Twenty-Five Years After Chernobyl: Outcome of Radioiodine Treatment in Children and Adolescents With Very High-Risk Radiation-Induced Differentiated Thyroid Carcinoma

Context: After severe reactor emergencies with release of radioactive iodine, elevated thyroid cancer risk in children and adolescents is considered the main health consequence for the population exposed. Design: We studied thyroid cancer outcome after 11.3 years' median follow-up in a selected, very high-risk cohort, 234 Chernobyl-exposed Belarusian children and adolescents undergoing postsurgical radioiodine therapy (RIT) in Germany. Interventions: Cumulatively 100 children with or (without; n = 134) distant metastasis received a median 4 (2) RITs and 16.9 (6.6) GBq, corresponding to 368 (141) MBq/kg iodine-131. Main Outcome Measures: Outcomes were response to therapy and disease status, mortality, and treatment toxicity. Results: Of 229 patients evaluable for outcome, 147 (64.2%) attained complete remission [negative iodine-131 whole-body scan and TSH-stimulated serum thyroglobulin (Tg) < 1 mu g/L], 69 (30.1%) showed nearly complete remission (complete response, except stimulated Tg 1-10 mu g/L), and 11 (4.8%) had partial remission (Tg > 10 mu g/L, decrease from baseline in radioiodine uptake intensity in >= 1 focus, in tumor volume or in Tg). Except for 2 recurrences (0.9%) after partial remission, no recurrences, progression, or disease-specific mortality were noted. One patient died of lung fibrosis 17.5 years after therapy, 2 of apparently thyroid cancer-unrelated causes. The only RIT side effect observed was pulmonary fibrosis in 5 of 69 patients (7.2%) with disseminated lung metastases undergoing intensive pulmonary surveillance. Conclusions: Experience of a large, very high-risk pediatric cohort with radiation-induced differentiated thyroid carcinoma suggests that even when such disease is advanced and initially sub-optimally treated, response to subsequent RIT and final outcomes are mostly favorable.