Elevation of serum carcinoembryonic antigen level in a patient with hypothyroidism after radiation therapy for cervical esophageal cancer.

We report the case of a 51-year-old woman who showed elevation of serum carcinoembryonic antigen (CEA) level 14 months after chemoradiation therapy for her cervical esophageal cancer. Close examination demonstrated that the patient was suffering from hypothyroidism probably due to the chemoradiation therapy. The serum CEA level decreased after starting supplementary treatment with oral levothyroxine. The exact mechanism underlying the elevated level of CEA observed in a patient with hypothyroidism is unclear. However, we should be aware of the possibility of transient elevation of CEA affected by thyroid function in patients after radiation therapy for head and neck cancer.