A Comprehensive Review of the Progress and Evaluation of the Thyroid Ultrasound Examination Program, the Fukushima Health Management Survey

Abstract

The Great East Japan Earthquake on March 11, 2011, and the subsequent tsunami caused an accident at the Fukushima Daiichi Nuclear Power Plant, in which extensive damage to the nuclear power reactors resulted in massive radioactive contamination. Fukushima Prefecture implemented the Thyroid Ultrasound Examination (TUE) program as part of the Fukushima Health Management Survey project in response to residents’ anxieties about health risks due to radiation exposure for residents aged 0–18 years at the time of the nuclear accident. This program consisted of the primary examination and the confirmatory examination. In the primary examination, thyroid nodules and cysts were examined using portable ultrasound apparatuses. The confirmatory examination was performed to have clinical or cytological diagnosis. As of June 30, 2021, 116, 71, 31, 36, and 9 examinees in the first, second, third, and fourth round of surveys, and the survey at age 25 years, respectively, were determined to have nodules cytologically diagnosed as malignant or suspicious for malignancy. The confirmatory examination of the fourth-round survey and the primary and confirmatory examination of fifth-round survey are currently in progress. Together with the low thyroid absorbed radiation dose estimated in the United Nations Scientific Committee on the Effects of Atomic Radiation 2020 report, our results suggested that the increased incidence of childhood thyroid cancer in Fukushima Prefecture was not caused by radiation exposure, but rather by the highly sensitive detection method. As detailed in this review, there were ongoing challenges in our program, such as actions against the risk of overdiagnosis and psychological support for participants and their families.

Achievements and Current Status of the Fukushima Health Management Survey

“…As of June 30, 2020, a total of 246 examinees in the baseline, 2 nd , 3 rd , and 4 th survey at aged 25 years were determined to have nodules cytologically diagnosed as malignant or suspicious for malignancy. 8 …”

“…Protocols in the FHMS have been reported elsewhere. 1 , 6 In brief, the FHMS consists of the Basic Survey 7 and four detailed surveys: the Thyroid Ultrasound Examination, 8 Comprehensive Health Check, 9 Mental Health and Lifestyle Survey, 10 and Pregnancy and Birth Survey (Figure 1 ). 11 , 12 The eligible population of the Basic Survey was mainly individuals registered as residents in Fukushima Prefecture between March 11 and July 1, 2011 (including evacuees) and residents of other prefectures who commute to Fukushima Prefecture, totaling approximately 2.05 million people.…”

“…The subjects of the baseline examination (1 st survey) on October 9, 2011 consisted of 367,637 residents, and the examinations were planned to be completed between 2011 and 2013, in order to check the pre-exposure status of the thyroid. 8 Follow-up examinations (2 nd survey) were conducted between 2014 and 2015, a 3 rd survey between 2016 and 2017, and a 4 th survey between 2018 and 2019. In addition, survey for adults administered every 5 years was initiated in 2016.…”

No increase in translocated chromosomal aberrations, an indicator of ionizing radiation exposure, in childhood thyroid cancer in Fukushima Prefecture

“…Therefore, primary examination of the Thyroid Ultrasound Examination (TUE) program conducted in FP in 2011-2013, and included 367,649 subjects (81.7% coverage)) who were generally ≤ 18 years old and living in FP at the time of the disaster. Conducting the TUE immediately after the GEJE enabled comparison of the obtained results with subsequent occurrence of thyroid cancer (5). Thereafter, primary examinations of TUE were conducted every two years until the examined individual was ≥ 20 years, with milestone examinations conducted every ve years thereafter.…”

Revisiting the Geographical Distribution of Thyroid Cancer Incidence in Fukushima Prefecture: Analysis of Data From the Second- and Third-round Thyroid Ultrasound Examination

“…To date, the results of the second- (fiscal years 2014–2015) and third- (fiscal years 2016–2017) rounds of the survey (Full-scale Survey) have been finalised. 11 Using the results of the second-round survey, two studies reported no statistically significant association between the estimated radiation dose and thyroid cancer diagnosis. 12 , 13 Some studies also indicated that the detection rates of thyroid cancer in the second-round survey were associated with the mean external radiation dose in air based on published regional counts of thyroid cancer cases, 14 , 15 although the results could not be adjusted for the age at diagnosis and prevalence and incidence could not be distinguished.…”