KLK3 and breast cancer: For the diagnosis of cancer, many identities are used, i.e., tumor necrosis factor-alpha (TNF-α), α-fetoprotein (AFP), antigen 125 (CA125), cancer antigen 153 (CA15-3), cancer antigen 19-9 (CA19-9), epidermal growth factor receptor (EGFR), carcinoembryonic antigen (CEA), breast cancer (BRCA), human epidermal growth factor receptor 2 (HER2), interleukins (ILs), prostate-specific antigen (PSA), mucin 1 (MUC 1), vascular endothelial growth factor (VEGF) and squamous cell carcinoma antigen (SCC-Ag) [113,114].