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

Abstract

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. 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. 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. Outcomes were response to therapy and disease status, mortality, and treatment toxicity. 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 μg /L], 69 (30.1%) showed nearly complete remission (complete response, except stimulated Tg 1-10 μg/L), and 11 (4.8%) had partial remission (Tg > 10 μg/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. 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 suboptimally treated, response to subsequent RIT and final outcomes are mostly favorable.