However, unlike the cases of prostate specific antigen (PSA) for prostatic cancer and α-fetoprotein (AFP) for liver cancer, up to now, there was no biomarker available for early warning of breast cancer in clinical practice except that invasive genetic test of BRCA1/2 mutation was recommended to evaluate the risk of hereditary breast cancer [39]. The gene discussed is KLK3; the disease is Hereditary breast cancer.