CEACAM5 and medullary thyroid gland carcinoma: Currently, following the newest ATA guidelines, a postoperative MTC risk stratification and long-term follow-up are mainly based on histopathological data (primary tumor stage, the presence of lymph node and/or distant metastases), and serum concentration of two biomarkers: calcitonin (Ctn) and carcinoembryonic antigen (CEA) (1).