KLK3 and prostate cancer: We investigated whether age and PSA were an effect modifier in association between exposure (rs4242382, rs2735839 and rs1447295) and outcome (prostate cancer), but the effect of rs4242382 (X2 = 0.756, X2 = 1.84), rs2735839 (X2 = 3.303, X2 = 4.68) and rs1447295 (X2 = 1.848, X2 = 0.184) on prostate cancer was not modified by age and PSA respectively.