Prevalence of thyroid cancer in 1894 patients with surgically treated thyroid nodules

Background - The study determined the prevalence of thyroid cancer in thyroid nodules diagnosed in one medical center and investigated the final histopathological results after ultrasonography and fine-needle aspiration cytology (FNAC) of these thyroid nodules. Methods - The study reviewed 11,656 consecutive patients with neck nodules diagnosed by thyroid ultrasonography with FNAC retrospectively from 1984 to 1994. Of these patients, 10,544 (90.5%) were diagnosed with benign lesions. Surgical treatments were suggested for 374 indeterminate, 24 Hurthle cell tumor and 497 suspected malignancies diagnosed by FNAC. Results -1,894 cases (16.3%) received surgical treatment. Benign lesions were subsequently diagnosed in 1,465 patients. Thyroid malignancy was histopathologically confirmed in 429 cases, including 320 papillary thyroid carcinomas, 62 follicular carcinomas, 18 anaplastic carcinomas, 12 metastatic carcinomas, 7 lymphomas, 7 medullary thyroid carcinomas, and 3 Hurthle cell carcinomas. In this series, histopathologically proven thyroid cancer was 3.7%; the overall estimated prevalence of thyroid malignancy was 5.1%. A relatively higher percentage of 29.2% of the thyroid cancer in thyroid nodules was observed in patients older than 50 years, as well as in patients younger than 20 years (26.7%). Prevalence of thyroid cancer in the thyroid nodules seemed to have been increasing during the past 11 years in Taiwan. Conclusions - In this large series, the prevalence of thyroid cancer in thyroid nodules was not higher than than that observed in other areas. A higher frequency of thyroid cancer was observed in patients younger than 20 and older than 50. Aggressive treatment is indicated for older patients, due to the higher frequency of invasive thyroid cancer.