Serum prostate-specific antigen to detect prostate carcinomas has a positive likelihood ratio of 1.85 [37], the Guaiac test used for bowel cancer screening has a positive likelihood ratio of 2.26 [38], and the screening mammography for the early detection of breast cancer has likelihood ratios ranging between 5.2 and 8.8 depending on the screened age group [39]. This evidence concerns the gene KLK3 and breast cancer.