KLK3 and breast cancer: Biomarkers currently used to detect the most prevalent cancers (Figure 4) are alpha-fetoprotein (αFP) (testicular and hepatocellular cancer), human chorionic gonadotrophin (β-HCG) (testicular cancer), calciton and thyroglobulin (thyroid cancer), cancer antigen (CA) 125 (ovarian cancer), CA 19.9 (pancreatic cancer), CA 15.3 (breast cancer), carcinoembryonic antigen (CEA) (colorectal cancer), paraproteins (myeloma), and prostate-specific antigen (PSA) (prostate cancer) [70].