Abstract
Increased detection of thyroid nodules using high-resolution ultrasonography has resulted in a world-wide increase in the incidence of differentiated thyroid cancer (DTC). Despite the steep increase in its incidence, the age-standardized mortality rate of thyroid cancer has remained stable, which leads toward a trend of more conservative treatment. The latest American Thyroid Association (ATA) guidelines for thyroid nodules and thyroid cancer revised in 2015 suggested that fine needle aspiration biopsy should be performed for thyroid nodules larger than 1 cm and lobectomy might be sufficient for 1 to 4 cm intrathyroidal DTC. In addition, active surveillance instead of immediate surgical treatment was also recommended as a treatment option for papillary thyroid microcarcinoma based on the results of a few observational studies from Japan. The Korean Thyroid Association (KTA) has organized a task force team to develop revised guidelines for thyroid nodules and DTC after an extensive review of articles and intense discussion on whether we should accept the changes in the 2015 ATA guidelines. This paper introduces and discusses the updated major issues and differences in the ATA and the KTA guidelines.