Validation of dynamic risk stratification in pediatric differentiated thyroid cancer.

PURPOSE: There has been increasing interest in a risk-adopted management strategy known as dynamic risk stratification following the revised American Thyroid Association guidelines for differentiated thyroid cancer. We aimed to evaluate the usefulness of dynamic risk stratification for predicting structural disease in pediatric differentiated thyroid cancer patients.

METHODS: We retrospectively reviewed 130 pediatric differentiated thyroid cancer patients (≤19 years) who were treated between 1996 and 2015 at Samsung Medical Center. Patients were stratified according to three American Thyroid Association initial risk group (low, intermediate, or high risk) and four dynamic risk stratification group (excellent, indeterminate, biochemical incomplete, or structural incomplete).

RESULTS: Based on dynamic risk stratification strategy, structural disease was identified 3.9% in the excellent group, 9.7% in the indeterminate group, 76.9% in the biochemical incomplete group, and 100% in the structural incomplete group. The hazard ratios of the structural disease were 18.10 (P < 0.001) in the biochemical incomplete group, and 19.583 (P < 0.001) in the structural incomplete group compared to the excellent group. The prevalence of structural disease also increased as American Thyroid Association initial risk classification increased (5.9% in the low-risk group, 13.6% in the intermediate-risk group, and 45% in the high-risk group). The hazard ratios of structural disease in the high-risk group was 10.296 (P < 0.001) in compared to the low-risk group.

CONCLUSION: Dynamic risk stratification based on patient responses to initial therapy was able to effectively predict the risk of structural disease in a pediatric population, and as a follow-up strategy, may work as well in pediatric differentiated thyroid cancer patients as it does in adult differentiated thyroid cancer patients.