Is There a Role for External Radiation Therapy in Pediatric Differentiated Thyroid Cancer?

A BSTRACT Introduction: Pediatric differentiated thyroid carcinoma (DTC) has a higher incidence of locally advanced disease than adults. The efficacy of external beam radiation therapy (EBRT) prior to radioactive iodine ablation (RAIA) for inadequate resection and gross residual is established in adults, but not supported in children. Aim: The aim of this study was to evaluate the efficacy and toxicity in pediatric DTC patients who received EBRT prior to RAIA. Methodology: Data from November 2005 to November 2025 were retrospectively analyzed. Those who received EBRT to the neck prior to RAIA were included. The toxicity profile and response to RAIA were recorded. Results: A total of 112 children had DTC, of which 8 (3 females, 5 males, age range: 8–17 years, and mean: 12 years) were included. Six received conventional RT [40 Gy in 20 fractions followed by electron boost (16–20 Gy)]. Two received intensity-modulated radiation therapy (60–66 Gy). Total whole body scintigraphy scan (TWBS) showed residual disease in postoperative bed in 1, residual with lung metastases in 4, residual with nodal metastases in 2 and negative scan in 1 patient. Range of first stimulated serum thyroglobulin was 61-2400 ng/ml. Cumulative dose of RAIA ranged from 75 to 395 mCi. All showed significant biochemical and scintigraphic decrease. Response according to the American Thyroid Association (2025) was excellent in four, structurally incomplete in two and biochemically incomplete in two at the end of follow-up (median follow-up: 11.5 years and range: 1–23 years). Except for hypertrophic scar, none had significant patient-reported side effects. Conclusion: EBRT is a feasible adjuvant treatment option for selected pediatric DTC patients with locally aggressive disease – gross extrathyroidal extension or unresectable disease.