KLK3 and cancer: Accordingly, several FDA-approved cancer biomarkers for non-invasive cancer detection, follow-up and prognosis are either glycans, such as CA19-9 (SLea), or heavily glycosylated glycoproteins, such as CA125 (MUC16), CA15-3 (MUC1), CA-72-4 (tumour-associated glycoprotein 72, TAG-72), PSA (prostate-specific antigen), and CEA (carcinoembryonic antigen) [233].