Role of PSA-Related Variables in Improving Positive Ratio of Biopsy of Prostate Cancer within Serum PSA Gray Zone

Abstract

The aim of this study was to assess the validity of predictors of prostate biopsy outcome in order to improve their positive predictive value (PPV). The related variables of PSA such as free/total PSA ratio (F/T), complexed/total PSA ratio (C/T), density of PSA (PSAD) were studied to improve early diagnosis for early PCa within serum PSA gray zone. Samples of venous blood were collected early in the morning from 459 patients, aged 50 to 88 years (average 70.5 years old), whose serum T-PSA was between 4 to 10 ng/mL (153 cases of Pca, 306 cases of BPH). Serum T-PSA, F-PSA and C-PSA were determined by ELISA method; prostate volume was measured by transrectal ultrasound, then prostate biopsy was taken for all patients. Out of f 459 patients, 153 cases of Pca and 306 of BPH were diagnosed by prostate biopsy, whose mean values of T-PSA were 7.2 ± 1.25 ng/mL and 6.8 ± 0.96 ng/mL, respectively (P<0.05), of F/T were 0.117 ± 0.018 and 0.196 ± 0.021 (P<0.01), and of C/T they were 0.890 ± 0.023 and 0.754 ± 0.015 (P<0.01), of PSAD were 0.197 ± 0.023 and 0.106 ± 0.019 (P<0.01). The threshold of F/T>0.16 diagnosed 91 cases of cancer (59.5%), of C/T>0.84 88 cases (57.5%), of PSAD>0.15 94 cases (61.4%), and especially, of F/T>0.16 combined PSAD>0.15 80 cases whose sensitivity, specificity, accuracy, positive predictive values were 52.3%, 76.1%, 68.2%, 52.3%, respectively (P<0.05). There are some defects only in taking T-PSA as a biomarker for the diagnosis of PCa within serum PSA gray zone, and the threshold of F/T>0.16 combined PSAD>0.15 may be a new and significant indicator to provide a better basis for the diagnosis of early PCa.