The elements of risk stratification may include pretreatment PSA, PSA velocity, Gleason score, volume of tumor or stage [55–57], PSA velocity or total value [38, 58], PSA nadir and time to recurrence after therapy [59, 60], and possibly the presence of circulating tumor cells [61], as all of these have been shown to be associated with increased risk of progression or death from prostate cancer. This evidence concerns the gene KLK3 and prostate cancer.