KLK3 and prostate cancer: Ever smoking showed no association with prostate cancer risk in overall analyses (RR, 0.96; 95% CI, 0.93–1.00; P = 0.074), but an increased risk of prostate cancer in the pre-prostate-specific antigen screening era (RR, 1.05; 95% CI, 1.00–1.10; P = 0.046) and a lower risk of prostate cancer in the prostate-specific antigen screening era (RR, 0.95; 95% CI, 0.91–0.99; P = 0.011) were observed.