Postoperative monitoring of serum carcinoembryonic antigen (CEA) and serum Ctn levels provide valuable information about the potential presence of residual disease.2,3 As more data become available, it has been shown that dynamic risk stratification with adjusted response to initial therapy could offer more useful prognostic information than anatomic staging systems in MTC. Here, CEACAM5 is linked to medullary thyroid gland carcinoma.