In the recommendations of the American Society of Clinical Oncology (ASCO), National Academy of Clinical Biochemistry (NACB), and the European Group on Tumor Markers (EGTM), determination of CEA is recommended after surgical removal of the tumor in patients with colorectal cancer every 2–3 months for at least 3 years, for the early detection of recurrence or metastasis. The gene discussed is CEACAM5; the disease is colorectal cancer.