CEACAM5 and thyroid nodule: Besides, several well-known tumor markers, like carcinoembryonic antigen (CEA), carbohydrate antigen 19–9 (CA19–9) and calcitonin levels [12], have been proposed to be prthyroid noduleognostic factor in metastatic medullary thyroid carcinoma [13]; however, its role between tumor immunity and low risk thyroid nodules needs further elucidation.