CEACAM5 and medullary thyroid gland carcinoma: Previous studies reported that MTC can synthesize and secrete a variety of bioactive substances, such as calcitonin (Ctn), carcinoembryonic antigen (CEA), and neuron‐specific enolase (NSE).5, 6, 7, 8, 9 Although numerous reports have shown that the expression levels of Ctn and CEA are related to cervical lymph node metastasis, the relationship between combined detection of serum markers and lateral lymph node metastasis (LLNM) in MTC patients is rarely studied.