KLK3 and Familial prostate cancer: Supplementation with 200 or 400 μg/day of selenium as selenised yeast reduced the risk of prostate cancer among men at high risk for the disease, according to a prostate specific antigen (PSA) level exceeding 4 ng/L, suspicious digital rectal examination, and a PSA velocity greater than 0.75 ng/mL/y [146].