Malignant disease following Iodine-131 therapy in Sweden

Since the introduction of /sup 131/I therapy for hyperthyroidism in 1941, this radionuclide has become the one most commonly employed in the treatment of thyroid diseases. The interpretation of the results from all available studies dealing with radiation exposure from /sup 131/I is difficult because the follow-up times are short, the patient groups are often small, or control groups are lacking. The carcinogenic risks of /sup 131/I have therefore not yet been adequately assessed, and further studies are needed. The present study was designed to analyze the incidence of malignant tumors and leukemia in a relatively large Swedish series of patients treated with /sup 131/I for hyperthyroidism at one institution and determine whether or not an increased risk of radiation-induced tumors could be detected