Firstly, diagnosed with MTC in 1995/presented with a large right thyroid nodule/elevated calcitonin and then thyroidectomy/RET negative/26 LNs were involved with metastasis/elevated calcitonin and CEA/reevaluation with CT scan showed hila, mediastinum, lungs, liver, bones, and kidney were progressively involved/C634R mutation in the RET proto‐oncogene was detected. Here, CEACAM5 is linked to medullary thyroid gland carcinoma.