KLK3 and prostate cancer: The primary objective was to quantify the cumulative incidence of PSA testing and opportunistic PSA screening between 1998 and 2017; the secondary objectives comprised identifying associations between PSA testing/opportunistic PSA screening rates and sociodemographic and protective/risk factors for prostate cancer.21,22 Furthermore, population-based estimates of the potential pre-randomisation testing and control-arm contamination of the CAP trial, based on time-period- and age-group-restricted analyses of the cohort, were derived.