For example, prostate-specific antigen (PSA) is affiliated with prostate cancer, human epididymis protein 4 (HE4) is related with ovarian cancer, alpha-fetoprotein (AFP) is associated with liver cancer, carcinogenic embryonic antigen (CEA) is linked with colon cancer, thyroglobulin (Tg) is associated with thyroid cancer, while HER2/NEU and CA15.3/CA27.29 is associated with breast cancer [9,10]. The gene discussed is KLK3; the disease is prostate cancer.