The Role of American Thyroid Association Pediatric Thyroid Cancer Risk Stratification and BRAF^V600E Mutation in Predicting the Response to Treatment in Papillary Thyroid Cancer Patients ≤18 Years Old

INTRODUCTION: This study aimed to evaluate the role of risk stratification by the American Thyroid Association (ATA) pediatric thyroid cancer risk levels and BRAFV600E 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, BRAFV600E 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. BRAFV600E mutation analysis data was available in 55 (78.6%) patients, of whom 18 (32.7%) had the BRAFV600E 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 BRAFV600E positive and negative patients were 83% and 92%, respectively (p=0.339). The rate of locoregional recurrence was significantly higher in BRAFV600E positive vs negative patients (33.3% vs 2.7% respectively, p=0.001).
DISCUSSION AND CONCLUSION: ATA pediatric risk stratification is effective in predicting response to treatment in PTC patients ≤18 years old. The presence of BRAFV600E mutation was highly predictive for recurrence but had no significant impact on the rate of excellent response to treatment at final follow-up.