Distant Metastases and Outcome of Pediatric Differentiated Thyroid Cancer.

Context: Distant metastases are fairly common in pediatric differentiated thyroid cancer (DTC). Objective: Our objectives were to study the predictive factors of distant metastases and the outcome of pediatric DTC. Methods: We studied all patients with pediatric DTC (age ≤ 18 years) managed over 21 years (January 2002-December 2022) at our institution. A total of 192 patients (33 males [17.2%], 159 females [82.8%]) with pediatric DTC were analyzed. The median age was 16 years (range, 5-18 years). Total thyroidectomy was performed in 97%, lymph node dissection in 86.4%, and radioactive iodine-131 (I-131) ablation/therapy was administered to 85.4% of the patients. Additional therapies were administered to 65 patients (33.9%). Thirty-five patients (18.2%) developed distant metastases. Results: At the last follow-up (median follow-up, 82.5 months; interquartile range 48-132), 124 patients (64.6%) had an excellent response, 47 (24.5%) had an indeterminate response, 5 (2.6%) were in a biochemically incomplete response, 15 (7.8%) were in a structurally incomplete response, and 1 patient (0.5%) died of thyroid cancer. While tumor size, extrathyroidal extension/invasion, and distant metastases were predictive of persistent/recurrent disease in a univariate analysis, only distant metastases remained consistently predictive of persistent/recurrent disease in a multivariate analysis ( Conclusion: In pediatric DTC, distant metastases are common, especially in patients with large tumor size and extrathyroidal extension. Distant metastases are the most important predictive factor of persistent/recurrent disease.