Although the European Group on Tumor Markers has recommended the use of CEA and CA15-3 for assessing prognosis and early detection of disease progression in breast cancer since 2005 [25], the American Society of Clinical Oncology (ASCO) and National Comprehensive Cancer Network (NCCN) guidelines have not recommended the routine utilization of CEA and CA15-3 [26, 27]. The gene discussed is CEACAM5; the disease is breast cancer.