Applicability of Adults 2015 American Thyroid Association Differentiated Thyroid Cancer Guidelines for Postoperative Risk Stratification and Postradioiodine Treatment Dynamic Risk Stratification in Pediatric Population

Purpose This retrospective study aimed to study the applicability of 2015 adult American Thyroid Association (ATA) differentiated thyroid cancer (DTC) postoperative risk stratification and guidelines in the pediatric population for evaluating the number of metastatic lymph nodes in the postoperative risk stratification and postradioactive iodine (RAI) treatment dynamic risk stratification (DRS) using response to treatment (RTT) reclassification. In addition, the effect of pubertal status and gender was assessed on disease presentation and prognosis. Methods Data of 63 DTC patients aged 20 years or less, stratified into prepubertal, pubertal, and postpubertal age groups, was divided into low, intermediate, and high-risk groups using pediatric ATA recurrence risk stratification. Forty-seven patients were classified as responders (excellent and indeterminate responses) and incomplete responders (biochemical and structurally incomplete responses) by assessing the RTT at 1.5 years follow-up similar to recommendation of 2015 adult DTC ATA guidelines. Results Female-to-male ratio showed a trend of gradual increase with increasing age. Significantly more responders were observed in low- and intermediate-risk groups than in high-risk group ( p = 0.0013; p = 0.017, respectively), while prepubertal group had more extensive (N1b) disease. Using DRS at follow-up of 1.5 year, pubertal and postpubertal groups showed significantly better response to RAI. More female than male patients showed response and took significantly less time to respond to RAI ( p = 0.003). Conclusion RAI response in pediatric DTC depends on pubertal status, gender, and number of malignant nodes. DRS using RTT classification may be applicable early at 1.5 years after initial therapy in different pubertal age and risk groups.