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First Round of Fukushima Thyroid Examination Complete: Provisional Results Show 57 Confirmed and 46 Suspected Cases of Thyroid Cancer, A Total of 103 Cases.

Sixteenth Prefectural Oversight Committee for Fukushima Health Survey convened on August 24, 2014, releasing the latest results of the thyroid examination, consisting of the near-complete results of the preliminary examination over the last three years, intended to obtain a baseline, as well as the partial results from the regular examination, which will keep track of any changes.

Official English translation of the results are available here.


The initial round of thyroid examination, the preliminary examination, finished as of March 31, 2014. Although not all the examinations have been completed, the provisional results, as of June 30, 2014, were released.The second round of thyroid examination, the regular examination, testing everyone again beginning with areas exposed to higher radiation doses, has already begun.


A summary of the results of the preliminary examination is provided below:


Total number of children examined as of June 30, 2014: 296,026

Total number of children whose initial examination results are confirmed: 295,689
   
     Assessment A1  152,389 (51.5%) (no nodules or cysts found)
     Assessment A2  141,063 (47.7%) (nodules 5.0 mm or smaller or cysts 20.0 mm or smaller)
     Assessment B     2,236 (0.8%) (nodules 5.1 mm or larger or cysts 20.1 mm or larger)
     Assessment C         1 (0.0%) (requiring immediate secondary examination)


Translation of some tables from the results of thyroid preliminary examination:



Page 3

Initial examination progress status



Number and proportion of nodules and cysts


Secondary examination includes more detailed thyroid ultrasound, blood and urine tests, and fine-needle aspiration biopsy if warranted.
      2,237 are eligible for secondary examination
      1,951 have actually undergone secondary examination
      1,848 finished the secondary examination


Page 4

Secondary examination progress status


Pages 5-6
2  Summary of fine-needle aspiration biopsy results
(1) Results of biopsy (as of June 30, 2014)


(2) Regarding indications for surgery

In Japan, when thyroid cancer is suspected, absolute indications for surgery include pre-surgical tumor with a diameter equal to or greater than 10 mm, lymph node metastases, extrathyroidal extension, and distant metastases. Furthermore, tumors with a diameter of 10 mm or smaller, so-called microcarcinomas, might be followed with observation in adults. However, surgery might be indicated for microcarcinomas if they are accompanied by lymph node metastasis, distant metastasis or extrathyroidal spread, or in close proximity to the recurrent laryngeal nerve or the trachea. 

In our thyroid examination, participants who are found to be in the B or C assessment category during the primary examination go onto the secondary examination. Biopsy is recommended based on the findings of the repeat ultrasound examination. If the biopsy shows confirmed or suspected malignancy, they will be treated according to the above indication criteria, with adequate informed consent. 

In addition, treatment guideline mentioned above has been discussed at the Diagnostic Criteria Assessment Subcommittee of the Thyroid Examination Expert Committee, consisting of specialists from related specialty societies.

References: 
Thyroid Ultrasound Diagnostic Guidebook 2010 (Edited by Japan Association of Endocrine Surgeons and Japan Society of Thyroid Surgery)
Thyroid Ultrasound Diagnostic Guidebook, revised, 2nd edition (Edited by The Japan Association of Breast and Thyroid Sonology and Thyroid Terminology and Diagnostic Criteria Committee)
Thyroid Nodule Treatment Clinical Guidelines 2013 (Edited by Japan Thyroid Association)

***

Commentary by the writer/translator: 

In summary, there were 14 more cancer cases, 4 boys and 10 girls, confirmed since the last report on May 19, 2014. All 14 cases came from the FY2013 targeted municipalities, where the secondary examination is still ongoing. 

The total number of cases confirmed or suspected of cancer is 104. Of these, 59 had surgeries as of June 30, 2014 and 1 turned out to be a benign nodule, 55 were confirmed to be papillary thyroid cancer, and 2 were confirmed as poorly differentiated thyroid cancer. Additionally, 46 were "suspected" of having thyroid cancer. (The total number of cases confirmed or suspected of cancer is often reported as 103 in news reports, excluding the case confirmed to be benign). 

In the Asahi Shimbun article, released in the morning of August 24, 2014 and contained apparently leaked information, Fukushima Medical University was quoted as saying it was unlikely that these cancer cases were related to radiation exposure.

Although the data is incomplete as the results from the Aizu area, part of the FY2013 municipalities, are not all available, a table was provided for regional comparison.


Page 10
Table 9: Proportions of subjects in B&C assessment categories as well as confirmed/suspected of malignancy (provisional)


Note 10: Excluding duplicate data and unconfirmed results
Note 11: The number of participants whose fine-needle aspiration biopsy results, done before June 30, are confirmed.  
Note 12: Excluding one case that was suspected of malignancy but turned out to be benign after surgery
Note 13: Tamura City, Minamisoma City, Date City, Kawamata Town, Hirono Town, Naraha Town, Tomioka Town, Kawauchi Village, Okuma Town, Futaba Town, Namie Town, Katsurao Village and Iitate Village
Note 14: Fukushima City, Koriyama city, Shirakawa City, Sukagawa City, Nihonmatsu City, Motomiya City, Koori Town, Kunimi Town, Otamamura Village, Kagamiishi Town, Tenei Village, Nishigou Village, Izumizaki Village, Nakajima Village, Yabuki Town, Tanagura Town, Yamatsuri Town, Hanawa Town, Samegawa Village, Ishikawa Town, Tamakawa Village, Hirata Village, Asakawa Town, Furudono Town, Miharu Town, and Ono Town
Note 15: Iwaki City, Soma City, Shinchi Town
Note 16: Aizuwakamatsu City, Kitakata City, Shimogo Town, Hinoemata Village, Tadami Town, Minamiaizu Town, Kitashiobara Village, Nishiaizu Town, Bandai Town, Inawashiro Town, Aizubange Town, Yugawa Village, Yanaizu Town, Mishima Town, Showa Village, and Aizumisato Town

〈Results and Discussion of regional comparison〉


 A regional analysis was conducted of 295,689 participants who underwent the primary examination, excluding those who were confirmed to be duplicate entries and those whose results have not been finalized.

The result of the analysis revealed the rate of assessment categories B & C tended to increase in the order of “13 municipalities including the evacuation zone,” “Nakadori,” “Hamadori.” and Aizu Region.

On the other hand, the rate of of those “confirmed or suspected of malignancy” was almost the same in “13 municipalities including the evacuation zone,” “Nakadori,” and “Hamadori,” and slightly lower in “Aizu region.” This could be due to the fact that Aizu region has a lower proportion of secondary examination participants who actually completed it.

(End of page 10)


***

Commentary by the writer/translator: 


As a reference to grasp the geographical relationship of these regions, the map below, excerpted from the August 25, 2014 Fukushima Minyu article, color-codes the above comparison regions.
          Red: 13 municipalities including the evacuation zone
          Blue: Nakadori
          Yellow: Hamadori
          Green: Aizu region

                                                                           (Source)

However, this particular grouping of municipalities to form comparison regions is drawing some criticisms as it may not be a good reflection of how the radioactive plume spread. For instance, Hamadori as defined here, which is not exactly the same as the conventional Hamadori, clumps Iwaki City where the highly radioactive plume hit, together with two municipalities up north on the Fukushima-Miyagi border, which did not receive as much plume. Also, a municipality might not be uniformly contaminated depending on its topography.

***

As for the partial results of the regular examination (the second round of examination), 28,575 have gone through the primary examination from the 2014 targeted municipalities, out of 213,223 eligible, and results have been determined for 6,458 of them. There were 46 in the B assessment category, but it was unclear if all of these individuals were also in the B category in the preliminary examination, or if any of these cases are newly diagnosed.




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✴Copying or re-posting part or whole of this post is not permitted. Please link to this post instead.

Note: Corrections were made in the following paragraphs in pink color on October 17, 2017.
Second paragraph in section "Screening protocol"
First paragraph in section "Thyroid cancer cases"
First paragraph in section "Transparency and integrity of data"
Second paragraph in subsection "1. A limited time interval after the accident" in section "Official stance on radiation effects"
Fourth paragraph in subsection "2. Very low doses" in section "Official stance on radiation effects"

Note: A shorter version of this fact sheet has been e-published on the website of Kagaku by the Iwanami Publishers. It can be downloaded from this link. Citation in AMA style is as follows: Hiranuma Y. Fukushima thyroid examination fact sheet: September 2017. Kagaku. 2017;87(9):e0001-e0011.


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