KLK3 and Familial prostate cancer: For specific PSA values, prostate cancer was identified in 12% (three of 25 patients) with PSA levels of < 2.5 ng/mL, 12.7% (six of 47 patients) with PSA levels of ≥ 2.5–< 4.0 ng/mL, and in 30% (21/70 patients) with PSA levels ≥ 4.0 ng/mL [4].