Examples of prognostic biomarkers are Prostate-Specific Antigen (PSA) in prostate cancer and the phosphatidylinositol 3-kinase (PIK3CA) mutation status of tumours - which are associated with human epidermal growth factor receptor 2 (HER2) in women with positive metastatic breast cancer6. This evidence concerns the gene KLK3 and Familial prostate cancer.