Prevalence of thyroid cancer in hyperthyroidism treated by surgery.

The reported prevalence of thyroid cancer with concurrent hyperthyroidism varies from 0.21% to 9.0%. This variability may be due to multiple factors, such as indications for surgery and histopathologic accuracy. However, this condition is not rare and its prevalence has increased in recent surveys, perhaps as a result of more detailed examinations. The aim of this retrospective study was to determine the prevalence of thyroid cancer in hyperthyroid patients at surgery. Forty-five patients, 34 women and 11 men, underwent surgery for hyperthyroidism in our department between 1989 and 2000. Ages ranged from 14 to 67 years. There were 42 cases of Graves' disease, one of functional multinodular goiter, and two of single toxic nodules. Forty-three patients underwent total thyroidectomy and two underwent total lobectomy. Six cases (13.3%) of thyroid cancer were found, two men and four women with ages ranging from 19 to 48 years. Final histologic examination revealed three papillary carcinomas, one follicular carcinoma, one follicular carcinoma combined with clear-cell carcinoma, and one clear-cell carcinoma. Thus, in our department, the prevalence of thyroid cancer in hyperthyroidism treated using surgery was 13.3%. Our study showed that even a single toxic nodule may occur with concurrent thyroid cancer. Careful evaluation of such patients is needed to exclude the presence of associated malignancy and to determine the most appropriate therapeutic plan.