Radioiodine Therapy in Pediatric Differentiated Thyroid Cancer

Dosimetry, Clinical Care, and Future Challenges

Abstract

Thyroid cancer is very rare in children. ¹³¹I therapy after thyroidectomy is established in pediatric differentiated thyroid cancer (DTC). Pediatric DTC guideline is silent on the optimum amount of ¹³¹I that could be safely and effectively administered to children who are more radiosensitive. Like adult DTC, children are also given ¹³¹I therapy empirically based either on age or body weight. Pediatric DTC guideline recommends that patient-specific dosimetry is important in children. Still, due to the low incidence rate and the practical difficulties of dosimetry, it has neither been established nor adopted in routine practice. This review article aims to discuss current approaches of ¹³¹I therapy in children and young adult patients with DTC and dosimetric data obtained by several investigators. Efforts are required to simplify dosimetric procedures and precise results, especially in determining lesion size. We prefer 3-dimensional dosimetry over planar dosimetry, where lesion size could be measured accurately. ¹²⁴I PET/CT-based dosimetry is expected to give accurate dosimetric results. The most challenging aspect is that no randomized controlled trials are available to compare the empiric ¹³¹I therapy results versus dosimetry-based treatment outcomes in children and young adults. Suppose dosimetry-based ¹³¹I therapy could be shown to have better outcomes, namely, successful ablation rate, better disease-free survival, and lesser treatment-emergent adverse events than empirical ¹³¹I treatment. In that case, one can argue in favor of the former. Unfortunately, no convincing study is currently available. Thus, there is a need for a randomized control trial to settle this issue.