Outcomes of Children and Adolescents with Well-Differentiated Thyroid Carcinoma and Pulmonary Metastases Following 131 I Treatment: A Systematic Review

Background: The optimal dose and efficacy of 131 I treatment of children and adolescents with well-differentiated thyroid carcinoma (WDTC) and pulmonary metastases are not well established. A therapeutic challenge is to achieve the maximum benefit of 131 I to decrease disease-related morbidity and obtain disease-free survival while avoiding the potential complications of 131 I therapy. Summary: We systematically reviewed the published literature on children and adolescents with WDTC and pulmonary metastases treated with 131 I to examine outcomes after 131 I administration and the risks and benefits of therapy. After reviewing 14 published articles, 9 articles met our inclusion criteria encompassing 112 pediatric and adolescent patients with WDTC and pulmonary metastases 21 years of age or younger at diagnosis spanning a follow-up period of 0.6–45 years. 131 I therapy after surgery and thyrotropin suppression resulted in complete, partial, and no disease response in 47.32%, 38.39%, and 14.29% of patients, respectively. Five studies provided data on disease response in relation to 131 I dose. In general, nonresponders received the highest 131 I doses and complete responders received a higher dose than partial responders. The disease-specific mortality rate was 2.68%. Survival was 97.32%. A second primary malignancy occurred in one patient. One out of 11 patients studied experienced radiation fibrosis. Conclusions: This review confirms that the majority of pediatric and adolescent patients with WDTC and pulmonary metastases treated with 131 I do not achieve complete response to therapy, yet disease-specific morbidity and mortality appear to remain low. It is therefore prudent to use caution in the repeated administration of 131 I to such patients to ensure that adverse effects of therapy do not cause more harm than good in a disease that has an overall favorable natural course. Long-term prospective studies are needed to analyze disease-specific morbidity and mortality, recurrence rate, dose-specific response, and dose-related adverse effects of 131 I in this patient population.