The frequency of cold thyroid nodules and thyroid malignancies in patients from an iodine-deficient area.

An analysis of thyroid cancer morbidity was carried out in two adjacent areas of Sicily differing in iodine intake. A consecutive series of 911 patients with "cold" nodules from an iodine-deficient area (IDA) and 2537 from a control area (CA) were examined by fine needle aspiration and selected for surgery and pathologic examination. Malignancies were found in 27 of the patients (2.96%) from the IDA and in 139 patients (5.48%) from the CA. Based on a population survey indicating that "cold" thyroid nodules were 2.5 times more frequent in the IDA with respect to the CA, we calculated a prevalence of 127 thyroid cancers per 10(5) inhabitants in the IDA versus 93 in the CA (P less than 0.001). Moreover, follicular and anaplastic carcinomas were three times more frequent in the IDA than in the CA (75 versus 24 cases per 10(5) inhabitants, respectively). These studies indicate that iodine deficiency may be one factor in the development of certain thyroid malignancies in man.