KLK3 and prostate cancer: The European Randomized Study of Screening for Prostate Cancer (ERSPC) (Roobol and Schroder, 2003) and the Prostate Lung Colorectal and Ovarian cancer screening trial in the US (Prorok et al, 2000) offer screening by the PSA test in men aged 50–69 years (with some variation in age between participating countries).