Several sialylated proteins have been approved as cancer biomarkers, including prostate-specific antigen (PSA) used for screening of PC, α-fetoprotein used for diagnosis and monitoring of HCC, CA125 that detects the mucin glycoprotein MUC16 in ovarian cancer and thyroglobulin for thyroid cancer [2]. The gene discussed is KLK3; the disease is thyroid gland carcinoma.