Oxidative stress measured by thioredoxin reductase level as potential biomarker for prostate cancer.

The aims of this study were to determine if Thioredoxin reductase (TR) is detected in the serum, and to establish the sensitivity and specificity of serum TR for diagnosing prostate cancer (PC). We assessed serum TR in 380 participants in the training cohort: 160 patients with PC, 120 with benign prostatic hyperplasia and 100 healthy individuals. The validation cohort comprised 320 participants: 120 with PC, 100 with BPH and 100 healthy individuals. TR was measured in serum by ELISA by independent researchers. The patients with PC were graded using the Gleason system. Receiver operating characteristic (ROC) curves were utilized to evaluate the accuracy of biomarkers to diagnose PC. The influence of serum levels of TR on tumor grade and metastasis was performed by binary logistic regression analysis. The median levels of serum TR in PC were significantly higher than that of healthy subjects and patients with BPH (P < 0.0001). Based on the ROC curve, the optimal cutoff value of serum TR levels as an indicator for auxiliary diagnosis of PC from BPH was projected to be 8.2 U/ml, which yielded a sensitivity of 81.8% and a specificity of 68.9%, with the area under the curve at 0.862 (95% CI, 0.821-0.903). Combined model (TR and PSA) showed a significantly greater discriminatory ability as compared with those markers alone. In regression analysis, after adjusting for other significant predictors, TR remained an independent metastasis predictor with an adjusted OR of 4.99 (95% CI, 2.64-8.09). Similarly, TR also was an independent High-grade tumors (HGT) predictor with an adjusted OR of 5.15 (95% CI, 2.52-9.14). Our study has demonstrated the additional benefit of TR measurement in the diagnosis of PC in the Chinese population. Further studies of the application of TR in this region may be beneficial.