Long-term outcomes of patients diagnosed with differentiated thyroid cancer in childhood and young adulthood

Abstrac Context Rates of pediatric differentiated thyroid cancer (DTC) in the United States have been increasing while studies on this population remain limited by inconsistent age cut-offs, short follow-up periods, or relative lack of clinical data. Objective To report long-term outcomes in patients diagnosed with DTC at age 20 years old and younger. Methods A retrospective study was conducted of patients diagnosed with DTC at age 20 years old or younger with long-term follow-up. Results 155 patients were included with a median age at diagnosis of 17 years (9 to 20 years). The frequency of distant metastasis and larger tumor size were inversely related to age at diagnosis (overall stage p = 0.045, T-stage (size of the primary tumor ± invasion) p = 0.001). The median duration of follow-up was 16 years (1 to 63 years) and at last follow-up, 52.3% of patients had excellent response and disease specific mortality was 0%. There was no difference in response to therapy based on histologic subtype or birth sex; however, younger age at diagnosis was associated with worse response (p = 0.046). Patients with over 50 years of follow-up (n = 9) had median of 36 years of stability, with progression occurring in 6 out of 9 (67%) patients. Conclusions Patients diagnosed with DTC as children or young adults have outstanding long-term survivorship, but may experience disease progression later in life, suggesting that long-term follow-up might be appropriate for this population. Younger age at diagnosis was identified as a risk factor for distant metastases and poorer response to therapy.