IMPE Abstracts

Background: Pediatric papillary thyroid cancer (PTC) is traditionally treated with total thyroidectomy and radioactive iodine (RAI). However, growing evidence suggests that not all patients benefit from RAI. Our objective was to describe clinicopathologic features and outcomes of patients with pediatric PTC who did not receive upfront adjuvant RAI therapy.

Methods: Using an IRB-approved database at a tertiary referral cancer center, we performed a retrospective analysis evaluating patients aged ≤ 18 years diagnosed with stage I PTC between 01/01/2000-31/08/2021. Inclusion criteria included: follow u P≥ one year and no intended therapeutic RAI within one year of diagnosis. Patient demographics, tumor characteristics, management, and disease status utilizing dynamic risk stratification were studied.

Results: Of 417 pediatric PTC patients, 81 patients (89% female) met the study criteria. Median age of diagnosis was 16 years (interquartile range [IQR] 15-17 years; range 4-18 years). Surgical management included: total thyroidectomy (n=56, 69%), lobectomy (n=15, 19%), two-stage thyroidectomy (n=7, 9%), and a Sistrunk procedure for ectopic PTC (n=3, 4%); an initial therapeutic or prophylactic neck dissection was performed in 48/81 cases (59%). Median tumor size was 18 mm [IQR 14-25 mm], and 51% (n=41) of patients had pathologically identified nodal disease (N1a=28; N1b=14). American Thyroid Association (ATA) risk stratification was low-, intermediate-, and high-risk in 52 (67%), 21 (27%), and 5 (6%) evaluable patients, respectively. In the overall group, with a median follow-up of 6 years [IQR 2-8 years], only three patients (4%) had structural disease identified: one achieved remission after RAI followed by further surgery for persistent cervical disease, one had biopsy-proven central neck disease not treated with RAI, and the third had a delayed diagnosis of pulmonary metastatic disease that was not iodine-avid on a post-therapy scan. In the lobectomy group, after a median follow up of 2 years [IQR 2-5 years], there were no structural recurrences. Overall, disease status at last clinical follow-up was 74% excellent response, 22% indeterminate, 1% biochemical, and 3% structural incomplete. Among the indeterminate responses, many were secondary to residual normal thyroid tissue or persistent but declining thyroglobulin antibodies and were otherwise considered to be disease free.

Conclusion: In selected pediatric PTC patients, including those with cervical lymph node metastases, initial treatment without adjuvant RAI is associated with excellent short-term outcomes, suggesting that RAI can be safely withheld in patients who have no evidence of disease after therapeutic surgery. Longer follow up will be important to confirm these findings.