In further analysis we found that this effect was particularly pronounced among older GPs; compared to GPs aged < 50 who had not has a patient diagnosed with prostate cancer through a PSA test, GPs aged ≥ 50 who had had such a patient were 6-times more likely to routinely PSA test asymptomatic men (multivariate OR = 6.11, 95% CI 3.96–9.25). Here, KLK3 is linked to prostate cancer.