In the PSA high/Ki67 quartile 4-low tumors, the relatively few cases that died from prostate cancer had higher median Gleason score (7 vs. 6, P < 0.001), tumor stage; (2 vs. 1, P < 0.05), tumor content (60 vs. 10%, P < 0.001), and Ki67 index (2.7 vs. 1.2%, P < 0.01). This evidence concerns the gene KLK3 and prostate cancer.