Children and adolescents may be at risk for overdiagnosis of thyroid cancer, according to the results of a population-based study published in The Lancet Diabetes and Endocrinology.

Data from 3 international databases (International Incidence of Childhood Cancer Volume 3 database, WHO mortality database, and cancer incidence in 5 continents database) comprising incidence data from 49 counties and mortality data from 27 countries were analyzed for this study. Temporal trends in incidence and mortality from 1998 to 2012 among individuals aged 0 to 19 years were assessed.

A total of 8049 cases of thyroid cancer were reported in 47 countries. There was considerable variability, ranging from 0.4 per 1 million person-years in Uganda and Kenya to 13.4 per 1 million person-years in Belarus. Stratified by gender, incidence ranged from 0.6 to 20.4 per 1 million person-years for girls and 0.3 to 6.8 per 1 million person-years for boys.

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More countries reported an increased incidence rate over time among girls aged 10 to 19 years than for boys, in which a significant increase was observed in 44% of 32 countries for girls compared with 31% for boys. Increases were highest for girls in Puerto Rico, Italy, Czech Republic, South Korea, and Turkey. Belarus reported a decreased incidence for both genders.

For the 25 countries for which data for both adolescents and adults were available, similar trends were reported for boys and men (r=0.83) and girls and women (r=0.82). Fewer youth were diagnosed with thyroid cancer than were adults in South Korea, India, Japan, and Norway; and more youth were diagnosed in Belarus and Italy.

Thyroid cancer mortality among children and adolescents was less than 0.1 per 1 million person-years from 2008 to 2012.

This study did not include information about tumor stage and size, which may have allowed for better understanding of the global prevalence of thyroid cancer overdiagnoses.

The study authors concluded that the pattern of thyroid cancer was similar between adolescents and adults. However, incidence in recent years has been increasing, which may indicate a pattern of overdiagnosis among younger patients. These findings suggested that youth who are not symptomatic do not require thyroid cancer screening, which may in turn help to reduce overdiagnoses.


Vaccarella S, Lortet-Tieulent J, Colombet M, et al; on behalf of the IICC-3 contributors. Global patterns and trends in incidence and mortality of thyroid cancer in children and adolescents: a population-based study. Lancet Diabetes Endocrinol. 2021;9(3):144-152. doi:10.1016/S2213-8587(20)30401-0