KLK4 and prostate cancer: A second study in a small Korean sample set of 117 breast cancer cases and 194 controls found KLK4 SNP rs806019 to be associated with a decreased risk of breast cancer (Odds Ratio 0.53; 95% Confidence Interval 0.33–0.85; P = 0.007) [49], a finding of similar magnitude and direction to that observed in our study of prostate cancer.