The use of fine needle aspiration and trends in incidence of thyroid cancer in Taiwan

Background: Thyroid cancer is the most prevalent endocrine malignancy, and the incidence of thyroid cancer has increased worldwide. Fine needle aspiration (FNA) for cytology of thyroid tissue is used for differentiating thyroid cancers from benign thyroid nodules. Overuse of FNA may detect subclinical thyroid cancer and play a role in the increased incidence of thyroid cancer. The aim of this study was to evaluate trends in incidence of thyroid cancer and the use of palpation-guided FNA thyroid and ultrasound-guided FNA thyroid in Taiwan. Methods: By retrospectively analyzing a cohort dataset of one million people randomly sample to represent as NHI beneficiaries of Taiwan National Health Insurance Research Database from 2004 to 2010, patients who received palpation-guided and ultrasound-guided thyroid FNA were identified. Individuals who were diagnosed as having thyroid cancer were determined. Age-standardized, yearly rates of palpation-guided thyroid FNA and ultrasound-guided FNA, and age-standardized, yearly incidence rates of thyroid cancer were calculated. Results: In the study period, a total of 541 patients were newly diagnosed with thyroid cancer, 14,240 individuals received palpation-guided thyroid FNA, and 3823 individuals underwent ultrasound-guided thyroid FNA. There was a 94.8% increase in the age-standardized annual incidence rate of thyroid cancer. The age-standardized rates of palpation-guided thyroid FNA and ultrasound-guided thyroid FNA increased by 10.9% and 349.3%, respectively. Conclusion: FNA for cytology of thyroid tissue, especially ultrasound-guided FNA, was conducted by physicians more frequently in Taiwan. Increased use of FNA, especially ultrasound-guided FNA for cytology of thyroid tissue, may attribute to the increased incidence of thyroid cancer in Taiwan.