The Role of American Thyroid Association Pediatric Thyroid Cancer Risk Stratification and BRAFV600E Mutation in Predicting the Response to Treatment in Papillary Thyroid Cancer Patients ≤18 Years Old.

Objective: This study aimed to evaluate the role of risk stratification by the American Thyroid Association (ATA) pediatric thyroid cancer risk levels and BRAF^V600E mutation to predict the response to treatment in papillary thyroid cancer (PTC) patients ≤18 years old. Methods: Clinical outcomes during a median period of 6 (2-21.8) years were assessed in 70 patients, according to ATA pediatric risk stratification, BRAF^V600E mutation status, and dynamic risk stratification (DRS) at final follow-up. Results: Of 70 patients, 44 (63%), 14 (20%), and 12 (17%) were classified initially as low-, intermediate-, and high-risk, respectively. BRAF^V600E mutation analysis data was available in 55 (78.6%) patients, of whom 18 (32.7%) had the BRAF^V600E mutation. According to the final DRS, 61 (87%), two (3%), six (9%), and one (1%) patients were classified as an excellent, incomplete biochemical, incomplete structural, and indeterminate response, respectively. All ATA low-risk patients showed excellent response to treatment, whereas the rate of excellent response was 65.4% in intermediate- and high-risk levels (p<0.001). The rates of excellent response in BRAF^V600E positive and negative patients were 83% and 92%, respectively (p=0.339). The rate of locoregional recurrence was significantly higher in BRAF^V600E positive vs negative patients (33.3% vs 2.7% respectively, p=0.001). Conclusion: ATA pediatric risk stratification is effective in predicting response to treatment in PTC patients ≤18 years old. The presence of BRAF^V600E mutation was highly predictive for recurrence but had no significant impact on the rate of excellent response to treatment at final follow-up. [ABSTRACT FROM AUTHOR]