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Fukushima Thyroid Examination May 2015: 103 Thyroid Cancer Cases Confirmed, 5 in the Second Round Screening

The Nineteenth Prefectural Oversight Committee for Fukushima Health Management Survey convened in Fukushima City, Fukushima Prefecture, on May 18, 2015, releasing the latest results of thyroid examination, consisting of Initial Screening or the first round screening (originally scheduled to be conducted from October 2011 to March 2014, but actually still ongoing) and Full-Scale Screening or the second round screening (beginning April 2014). It has been 3 months since the last committee meeting on February 12, 2015, and the latest results include 3 more months worth of data confirmed as of March 31, 2015.

An official English translation of the results is now available here.

As of March 31, 2015, there are 16 more (12 from the first round and 4 from the second round) confirmed cancer cases, all papillary thyroid cancer, and 9 more (2 from the first round and 7 from the second round) newly suspicious cases. The number of confirmed cancer cases now totals 103 (98 from the first round and 5 from the second-round), and 23 more await surgical confirmation. (The number of suspicious/malignant is officially 127, including the single case of post-surgically confirmed benign nodules).

Initial Screening (the first round screening) targeted about 368,000 individuals who were age 18 and younger, residing in Fukushima Prefecture at the time of the Tokyo Electric Fukushima Daiichi nuclear power plant accident on March 11, 2011. 

Full-Scale Screening (the second round screening), to be conducted every 2 years until age 20 and every 5 years after age 20, additionally targets those who were born in the first year after the accident, aiming to examine approximately 385,000 individuals in a 2-year period. 

Officials are still accepting first-time subjects in the first round screening in an attempt to raise the participation rate, allowing those who haven't yet undergone Initial Screening to participate in it so long as they have not received a notification letter for Full-Scale Screening. As a result, 966 more, or 81.5% of the eligible underwent the primary ultrasound examination, either in Fukushima Prefecture or in other prefectures where they have relocated to. This is 0.3% more than the results released on February 12, 2015, and gave rise to the 2 newly suspicious cases. Although no individual information was released, a comparison of the latest results to the previous results from February 2015 reveals that they are both women, one from Iwaki City and the other from Aizu Wakamatsu City, whose ages were 11 and 18 at the time of the accident, and at least one of the two had a tumor diameter of 45.0 mm. 

The second round screening results include a table showing how the test results changed from the Initial Screening to the Full-Scale Screening. The column called "Non-participants" shows 7,072 subjects who never underwent the first-round screening but went through the second-round screening. It seems more logical to include the above 2 cases in the "Non-participants" category of the second-round screening, rather than in the first-round screening.

It is notable that the number of suspicious/malignant cases in the second-round screening nearly doubled, from 8 to 15, in the three months since the February report. The number of subjects participating in the confirmatory examination increased by about 60%, and the number of confirmed results nearly doubled with the number of biopsy increasing by 150%. So it is in a way not surprising the number of suspicious/malignant cases warranting surgical confirmation increased. Moreover, it is a concern that a little over half of those eligible for the confirmatory examination actually were examined, which means the number of suspicious/malignant cases are projected to increase even more as the progress rate of the confirmatory examination increases.

Again the details of the additional 7 cases newly determined to be suspicious/malignant after biopsy are not specified in detail, but comparison with the previous results reveals they include 2 males (ages 12 and 14 at the time of the accident) and 5 females (ages 8, 14, 17, 17 and 18 at the time of the accident). The average tumor diameter for the suspicious/confirmed cases in the second-round decreased slightly from 10.2 mm to 9.1 mm with the maximum diameter remaining the same, suggesting most newly diagnosed cases had tumor diameters on the smaller end. Their first round screening results include 3 cases each of A1 and A2, and a case of B. The places of their residence at the time of the accident include the FY 2011 target municipalities of Minamisoma City and Date City and the FY 2012 target municipalities of Fukushima City (4 cases) and Nihonmatsu City. According to the previous results (Jan 2012,  May 2012), most of the Minamisoma City residents had Initial Screening by the end of December 2011, and the Date City residents were screened in Jan-March 2012, whereas Initial Screening began in May 2012 in Fukushima City and in September 2012 in Nihonmatsu City. Although biopsy results were confirmed in these 7 cases sometime between January and March 2015, it is not clear exactly when they underwent the primary examination of the Full-Scale Screening which began in April 2014. Given the limited amount of information, it is not possible to identify where the previously A1 cases lived, who apparently had no ultrasound findings in Initial Screening. It means they likely developed the tumor in a little over 2 years since the last screening, and about 3 years after the accident. 

The Interim Summary of the Thyroid Examination Evaluation Subcommittee meeting, held on March 24, 2015, was reviewed during this committee meeting, as the Subcommittee meeting apparently wrapped up its session as of the March meeting at the end of FY 2014*. The Subcommittee came to a conclusion that the current situation where 99 of 112 suspicious/malignant cases had surgeries and 98 were confirmed with thyroid cancer (95 papillary thyroid cancer and 3 poorly differentiated cancer) clearly represents an excess incidence of pediatric thyroid cancer increased over the Japanese prevalence rate by an order of magnitude (At the November 11, 2014 subcommittee meeting, it was described as "61 times"). Amongst several issues addressed, the interim summary states that this increase can be a result of either excess occurrence due to radiation exposure or over-diagnosis, and that there were opinions amongst the subcommittee members that the current scientific knowledge does not completely deny the former, yet the latter was more likely. It goes on to state, "At the current time, it is not possible to conclude if thyroid cancer cases detected during the screening are radiation-induced. The results of the Initial Screening suggest that it is unlikely these cases are the effect of radiation exposure, considering that the exposure dose is far less than the Chernobyl accident and that there have been no cancer cases in children younger than 5 at the time of the accident. However, a long-term, ongoing study is needed in order to evaluate the effect of radiation exposure. Moreover, the early internal exposure dose from radioactive iodine is extremely critical in assessing the effect of the accident. The screening should continue in conjunction with the dose estimation study. "

Meanwhile, attendees and webcast viewers were surprised to find out that Shinichi Suzuki, a Fukushima Medical University thyroid surgeon who was in charge of the Fukushima Thyroid Examination was replaced with Akira Otsuru, an internist and a professor in the Department of Radiation Health Management at Fukushima Medical University. Otsuru, formerly of Nagasaki University, was one of the first to go to Fukushima Prefecture immediately after the accident as a head of the radiation medicine team sent from Nagasaki University. Otsuru was clearly not knowledgeable about surgical details of the cases as Suzuki was, although a lot of details were not released by Suzuki citing patient confidentiality anyway. During the committee meeting as well as the press conference afterwards, Otsuru often did not seem to comprehend questions from other committee members or journalists. There was already an issue of data management and transparency with Suzuki withholding some data from the committee, prioritizing presentations at academic meetings. With the assignment of Otsuru and absence of Suzuki at the committee, there appeared to be a setback of information disclosure and transparency.


A summary of results are provided below for Initial Screening and Full-Scale Screening, followed by unofficial translation of selective tables from the results. All numbers shown below are from the data analysis as of March 31, 2015.

Initial Screening (October 2011 - ongoing)

Total number targeted: 367,685

Number of participants in primary examination: 299,543
Number with confirmed results: 299,233
  • A1   154,018 (51.5%) (no nodules or cysts found)
  • A2   142,936 (47.8%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
  • B         2,278   (0.8%) (nodules ≧ 5.1 mm or cysts ≧ 20.1 mm)
  • C                1   (0.0%) (requiring immediate secondary examination)
(Note: Cysts with solid components are treated as nodules).

Number eligible for secondary examination: 2,279
Number of participants in confirmatory (secondary) examination: 2,096
Number with confirmed results : 2,034
Number of fine-needle aspiration cytology (FNAC): 529
Number suspicious or confirmed of malignancy: 112 (including one case of benign nodules)
Number with confirmed tissue diagnosis after surgery: 99
  • 1 benign nodule
  • 95 papillary thyroid cancer
  • 3 poorly differentiated cancer

Full-Scale Screening (April 2014 - March 2016)

Total number targeted: 220,000 in FY2014 (about 385,000 total)
Number of participants in primary examination: 148,027
Number with confirmed results: 121,997

  • A1   50,767 (41.6%) (no nodules or cysts found)
  • A2   70,187 (57.5%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
  • B       1,043   (0.9%) (nodules ≧ 5.1 mm or cysts ≧ 20.1 mm)
  • C              0   (0.0%) (requiring immediate secondary examination)
(Note: Cysts with solid components are treated as nodules).

Number eligible for secondary examination: 1,043
Number of participants in confirmatory examination: 593
Number with confirmed results: 491
Number of FNAB: 54
Number suspicious or confirmed of malignancy: 15
Number with confirmed tissue diagnosis after surgery: 5
  • 5 papillary thyroid cancer

Unofficial translation of selected tables

Initial Screening

Table 1. Primary examination coverage as of March 31, 2015

Table 2. Number and proportion of children with nodules/cysts as of March 31, 2015

Table 3. Confirmatory examination coverage and results as of March 31, 2015

Table 4. Cytology results (including information from Appendix 7: Surgical cases of suspicious or malignant cases)

Table 9. Primary and confirmatory examination results by municipality (Interim report)
Note 10: Excluding duplicates and unconfirmed results.
Note 11: Excluding unconfirmed results. 
Note 12: The number of FNAC, out of (c), including those who were reclassified as A1 or A2.
Note 13: Excluding one suspected case found benign after surgery.
Note 14: 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 15: 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 16: Iwaki City, Soma City, Shinchi Town
Note 17: 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

Full-Scale Screening

Table 1. Primary examination coverage as of March 31, 2015

Table 2. Number and proportion of children with nodules/cysts as of March 31, 2015

Table 3. Changes in the results of Initial Screening and Full-Scale Screening as of March 31, 2015

Table 4. Confirmatory examination coverage and results as of March 31, 2015

Table 5. Cytology results (including information from Appendix 6: Surgical cases of suspicious or malignant cases)


*Japanese governmental committees run on fiscal year schedules--April to March of the following year--and seem to be required to produce some sort of report, often called an "interim summary," which are essentially the final report. Although it wasn't clearly announced, it seemed to be understood during the March session that the Subcommittee would not meet again and the interim summary would be forwarded to the next session of its parent committee, the Prefectural Oversight Committee for Fukushima Health Management Survey). 


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Fukushima Thyroid Examination Fact Sheet: September 2017 (Long Version)

Fukushima Thyroid Examination Fact Sheet:  September 2017
✴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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