的特异性均高于总PSA，例如，游离PSA与总PSA比值阈值为0.20时，可检测出91%的癌症，使第2组（48%）或第3组（46%）避免不必要的活检。第1组与第2组比较的受试者操作特征曲线下面积，总PSA为0.56，游离PSA与总PSA比值为0.78；第1组与第3组比较时，总PSA为0.56，游离PSA与总PSA比值为0.81。
在那些有严重BPH症状且需要手术治疗的患者中，游离PSA与总PSA比值提高了在总PSA为4 - 10 ng/mL的诊断“灰色地带”检测前列腺癌的特异性。无论患者有无因尿潴留而留置慢性导尿管，均出现这种特异性的提高。
