Context: Childhood thyroid cancer is of great concern after the Fukushima nuclear power plant accident. Baseline analytical data on thyroid ultrasound examination (TUE) in children are important for future studies.
Objective: We analyzed the age and sex distribution of findings from the TUEs of children and adolescents in the Fukushima Health Management Survey (FHMS).
Design, setting, and participants: From October 2011 through March 2014, 294,905 participants aged 18 years or younger at the time of the earthquake voluntarily had TUEs in the first round of the FHMS. A secondary confirmatory examination was performed in 2032 subjects. Age- and sex-dependent prevalence and size of thyroid cysts, nodules, and cancers were analyzed.
Main outcome measures: Age, sex, and size distribution of findings were analyzed.
Results: Thyroid cysts, nodules, and cytologically suspected cancers were detected in 68,009, 1415, and 38 male subjects and in 73,014, 2455, and 74 female subjects, respectively. There was an age-dependent increase in the detection rate of thyroid nodules and cancer, but that of cysts reached a peak at 11 to 12 years. Sex affected the prevalence of thyroid nodules and cancers after the onset of puberty, but only a small difference was exhibited in that of cysts.
Conclusions: The thyroid cancer detection rate in Fukushima was clarified, and the proportion of individuals with thyroid nodules and cysts varied substantially by age. The results of this study will contribute to future epidemiological research on nodular thyroid diseases in children and adolescents.