There have been many genes or proteins as biomarkers used in the clinical detection of cancer including alpha-fetoprotein (AFP) for liver cancer [3], BRCA1 and BRCA2 for breast and ovarian cancer [4], prostate specific antigen (PSA) for prostate cancer [5], and epidermal growth factor receptor (EGFR) for non-small-cell lung carcinoma [6]. Here, KLK3 is linked to prostate cancer.