Objective To evaluate the value of prostate specific antigen (PSA)-related parameters in the differential diagnosis between asymptomatic inflammatory prostatitis (AIP) and prostate cancer in middle-aged and elderly patients with serum level of total PSA (tPSA) of 4-20 μg/L. Methods In total, 1 290 male patients with serum tPSA within the range from 4 to 20 μg/L, undergoing prostate puncture biopsy and with complete transrectal ultrasound data were recruited in this investigation. Subsequently, 152 patients aged ≥ 40 years and diagnosed with AIP or prostate cancer were selected. The tPSA, the ratio of tPSA to free PSA (fPSA) (f/t), PSA density (PSAD), transition zone PSA density (TZPSAD) and peripheral zone PSA density (PZPSAD) were statistically compared between two groups. The findings of prostate puncture biopsy were used as the gold standard. The receiver operator characteristic (ROC) curves of PSA-related parameters with statistical significance were delineated and the optimal diagnostic threshold at the maximal Youden index was calculated to assess the value in the differential diagnosis between AIP and prostate cancer. Results Forty-six patients were pathologically diagnosed with AIP and 106 with prostate cancer. The tPSA, f/t and PZPSAD did not significantly differ (all P>0.05), whereas PSAD and TZPSAD significantly differed between AIP and prostate cancer patients with serum tPSA of 4-20 μg/L (both P<0.01). The ROC curves of PSAD and TZPSAD in the differential diagnosis between AIP and prostate cancer did not significantly differ (both P>0.05). The optimal diagnostic thresholds were obtained when PSAD=0.23 μg/(L·cm3)with a sensitivity of 74.5% and specificity of 64.3% or TZPSAD=0.44 μg/(L·cm3)with a sensitivity of 78.3% and specificity of 63.0%. PSAD and TZPSAD could increase the positive diagnostic rate of prostate cancer from 70.0% and 69.7% to 81.4% and 83.0%, and avoid unnecessary prostate puncture biopsy in 60.9% and 63.0% of AIP patients. Conclusions Much attention should be placed to the incidence of AIP in patients suspected with prostate cancer with PSAD<0.23 μg/(L·cm3)or TZPSAD<0.44 μg/(L·cm3)when the serum tPSA within the range from 4 to 20 μg/L. PSAD and TZPSAD can be used to differentially diagnose between AIP and prostate cancer in middle-aged and elderly patients, which not only enhance the positive diagnostic rate of prostate cancer, but also avert unnecessary prostate puncture biopsy for AIP patients.%目的 探讨中老年患者血清总前列腺特异性抗原(tPSA)为4~20 μg/L时,PSA相关指标鉴别无症状性前列腺炎(AIP)和前列腺癌中的诊断效能.方法 收集血清tPSA为4~20 μg/L并行前列腺穿刺活组织检查(活检)、有完整经直肠前列腺B超资料的1 290例男性患者,筛选出年龄≥40岁、经活检诊断为AIP和前列腺癌共152例.比较2组间tPSA、tPSA与游离PSA(fPSA)比值(f/t)、PSA密度(PSAD)、移行区PSA密度(TZPSAD)、外周带PSA密度(PZPSAD)的差异.以前列腺活检结果为金标准,绘制2组间差异有统计学意义的PSA相关指标受试者工作特征(ROC)曲线,计算约登指数最大时的最佳诊断界值,分析其鉴别AIP与前列腺癌的诊断效能.结果 经病理确诊AIP 46例,前列腺癌106例.tPSA为4~20 μg/L的AIP和前列腺癌患者间tPSA、f/t、PZPSAD比较差异均无统计学意义(P均>0.05),2组的PSAD、TZPSAD比较差异均有统计学意义(P均<0.01).PSAD、TZPSAD鉴别AIP与前列腺癌的ROC曲线下面积比较差异无统计学意义(P>0.05);PSAD=0.23 μg/(L·cm3)或TZPSAD=0.44 μg/(L·cm3)为最佳诊断界值,其鉴别诊断前列腺癌的灵敏度、特异度分别为74.5%、64.3%和78.3%、63.0%,可将前列腺癌的阳性诊断率从原来的70.0%和69.7%分别提高至81.4%和83.0%,分别避免60.9%和63.0%的中老年AIP患者行不必要的穿刺活检.结论 tPSA为4~20 μg/L时,对PSAD<0.23 μg/(L·cm3)或TZPSAD<0.44 μg/(L·cm3)的前列腺癌疑似患者需特别注意有无AIP.PSAD、TZPSAD有助于对中老年患者AIP与前列腺癌的鉴别诊断,其不仅可以提高前列腺癌的阳性诊断率,还可减少AIP患者行不必要的前列腺穿刺活检.
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