Initial and Dynamic Risk Stratification of Pediatric Patients With Differentiated Thyroid Cancer

Background The objective of this study was to evaluate the usefulness of American Thyroid Association (ATA) risk classification and dynamic risk stratification (DRS) based on the response to initial therapy in pediatric patients with differentiated thyroid cancer (DTC). Methods This historical cohort study included 77 pediatric patients with DTC who underwent thyroid surgery. Clinical outcomes during median 5.3 years of follow up were assessed according to 3 ATA risk groups and 4 DRS groups. Results In ATA risk classification, 22%, 48%, and 30% of patients were in the low-, intermediate-, and high-risk groups, respectively. There was no significant difference in disease-free survival (DFS) between the indeterminate and the low-risk group. The risk of recurrent/persistent disease was significantly higher only in the high risk group [hazard ratio (HR), 18.4; P = 0.005]. In DRS, 49%, 13%, 6%, and 31% of patients were classified in the excellent, indeterminate, biochemical incomplete, and structural incomplete response groups, respectively. The risk of recurrent/persistent disease was significantly higher in the indeterminate group (HR, 10.2; P = 0.045) and in the structural incomplete group (HR, 98.7; P = 0.005) compared with the excellent response group. Conclusions DRS based on the response to initial therapy could be useful in addition to initial ATA pediatric risk classification to predict recurrent/persistent disease in pediatric patients with DTC.