Usefulness of dynamic risk stratification in pediatric patients with differentiated thyroid carcinoma.

Purpose: Recently, the American Thyroid Association (ATA) dynamic risk stratification (DRS) has been verified to be more valuable than the static anatomical staging system for predicting prognosis in patients with differentiated thyroid carcinoma (DTC). The purpose of this retrospective study was to compare the clinical usefulness of DRS, which is based on the response to initial treatment, with that of ATA initial risk stratification in pediatric patients. Methods: A total of 144 pediatric patients underwent thyroid operation from August 1982 to December 2013 at Yonsei University Hospital (Seoul, Korea). Among them, 128 patients with complete clinical data were enrolled in this study. Clinicopathologic features and surgical outcomes were retrospectively analyzed by medical chart review. The mean follow-up duration was 11.5 years. Results: The mean tumor size was 2.1 cm; 80.4% of patients were diagnosed with conventional papillary thyroid carcinoma, and 7.0% of patients were diagnosed with follicular thyroid carcinoma. Low-risk patients had the highest probability of an excellent response to initial treatment (66.6%). High-risk patients had the highest probability of a structural incomplete response (100%) and the lowest probability of an excellent response (11.1%). The ATA risk stratification and the DRS system were independent risk factors for disease-free survival (DFS) (P = 0.041 and P < 0.001, respectively). Conclusion: The DRS system, which is based on the response to initial treatment, can offer more useful prognostic information compared with ATA risk stratification in pediatric patients with DTC.