Thyroid Cancer Screening and Overdiagnosis in Korea

Thyroid cancer incidence has increased worldwide. The country where the incidence has increased most is Korea. The strong association between thyroid cancer screening and the incidence of thyroid cancer suggests that screening is the most important factor in the epidemic of thyroid cancer. Other evidence for increased detection is widespread use of ultrasonography and fine-needle aspiration cytology, the concentrated increase in small-sized carcinomas, particularly papillary carcinoma. Because thyroid cancer screening did not have association with a decrease in thyroid cancer mortality, the observed rise in thyroid cancer incidence has raised concerns around overdiagnosis. Increased detection due to screening results in more harm than benefit in terms of psychological stress, unnecessary surgery, and financial burden. The fact that thyroid cancer screening is converting a substantial number of asymptomatic persons to cancer patients without benefit merits serious consideration.