Long-Term Outcomes of Patients Diagnosed With Differentiated Thyroid Cancer in Childhood and Young Adulthood.

[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 cutoffs, short follow-up periods, or relative lack of clinical data.

[OBJECTIVE] This work aimed to report long-term outcomes in patients diagnosed with DTC at age 20 years and younger.

[METHODS] A retrospective study was conducted of patients diagnosed with DTC at age 20 years or younger with long-term follow-up.

[RESULTS] A total of 155 patients were included with a median age at diagnosis of 17 years (9-20 years). The frequency of distant metastasis and larger tumor size were inversely related to age at diagnosis (overall stage P = .045; T-stage (size of the primary tumor ± invasion); P = .001). The median duration of follow-up was 16 years (1-63 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 = .046). Patients with more than 50 years of follow-up (n = 9) had a median of 36 years of stability, with progression occurring in 6 out of 9 (67%) patients.

[CONCLUSION] 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.