Finally, receiver operating characteristic (ROC) curves revealed that, although Proteobacteria failed to distinguish prostate cancer from BPH, it had better potential in predicting distant metastasis than PSA level (tended to be higher in patients with metastatic prostate cancer) (area under the ROC curve, 0.860; p < 0.001) (Fig. 6E). Here, KLK3 is linked to prostate carcinoma.