However, the US Food and Drug Administration (FDA) approved that none of these is routinely used for early clinical diagnosis, except a few of them for example, CA125 (also known as mucin 16) for ovarian cancer, prostate-specific antigen (PSA) for prostate cancer and CA19-9 for pancreatic cancer have been proposed to be useful for longitudinal disease monitoring (Füzey et al., 2013; Pavlou et al., 2013; Menon et al., 2015). Here, KLK3 is linked to ovarian cancer.