Risk of Thyroid Cancer in Children, Adolescents, and Young Adults with Hashimoto Thyroiditis: A 27-Year Follow-Up Study.

INTRODUCTION

Adult subjects with Hashimoto's thyroiditis (HT) have an increased risk of developing thyroid cancer. Whether children and adolescents with HT carry the same risk is still a matter of debate. The aim of the present study was to investigate the prevalence of thyroid nodules and cancer in pediatric autoimmune thyroiditis.

METHODS

A retrospective analysis was conducted on data from 1,050 adolescents and young adults (825 females, 225 males) who were regularly followed in nine Italian pediatric endocrinology centers. The median follow-up period was 5.8 years (range: 0.6-27.6 years). In all subjects, thyroid-stimulating hormone (TSH) and free thyroxine (fT4) levels were evaluated annually. Thyroid ultrasound was performed annually in patients with nodules and every 2 years in those without nodules.

RESULTS

A total of 245 nodules were detected, corresponding to a prevalence of 23.3%. This prevalence is significantly higher than that observed in a matched control population (4.7%). The prevalence of thyroid cancer was 0.95% (10 malignant nodules: 8 papillary and 2 papillary follicular variants). This rate is statistically higher than that observed in the control population (0.37%). The severity of hypoechogenicity on ultrasound, thyroid peroxidase antibodies (TPOAb), and serum fT4 concentration at diagnosis were predictive of the development of new nodules. Furthermore, a positive correlation was observed between TPOAb and the development of thyroid cancer.

CONCLUSION

Children, adolescents, and young adults with HT have an increased risk of developing thyroid nodules and cancer.