Detection of thyroid cancer among children and adolescents in Fukushima, Japan: a population-based cohort study of the Fukushima Health Management Survey

Hideto Takahashi; Seiji Yasumura; Kunihiko Takahashi; Tetsuya Ohira; Hiroki Shimura; Hitoshi Ohto; Satoru Suzuki; Shinichi Suzuki; Tetsuo Ishikawa; Satoshi Suzuki; Enbo Ma; Masanori Nagao; Susumu Yokoya; Kenji Kamiya

doi:10.1016/j.eclinm.2024.102722

Detection of thyroid cancer among children and adolescents in Fukushima, Japan: a population-based cohort study of the Fukushima Health Management Survey

EClinicalMedicine. 2024 Aug 26:75:102722. doi: 10.1016/j.eclinm.2024.102722. eCollection 2024 Sep.

Authors

Hideto Takahashi^{1

2}, Seiji Yasumura^{3

2}, Kunihiko Takahashi^{4

2}, Tetsuya Ohira^{5

2}, Hiroki Shimura^{6

2}, Hitoshi Ohto², Satoru Suzuki^{7

2}, Shinichi Suzuki^{8

9}, Tetsuo Ishikawa^{10

2}, Satoshi Suzuki^{7

2}, Enbo Ma^{11

5}, Masanori Nagao^{5

2}, Susumu Yokoya^{12

2}, Kenji Kamiya^{13

2}

Affiliations

¹ Teikyo Heisei University, Tokyo, Japan.
² Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University, Fukushima, Japan.
³ Department of Public Health, Fukushima Medical University School of Medicine, Fukushima, Japan.
⁴ Department of Biostatistics, M&D Data Science Center, Tokyo Medical and Dental University, Tokyo, Japan.
⁵ Department of Epidemiology, Fukushima Medical University School of Medicine, Fukushima, Japan.
⁶ Department of Laboratory Medicine, Fukushima Medical University School of Medicine, Fukushima, Japan.
⁷ Fukushima Global Medical Science Center, Fukushima Medical University, Fukushima, Japan.
⁸ Department of Surgery, Japan Community Healthcare Organization (JCHO), Nihonmatsu Hospital, Nihonmatsu, Japan.
⁹ Department of Thyroid and Endocrinology, Fukushima Medical University School of Medicine, Fukushima, Japan.
¹⁰ Department of Radiation Physics and Chemistry, Fukushima Medical University School of Medicine, Fukushima, Japan.
¹¹ Health Promotion Center, Fukushima Global Medical Science Center, Fukushima Medical University, Fukushima, Japan.
¹² Thyroid and Endocrine Center, Fukushima Medical University, Fukushima, Japan.
¹³ Radiation Effects Research Foundation, Hiroshima, Japan.

Abstract

Background: Thyroid ultrasound examinations using a cohort study design (from the Fukushima Health Management Survey [FHMS]) were conducted after the nuclear power plant accident caused by the Great East Japan Earthquake in 2011. This study investigated the association between radiation exposure and the detection of thyroid cancer in children and adolescents.

Methods: The cohort study has been conducted in Fukushima prefecture in Japan since 2011. The primary outcome was the external dose. We enrolled 253346 examinees who lived in Fukushima at the time of the accident (Dataset A), including 113120 examinees who had data on external radiation exposure (ERE) (Dataset B). The median dose in the examinee's district was used for missing dose. The association between ERE and detection of thyroid cancer or suspected thyroid cancer was analyzed using Poisson regressions with two types of explanatory variables: sex, age, overweight status, and district (Model 1), and past medical history, family history of thyroid cancer, frequency of seafood consumption, and frequency of seaweed consumption in addition to Model 1 (Model 2).

Findings: During the second and third rounds of examinations, a total of 97 thyroid patients were detected, for a detection rate of 10.328 [ $10^{5} {year}^{- 1}$ ] (95% confidence interval: 8.464-12.602 [ $10^{5} {year}^{- 1}$ ]). Multivariate Poisson regression showed that the detection rate ratio of the ERE (1+ mSv) to <1 (mSv) was 1.577 (0.715-3.394) in Model 1 and 1.596 (0.726-3.512) in Model 2, for Dataset A; and 1.677 (0.746-3.773) in Model 1 and 1.669 (0.743-3.748) in Model 2, for Dataset B.

Interpretation: Our study showed no association between radiation exposure with extremely low dose which were more than 99.9% of all the exposure was less than 5 mSv, and thyroid cancer detection, when the follow-up period was an average of 3.7 years at the present, using the cohort study design.

Funding: The National Health Fund for Children and Adults Affected by Nuclear Incidents in Japan.

Keywords: Cohort study; Detection rate; Full-scale thyroid (second- and third-round) examinations; Japan Fukushima Health Management Survey.