Laryngeal malignancy following iodine-125 therapy for thyrotoxicosis.

A 52-year-old woman presented with a laryngeal sarcoma eight years after receiving two doses, each of 30 mCi, of iodine-125 for thyrotoxicosis. That extrathyroidal tissue receives a higher radiation dose of low-energy photon radiation from iodine-125 than from an equivalent microcurie dose of iodine-131 and that the tumour was of a type which rarely arises spontaneously in the larynx suggest a possible link between the development of the tumour and iodine-125 therapy.