Thyroid storm after intensity-modulated radiation therapy: a case report and discussion.

A 43-year-old man with locally advanced squamous cell carcinoma of the base of tongue was treated with induction chemotherapy followed by intensity-modulated radiation therapy (IMRT). Within 20 days post-treatment, the patient developed clinical symptoms highly suggestive of hyperthyroidism. Two and one half months after completion of therapy, the patient developed severe thyrotoxicosis, which, in retrospect, appears to have met the criteria for thyroid storm. This case history illustrates a previously unreported, life-threatening complication of external-beam radiation that should be considered in patients receiving IMRT therapy involving the thyroid. Diagnosis of the patient's hyperthyroidism and probable thyroid storm was difficult to recognize because of the significant overlap between the signs and symptoms of severe thyrotoxicosis and the expected toxicities of his cancer therapy.