Analyzing data from the Prostate Cancer Prevention Trial (which was unique in biopsying men with PSAs below 1 ng/ml), Thompson and colleagues reported that no PSA cutoff was associated with good test characteristics: for cutoffs up to 4 ng/ml, sensitivity and specificity ranged, respectively, from 21% to 83% and 39% to 94%; the positive predictive value varied from 7% to 27% (see [5]). Here, KLK3 is linked to Familial prostate cancer.