Status of Fukushima Children's Thyroid

[Summary : I would like to know the prevalence of thyroid nodules in children other than Fukushima which is based on the ultrasonography with resolution of 1mm. I would appreciate if anyone could present such data.]

Fukushima Prefecture has been conducting health examination of their children under 18 years old. On September 11, 2012, the Radiation Medical Science Center for the Fukushima health management survey, Fukushima Medical University has published the 8th (2012) report of the first thyroid examination of the second group.

http://fukushima-mimamori.jp/thyroid/media/thyroid_status_201209.pdf

The detailed translation of the report is here (but please note that “nodule” is meant for “solid nodule” except cyst in the translation:
FukushimaVoice: Fukushima Thyroid Examination Part 2
http://fukushimavoice-eng.blogspot.jp/2012/09/fukushima-thyroid-examination-part-2.html

In total of 42,060 children of the second group analyzed, the nodules were diagnosed by ultrasonography with the resolution of 1mm as below.

Solid nodule (A2 criterion) ≦ 5.0mm : 153 (0.37%)
Solid nodule (B criterion) ≧ 5.1mm : 232 (0.55%)
Cyst (A2 criterion) ≦ 20.0mm: 18,136 (43.12%)
Cyst (B criterion) ≧ 20.1mm : 3 (0.007%)

The children of A2 criterion are not basically to take the second examination during next two years and the children of B criterion are to take the second examination relatively soon.

Among 186 diagnosed as B criterion from 38,114 in the 2011 first examination of the first group, one has already been diagnosed as having thyroid cancer in the second examination.

According to the article below, the prevalence of thyroid nodules in children is up to 3% by ultrasound scan. I wonder the prevalence of 43.12% in Fukushima children can be compared with 3% of the article as the resolution for the latter is unclear.

Management of Thyroid Nodules in Children
http://www.eurospe.org/clinical/CPC%20Docs/ManagementOfThyroidNodulesInChildren.pdf

The Fukushima Health Examination is led by Dr.Shunichi Yamashita, Vice Chancellor of Fukushima Medical University. The University is not willing to open the raw echo images even to the subjects, saying “the images can be falsified”.

http://mainichi.jp/select/news/20120826k0000e040108000c.html

Dr.Yamashita has responsibility to explain the implication of the examination results based on the past data, but does not.

Urinary Iodine Levels and Thyroid Diseases in Children; Comparison between Nagasaki and Chernobyl
https://www.jstage.jst.go.jp/article/endocrj1993/48/5/48_5_591/_pdf

Dr.Yamashita wrote in the above paper:

“Comparison of thyroid abnormalities between Gomel, Belarus (n=19,660) and Nagasaki (n=250), detected by the ultrasound screening.”
“Nodules more than 5 mm in diameter were considered to be "positive".”
“In Nagasaki, only four cases showed goiter (1.6%) and two cases (0.8%) had cystic degeneration and single thyroid cyst. There was no evidence of thyroid nodule detected by US examination.”

In Japan, the term “nodule” is used for the meaning of “solid nodule”.

As the Nagasaki subjects are not sufficient and the measuring criterion of cyst is not described, we can not reliably compare Fukushima and Nagasaki.

So I would like to know the prevalence of thyroid nodules in children other than Fukushima which is based on the ultrasonography with resolution of 1mm. I would appreciate if anyone could present such data.

Mitsumasa Ohta
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