PCa is a complex and heterogeneous disease (D’Amico et al., 2003; Buyyounouski et al., 2012) since the risk of relapse and death after treatment differs among cancers with the same clinico-pathological features, namely the grade (Gleason score), stage [Tumor, Node, Metastasis (TNM)] (Edge and Compton, 2010; Amin et al., 2018) and the level of prostatic specific antigen (PSA) (Papsidero et al., 1980). The gene discussed is KLK3; the disease is cancer.