Thyroid cancer prevalence after radioiodine treatment of hyperthyroidism

The definitive treatment of hyperthyroidism in Europe is quite different fr om that in the United States. In Europe, the surgical approach is often pre ferred and considered safer than radioiodine treatment. European doctors us ually prefer to surgically remove the thyroid and perform a pathologic exam ination of it. They consider it to be an essential diagnostic tool to ident ify possible diseases that might be associated with hyperthyroidism and eve n to detect the rare thyroid tumors that might be associated with thyroid h yperfunction. The aim of this study was to evaluate whether radioiodine the rapy could be a risk factor for the misdiagnosis of thyroid cancer. Methods : We performed a retrospective revision of data we collected from 6647 pati ents (1171 [17.5%] men, 5476 [82.5%] women), all of whom underwent I-131 th erapy for hyperthyroidism from 1970 to 1997. Of the whole group, 6.5% were younger than 40 y, 33.5% were 40-60 y old, and 60% were older than 60 y. Mo reover, 5061 (76%) patients had either an autonomously functioning node or a toxic multinodular goiter. The other 1586 (24%) patients had Graves' dise ase. Results: After treatment, thyroid cancer was discovered in 10 (0,15%) patients, none of whom belonged to the group Of patients with G raves' dise ase. Five of these patients were treated during a period from 1970 to 1980, when sonography was not routinely available. The incidence of thyroid canc er in the series of radioiodine-treated patients (150/100,000 over a 27-y p eriod) was not significantly different from its incidence in the general po pulation. The expected rate is 124.88 per 100,000 over a 27-y period. Concl usion: An accurate preliminary evaluation (clinical examination, sonography , and cytologic evaluation of fine-needle aspiration) is fundamental for a proper choice between radioiodine and surgical therapy .