PSA及其相关参数在前列腺癌骨转移中的预测作用

Prediction of bone metastasis in prostate cancer by prostate-specific antigen and PSA-based parameters

目的探讨PSA及其相关参数(F/T、PSAD)在前列腺癌骨转移中的预测作用;方法回顾我院2002年5月￣2005年3月收治的前列腺癌病例,对其中PSA及其相关参数资料完整的87例进行分析,分析这些指标参数与前列腺癌骨转移的相关性和对骨转移的诊断价值,并用ECT和MRI进行验证;结果按PSA<l0μg/L、10￣50μg/L和PSA>50μg/L对前列腺癌患者进行分层,PSA及PSAD与前列腺癌骨转移成正相关(分别为r=0.45038,P<0.0028和r=0.64158,P<0.0001),而F/T则没有相关性。根据上述结果,再以PSA>50μg/L和PSAD>0.4为界分别用PSA、PSAD和PSAD联合PSA对前列腺癌骨转移进行诊断分析,结果发现PSAD+PSA联合诊断应用后,诊断的敏感度、阴性预测值明显提高,对诊断有明显帮助。结论PSAD+PSA联合应用诊断前列腺癌骨转移,是对传统ECT和MRI诊断前列腺癌骨转移的重要补充,对ECT和MRI所带来射线损害的降低和经济负担的减少有重要意义。

Objective To compare PSAD （PSA density）, PSA, free-to total PSA （F/T PSA） ratio used in the prediction of bone metastasis in Chinese prostatic cancer. Methods A total of 87 patients with histologically diagnosed prostate cancer were treated in our hospital from May 2002 to April 2005. Serum PSA levels were measured using a PROSTATUSTM PSA Free/ Total DELFIA kit automatic immunoassay. Prostate volume was estimated by both abdominal and transrectal ultrasound measurements using the prostate ellipse formula （0.52xlength xwidthxheight）. PSAD （PSA/vohime） was calculated by dividing serum PSA level by prostate volume. ECT and MRI were used for detection of bone metastasis. Results Three groups were stratified by PSA level （〈10 μg/L, 10-50 μg/L and 〉50 μg/L）, the correlations were shown between bone metastasis and PSA or PSAD （r=0.45038, p=0.0028 and r=0.64158, p=0.0001 respectively）, but not with F/T PSA. With PSAD cutoff of 0.4, the correlation was also shown （r=0.60761, p=0.0006）. A sensitivity, a specificity, a positive predictive value and a negative predictive value of PSAD cut-off of 0.4 were 84.44%, 50.00%, 64.41% and 89.47%. A sensitivity, a specificity, a positive predictive value and a negative predictive value of PSA cut-off of 50 μg/L were 70.83%, 64.00%, 79.07% and 21.92%. PSAD cut-off of 0.4 combined with PSA cut-off of 50μg/L were showed the highest sum of sensitivity and negative predictive value, which gave a sensitivity of 95.45%, a specificity of 39.53%, a positive predictive value of 61.76% and a negative predictive value of 89.47%. Conclusion Although further studies are needed to determine optimal cut-off value to be used in clinical practice, PSAD cut-off of 0.4 combined with PSA cut-off of 50 μ g/L seems to be useful for the prediction of bone metastasis in chinese prostate cancer patients. This would justify its utility in clinical practice reducing unnecessary ECT and MRI examinations, which are relatively expensive for Chinese patients.