Value Of Combined Use Of MRS, FPSA/tPSA And PSAD In Diagnosing Prostate Cancers At PSA Gray Zone

Objective :The purpose of this study was to explore the value of combined use of MRS, fPSA/tPSA and PSAD in diagnosing of prostate cancer at serum PSA gray zone(4~10 ng/ml) in order to increase the diagnosis accuracy of prostate cancer and avoid unnecessary biopsy.Methods:1. Patients selectionSixty male patients(age >45 years) who come to our hospital to see a doctor for dysuria or PSA abnormal(4~10 ng/ml) during August 2013 to August 2014 were retrospective analyzed.2. Collection of serum samples and calculation of t PSA, fPSA,prostate volume, fPSA/t PSA and PSADSerum samples were collected for PSA determination. External stimulated factors which may affecting serum level of PSA, such as digital rectal examination, prostate B ultrasound, cystoscopy, indwelling catheter and prostatic massage, should be avoided 2 weeks before serum collection. Both t PSA and fPSA were detected by chemiluminescence method. fPSA/t PSA was calculated by fPSA divide t PSA. Based on MRI results, prostate volume was calculated by equation: Prostate volume=Anteroposterior diameter of prostate(cm) × Right-left diameter of prostate(cm) ×Vertical diameter of prostate(cm). PSAD was calculated by tPSA divide prostate volume(cm3).3. MRI and MRS examinationThree days after PSA determination, patient’s prostate was scanned by MRI and MRS using MAGNETOM VERIO 3.0T MRI equipment. Results were introduced into a workstation to analyze the spectroscopic results of Choline(Cho), Creatine(Cre) and Citrate(Cit) of region of interest(ROI), all those three are metabolism products of prostate. MRS was calculated based on equation: MRS=(Cho+Cre)/ Cit. The so called "ROI" included MRI signal abnormal region and peripheral suspected lesion area.4. Collection of pathological specimensAfter completion of PSA determination, MRI and MRS examination, patients were asked to sign written informed consent to undergo ultrasound guided transrectal prostate biopsy or transurethral resection to collect pathological specimens. 12-core systematic biopsy was used(digital rectal examination was performed before surgery, B type ultrasound was used to find nodus, biopsy core was increased in abnormal area of MRI and MRS). For patients undergoing transurethral resection of the prostate, pathological specimens sampling was taken place at postoperative gland specimens focused on those regions significantly different from normal prostate tissue. Pathological specimens were sent to pathology department of our hospital to confirm diagnosis.5. Statistical analysisDemographics and clinical data were analyzed by SPSS 19.0 software using independent-samples t test or Mann-Whitney test depends upon circumstances. Receiver operating characteristic(ROC) curves were drew by Med Calc software and comparison of the area under curve(AUC) was completed by De Long method. Decision curve was drew by Excel. A value of P <0.05 was considered statistically significant.Results1. Pathology results: Pathology results showed that, of those 60 enrolled patients, 24 had prostatic carcinoma( PCa group), other 36 had benign prostatic hyperplasia(BPH group).When compared with BPH group, the age and tPSA of Pca group showed no significant inter-group difference(P > 0.05); While other parameters, such as fPSA, fPSA/tPSA, prostate volume, PSAD and MRS, all showed significant difference(P <0.05).2. Diagnosis performance of MRS, PSAD and fPSA/tPSA: The area under the ROC curves of MRS, PSAD and fPSA/tPSA in diagnosing prostate cancers at PSA gray zone were 0.712, 0.733 and 0.755, respectively. Comparison of AUC showed no significant difference(P>0.05), which suggested that MRS, PSAD and f PSA/t PSA had similar performance in diagnosing prostate cancers at PSA gray zone.3. Diagnosis performance of MRS combined with PSAD(MRS+PSAD), MRS combined with fPSA/t PSA(MRS+ fPSA/tPSA), MRS combined with PSAD and fPSA/t PSA(MRS+PSAD+ fPSA/tPSA): The area under the ROC curves of MRS+PSAD, MRS+ f PSA/t PSA and MRS+PSAD+ fPSA/tPSA in diagnosing prostate cancers at PSA gray zone were 0.807, 0.797, and 0.880, respectively. When compared with MRS, the area under the ROC curves of MRS+PSAD and MRS+ f PSA/t PSA showed some degree but not significant increase(P>0.05); The area under the ROC curve of MRS+PSAD+ f PSA/tPSA showed significant increase(P<0.05).4. Decision curve analysis results showed that, when the probability threshold was greater than 20%, the net benefit of MRS+PSAD+ fPSA/t PSA was higher than that of MRS+PSAD and MRS+ fPSA/tPSA in diagnosing prostate cancers at PSA gray zone.Conclusions:1. PSA lack of specificity in diagnosing prostate cancers at PSA gray zone;2. MRS, PSAD and f PSA/tPSA all have certain value in diagnosing prostate cancers at PSA gray zone, and their diagnosis performance had no significant difference.3. Combined use of MRS, PSAD and fPSA/t PSA can improve the accuracy, sensitivity and specificity of diagnosing prostate cancer at PSA gray zone.4. According to decision curve analysis, the net benefit of MRS+PSAD+ fPSA/tPSA was greater than that of MRS+PSAD and MRS+ fPSA/tPSA in diagnosing prostate cancers at PSA gray zone, resulting in more patients avoiding unnecessary biopsy.