Fukushima Thyroid Examination May-June 2020: 195 Surgically Confirmed as Thyroid Cancer Among 241 Cytology Suspected Cases

 

Highlights 

     In May and June 2020, two sessions were held within 3 weeks of each other, releasing the thyroid cancer data. Due to the COVID-19 pandemic, both sessions were held in a web conference format. First was the 38th session of the Oversight Committee held on May 25, 2020. Then on June 15, 2020, the 15th session of the Thyroid Ultrasound Examination Evaluation Subcommittee (TUE Subcommittee) convened, updating some of the data released 3 weeks earlier. 

   This post will cover the June 15 data, which is inclusive of the May 25 data, and the development since the last session of the Oversight Committee on February 13, 2020.

• The third round: 1 case newly diagnosed as suspicious or malignant, and 1 new cases surgically confirmed. Final report released on June 15, 20.
• The fourth round: No new cases diagnosed as suspicious or malignant, and 3 new surgical cases. 
• Age 25 Milestone Screening: 3 cases newly diagnosed as suspicious or malignant, and 3 new surgical cases. 
• Total number of suspected/confirmed thyroid cancer has increased by 4 to 240 excluding a single case of benign tumor: 115 in the first round, 71 in the second round, 31 in the third round, 16 in the fourth round, and 7 in Age 25 Milestone Screening.
• Total number of surgically confirmed thyroid cancer cases has increased by 9 to 195 (101 in the first round, 52 in the second round, 27 in the third round, 11 in the fourth round, and 4 in Age 25 Milestone Screening)

• Data reported is as of December 31, 2019 for the fourth round and March 31, 2020 (the end of Fiscal Year 2019) for the third round and the Age 25 Milestone Screening. (Reporting this year has been delayed in general due to the December 2019 session never being held.)
• A list of official English translation of the results has finally been updated on the new website for the Radiation Medical Science Center of the Fukushima Health Management Survey. It now includes the three 2019 sessions up to the 36th Oversight Committee held on October 2019. (There were only three sessions in 2019.) The catch is, the agenda materials are only downloadable as one large file per session, so it takes a bit of time to look for the TUE results. Unfortunately, the old website which used to show individual reports for each session no longer exists, and the URLs for translations in the previous posts are no longer valid. Time permitting, those URLs will be updated.

The latest overall results including the "unreported" cases

(See this post for description of the "unreported" cases. Histological diagnosis of the 11 unreported cancer cases was obtained from this paper.)

Overview

     On May 25, 2020, the 38th session of the Oversight Committee for the Fukushima Health Management Survey (FHMS) convened in Fukushima City, Fukushima Prefecture to release the third- and fourth-round data as of December 31, 2019. Then, merely 3 weeks later, the 15th session of the Thyroid Ultrasound Examination (TUE) Evaluation Subcommittee ("TUE Subcommittee") was held on June 15, 2020, this time releasing the final version of the third-round results as well as the results of the Age 25 Milestone Screening, both as of March 31, 2020, which is the end of the Fiscal Year 2019.

    The fourth-round results is anticipated to be updated to data as of March 31, 2020 at the 39th session of the Oversight Committee scheduled for August 31, 2020. 

    The screening has slowed down due to the COVID-19 pandemic. In particular, temporary school closures from March through May interrupted the TUE conducted in school settings, which accounts for a big chunk of the data. Most affected by this slow down would be the fourth-round results, and the next set of data as of March 31 might begin to reflect it.

    
    It is expected that the official English translation will eventually become available on the website of the Radiation Medical Science Center for the Fukushima Health Management Survey. This website has finally been updated with the official English translation of the excerpted agenda materials from the three 2019 Oversight Committee sessions.

Summary on the current status of the TUE

     A six-page summary of the first through fourth rounds as well as the Age 25 Milestone Screening, "The Status of the Thyroid Ultrasound Examination," lists key findings from the primary and confirmatory examinations as well as the surgical information. 

     In the past, the same version released at the Oversight Committee session was distributed at the subsequent TUE Subcommittee. However, this time, the version released at the May 25th Oversight Committee session was updated for the June 15th TUE Subcommittee session. Here, the more updated and complete June 15th version is unofficially translated. (There is no official translation of this summary.)

#38 Status of the Thyroid Ultrasound Examination by Yuri Hiranuma

The third round
   The final report of the third-round results was released at the June 15th TUE Subcommittee. It includes fiscal year-end data as of March 31, 2020. Any further supplemental information, such as an additional surgical cases, is expected to be released at the end of the next fiscal year.

   Curiously, when the third-round data as of December 31, 2019 was released at the Mary 25 Oversight Committee session, Hiroki Shimura, director of the TUE, stated that he did not have the final report yet because the confirmatory examination was still progressing. Then 3 weeks later the results were finalized. Perhaps the confirmatory examination was indeed concluded after May 25, but regardless it seems that the intention was to release the final report at the TUE Subcommittee which is tasked with analyzing the third-round data.

  One significant drawback of the final report being released to the TUE Subcommittee is that it will not be officially translated into English. This is what happened to the final report of the second round, including the FY 2017 supplementary version of the final report of the second round, released at the 31st Oversight Committee session on June 18, 2018. (Note: The final report was actually released at the 39th session of the Oversight Committee on August 31, 2020. It remains to be seen if an official translation materializes.)

  Between October 1, 2019 and March 31, 2020, 17 more participated in the primary examination. The final participation rate remained at 64.7%. Three took part in the confirmatory examination, and four underwent fine-needle aspiration cytology (FNAC) which detected one new case of suspected thyroid cancer in a 12-year-old male (age 5 at the time of the 2011 nuclear accident) from the 13 evacuated municipalities. His previous result from the second round was A1, meaning he had no detectible lesion on ultrasound.

  The number of suspected or confirmed thyroid cancer cases from the third round increased by 1 to 31. The previous results from the second round are as follows: 21 with "A" (7 with A1, 10 with A2 cysts, and 4 with A2 nodules), 7 with "B," and 3 with no prior screening.

   With an addition of 3 new surgical cases (1 from the FY 2016 municipalities and 2 from the FY 2017 municipalities),  a total of 27 thyroid cancer cases, all papillary thyroid cancer, were surgically confirmed in the third round.

Regional analysis

   Customary with the first two rounds, the final report of the third round includes a table showing proportions of B/C test results and suspicious/malignant cases by region.

   Attention was focused on why Nakadori's cancer rate per 100,000 is so much lower than other 3 regions at 6.6. No clear explanation was given.

The fourth round
   The fourth round, scheduled from April 1, 2018 through March 31, 2020, is still ongoing. Between September 30, 2019 and December 31, 2019, the primary examination gained 26,511 more participants, raising the current participation rate to 55.6%, up from 46.5%. This is still below what the prior rounds registered: 81.7% for the first round, 71.0% for the second round, and 64.7% for the third round.

   Having received the "B" assessment in the primary examination, 255 became eligible for the confirmatory examination and 120 newly participated. The participation rate actually dipped slightly from 59.8% to 55.7%. Out of five participants that underwent FNAC, none was diagnosed with suspected cancer. 

   The number of suspected or confirmed thyroid cancer cases from the fourth round remained unchanged at 16. The previous results from the third round also remain the same: 13 with "A" (3 with A1, 8 with A2 cysts, and 2 with A2 nodules) and 3 with "B." 

   With an addition of 3 new surgical cases (all from the FY 2018 municipalities),  a total of 11 thyroid cancer cases, all papillary thyroid cancer, were surgically confirmed in the fourth round.

Age 25 Milestone Screening
    In the Age 25 Milestone Screening, each screening year targets a cohort turning 25 during each fiscal year, and the results are reported every 6 months. The very first results as of March 31, 2018 (reported to the 31st session of the Oversight Committee) were included in the fourth-round results and can be accessed here (pages 31-32). Implementation schedule from the first full report as of September 30, 2018 (reported to the 33rd session of the Oversight Committee; pages 37-43 in this PDF)  is shown below.

 

   In April 2017, 22,633 individuals born in FY 1992 (the FY 1992 cohort) kicked off the Age 25 Milestone Screening, which notably reduces the size of target population for the main TUE. This reduction began in the third round conducted during FY 2016-2017, which excluded the FY 1992 and 1993 cohorts in anticipation of an upcoming Age 25 Milestone Screening. With each FY birth cohort including about 22,000 individuals, this is a sizable reduction which continues as the TUE target population ages. For example, the target population has gone from 367,637 for the first round, to 381, 244 for the second round (increased because those who were in utero at the time of the accident were included),  336,670 for the third round, and 294,213 for the fourth round.

   A fiscal year-end report for FY 2019 (link), which includes data as of March 31, 2020, adds data from 22,096 in the FY 1994 cohort. It also includes some updates on the FY 1992 and 1993 cohorts.  (Note: Although each fiscal year screening is earmarked for those turning 25 during that fiscal year, participants can take part in the screening anytime up to the year before they become eligible for the Age 30 Milestone Screening. As such, the report can include updated data from all fiscal year cohorts.)

   On a side note, the fact that the Age 25 Milestone Screening results were reported to the TUE Subcommittee means that it may never be officially translated, just like the final reports of the second and third rounds as explained above. That is, unless the results are also reported to the next Oversight Committee meeting scheduled for August 31, 2020. (Note: The results were also reported to the 39th session of the Oversight Committee on August 31, 2020.)

   Since October 1, 2019, 1,301 participants newly underwent the primary examination, including 16 born in FY 1992, 63 in FY 1993, and 1,222 in FY 1994. An overall participation rate actually decreased from 9.6% to 8.4% due to a larger denominator from an addition of the FY 1994 cohort. A participation rate for the FY 1994 is 5.5%. It remained at 9.9% for the FY 1992 cohort and increased by 0.3% to 9.6% for the FY 1993 cohort. Because the participation is not limited to a specific screening year as explained earlier, it is likely that the FY 1994 cohort will eventually have a higher participation rate. A fiscal year-end participation rate for the FY 1993 cohort as of March 31, 20019 was 4.5%, which has now more than doubled a year later. Still, these participation rates are conspicuously much lower than the main TUE.

   Eligibility for the confirmatory examination (a.k.a. "B" assessment in the primary examination) was gained for 46 more participants. Of 244 needing the confirmatory examination, 23 newly participated, and 3 newly underwent FNAC. All three, all females, were diagnosed with suspected thyroid cancer, and one had "B" in the previous screening whereas 2 never participated in the TUE.

  Thus the number of suspected or confirmed thyroid cancer cases from the Age 25 Milestone Screening increased by 3 to 7. The results from the prior screening are as follows: 1 with A2 (unclear if cyst or nodule due to lack of reporting), 1 with "B," and 5 with no prior screening.

   With an addition of 3 new surgical cases,  a total of 4 thyroid cancer cases, 2 papillary thyroid cancers and 1 follicular thyroid cancer, were surgically confirmed in the Age 25 Milestone Screening.

   The average tumor diameter from the FNAC was 22.6 ± 15.6 mm (range 10.8 - 49.9 mm). Note that this is a drastic jump from what was reported last time, 14.5 ± 2.7mm (range 12.3 - 18.0 mm), with the average diameter increasing by a factor of 1.5 and the maximum diameter nearly tripling. This is likely due to a single case of follicular thyroid cancer. 

Summary of the results from the previous screening 
     Below is the summary of the previous screening results for the suspected/confirmed thyroid cancer cases. This information, already mentioned above except for the second round, can be difficult to locate in print. In particular, a breakdown of the "A2" assessment is only verbally reported during the Oversight Committee sessions. 

Definition

"A1": no ultrasound findings. 

"A2": ultrasound findings of nodules ≤ 5.0 mm and/or cysts ≤ 20.0 mm. 

"B": ultrasound findings of nodules ≥ 5.1 mm and/or cysts ≥ 20.1 mm.

   Having previous assessments of "A1" or "A2 cysts" means there were no precancerous lesions during the previous screening, i.e., cancer supposedly appeared since the previous screening. (Note: FMU claims the cancerous lesions were simply "invisible" during the previous screening.)

• Second round (71 cases): 33 cases with A1, 32 cases with A2 (7 nodules and 25 cysts), 5 cases with B, 1 case previously unexamined
• Third round (31 cases):  7 cases with A1, 14 cases with A2 (4 nodules and 10 cysts), 7 cases with B, 3 cases previously unexamined
• Fourth round (16 cases): 3 cases with A1, 10 cases with A2 (2 nodules and 8 cysts), 3 cases with B
• Age 25 Milestone Screening (7 cases): 1 case with A2 (it was never reported if nodule or cyst), 1 case with B, 5 cases previously unexamined

The analysis and paper using the UNSCEAR doses 

   There was a development during the TUE Subcommittee that warrants a mention. It was as simple as a release of supplementary data and a report of a published paper, but it requires some background information for context, as explained below.

A belated release of the supplementary data 

   During the 15th session of the TUE Subcommittee, previously undisclosed supplementary data was released. It relates to "Document 1-2" reported to the 13th TUE Subcommittee held on June 3, 2019. (An unofficial translation of Document 1-2 can be found in this post.)

   Document 1-2, titled "Associations between absorbed doses to the thyroid by municipality estimated by UNSCEAR and detection rates of confirmed or suspected cancer," was one of the three documents released by Fukushima Medical University (FMU) that led the TUE Subcommittee to conclude (not unanimously), "Thus, at this time, no association is seen between thyroid cancer detected in the second round and radiation exposure." 

(*UNSCEAR is the United Nations Scientific Committee on the Effects of Atomic Radiation.) 

   It shows an analysis in which the second-round participants ≥ age 6 are divided into four groups based on four dose ranges according to the thyroid absorbed doses by municipality estimated in the UNSCEAR 2013 report. This involves grouping Fukushima Prefecture's 59 municipalities into 4 dose ranges based on the UNSCEAR absorbed thyroid doses. 

   An ideal dose-response analysis would be based on individual doses, but without sufficient individual dose data (only 1080 out of over 360,000 children in Fukushima had their thyroid doses directly measured after the accident), FMU was directed by none other than Subcommittee Chair Gen Suzuki to use "the best officially available doses" as a surrogate. 

   However, reliability of the UNSCEAR estimation itself is in question, potentially amplifying uncertainties inherent in the results from a regional dose-response analysis. Furthermore, throughout the Subcommittee sessions, members Tomotaka Sobue of Osaka University and Kota Katanoda of National Cancer Center cautioned that the use of regional doses could create unsolvable biases and the results could be difficult to interpret. 

   Yet such a dose-response analysis in evaluating the second-round results was encouraged by Subcommittee Chair Suzuki who was tasked with advancing the analysis. (Suzuki himself leads a research team reconstructing the doses and reported on a paper published by his team, which effectively reduced the estimated thyroid doses. This is not at all surprising given Suzuki's track record as a government-patronized researcher who is known to have successfully denied radiation effects multiple times in the past.)

   The aforementioned conclusion of the TUE Subcommittee, "no association is seen between thyroid cancer detected in the second round and radiation exposure," was not reached un-opposed. Some of the subcommittee members, including even Subcommittee Chair Suzuki, repeatedly requested FMU to provide actual numerical data in the analyses submitted throughout the Subcommittee sessions, so that they could fully grasp how FMU was "adjusting" the various data. This request was never fulfilled, and all that the Subcommittee members could do was take whatever came out of FMU at face value. 

   Eventually a draft summary prepared by Suzuki was hastily presented at the 13th TUE Subcommittee, in June 2019, which was the final session of the previous term of the TUE Subcommittee. This was also when Document 1-2 was first presented to the Subcommittee, which meant that there was hardly any time for the Subcommittee members to discuss the analysis in detail before the draft summary was prepared. Background information surrounding the controversial draft summary (unofficial translation here) is covered in this post. 

   Upon initial presentation, Document 1-2 lacked the numbers of subjects for each dose range, preventing a full understanding of the analysis by the Subcommittee members. Apparently this was intentional on the part of FMU: Ohira later admitted that the decision to withhold some numerical data was made by Subcommittee Chair Suzuki for fear of "misinterpretation." 

   Suzuki later explained that releasing the provisional data to the Subcommittee might mean high transparency to some, but such release might compromise originality of the data and actually prevent the data from being published in academic journals, because no peer-reviewed journals would accept a manuscript lacking originality. If that were to happen, the data would not be shared with the academic community, and that is what Suzuki was afraid of. 

   However, withholding the data from the Subcommittee members who are tasked with evaluating the data is flatly pointless. How can the Subcommittee conduct proper evaluation? (It couldn't.) Further, reading between lines, what Suzuki was probably insinuating was that they wanted to prevent a third party analysis and publication of the data before FMU published it. 

   In the past, Suzuki has blurted out that FMU was hesitant on releasing too much data because "some journal would conduct an independent analysis and come to a different conclusion." No specific journal was named, but it is presumed that he was referring to a Japanese science journal Kagaku by Iwanami Publishers, which at the time had been publishing a series of critical analyses by Junichiro Makino on FMU's data, including previous analyses led by Ohira on regional differences (i.e. dose-response) of thyroid cancer detection.

   Suzuki reasoned that it would be best for Ohira to publish his analysis in an academic journal as soon as possible, and the data can be released to the Subcommittee at a later data. That is exactly what happened here. With the analysis safely published, Document 1-2, finally (and belatedly) complete with the numbers of subjects for each dose range, was released again (link to PDF in Japanese). 

Problems with the published paper

   The paper, for which Ohira is a corresponding author, was published in the February 2020 issue of the Journal of Radiation Research, an official journal of the Japanese Radiation Research Society (JRRS) and the Japanese Society for Radiation Oncology (JASTRO) (link to the paper). 

*Incidentally, JRRS is the organization that originally recommended Gen Suzuki to become a member of the TUE Subcommittee in 2017. JRRS was also commissioned by the Ministry of the Environment to create official Japanese translation of the reports by the International Agency Research on Cancer (IARC)  international expert group on Thyroid Monitoring after Nuclear Accidents (TM-NUC). (See this post for details on TM-NUC.)

   After Ohira presented a summary of the paper in Japanese, Sobue called out an issue that the paper did not exactly follow the same method of the original analysis as in Document 1-2. Sobue demanded to know how the two—the paper and Document 1-2—were related. 

   Ohira explained that Document 2-1 included all participants ≥ age 6 in the second-round screening, regardless of whether they participated in the first round or what their first-round results were. Participants who were 5 years of age or younger were excluded because there was only 1 case of thyroid cancer (age 5) in that age group. 

     On the other hand, the paper included subjects ≥ age 6 who participated in both of the first- and second-round screenings, excluding those who were diagnosed with thyroid cancer in the first round. This is because the paper was written in accordance with the original design of the TUE which defined the first round as a baseline screening and any subsequent screenings as follow-ups. 

   As such, the total number of the subjects differed between Document 1-2 and the paper. Although they both included the TUE participants who were age 6 or older, Document 1-2 included 175,268 subjects (calculated by this author thanks to the newly released information), whereas the paper covered 164,299 subjects, 7% less than included in Document 1-2.

   This did not sit well with Sobue. It turns out that he and Katanoda, unbeknownst to them, were named in Acknowledgments "for their valuable advice on the manuscript." Both Sobue and Katanoda appeared astounded, not realizing that they were included in Acknowledgements until the day of the TUE Subcommittee session. Sobue exasperatedly stated that he wished he had been notified of any changes in the analytical methods before his name was included. 

   Ohira's reply was incredulous: Because Sobue and Katanoda had been advising FMU on using the thyroid absorbed doses estimated by UNSCEAR in the analysis, it was assumed that they would approve any similar analysis by extension and thus they were mentioned in Acknowledgements.

   This seems to be an utterly convenient assumption and a disregard for what is surely a standard scientific protocol on multiple fronts. Flatly, lack of common courtesy is appalling. In fact, Katanota had to explain that the current guidelines of the publishing ethics dictate that anyone whose name is included as having contributed to the manuscript, including Acknowledgements, should have been notified for reviewing the manuscript. 

   Even Subcommittee Chair Suzuki, who "approved" withholding the release of data until after the analysis is published, was at a loss for words on Ohira's reply. Ultimately Suzuki said that the Subcommittee members and the audience had a general idea of who the subjects were in Document 1-2, but altering the data for publication essentially means such alteration can be conducted at FMU's discretion. 

   Truly, that was the pattern seen throughout the Subcommittee sessions. Without complete data, no fair discussion can ensue. It's as if it doesn't even matter what is discussed in the TUE Subcommittee or even at the Oversight Committee. By now, those of us who have been following Fukushima's thyroid cancer saga are well aware that these committee and subcommittee sessions are just a charade. We knew this the minute Suzuki was selected to chair the TUE Subcommittee 3 years ago, as described in this post.

　During this Subcommittee session, Ohira also presented a cross-sectional analysis using the UNSCEAR estimated thyroid doses. Any further analysis based on a flawed assumption only propagates FMU's biased conclusion, especially with various adjustments conducted at their discretion. Refusing to contribute to such propagation, this blog will no longer offer unofficial translation of their biased analyses. 

   Rest assured, basic information on the original TUE data and other pertinent developments will continue to be offered as before.

Addendum (Note: this is by no means an endorsement but meant as record-keeping)

   A former member of the Oversight Committee and the TUE Subcommittee, Toru Takano, apparently spearheaded formation of a group called "Japan Consortium for Juvenile Thyroid Cancer." It's website, accessed here, is located on the website of Graduate School of Medicine and Faculty of Medicine at Osaka University. 

   This group's member roster includes those who were aggressively claiming that Fukushima's thyroid cancer was due to overdiagnosis: Akira Otsuru, Tomotaka Sobue, Toru Takano, Shoichiro Tsugane, and Sanae Midorikawa.

   It's astonishing that even current members of the Subcommittee (Sobue) and the Oversight Committee (Tsugane) are part of this group. Notably, Ohtsuru, Takano and Midorikawa have been vocally against the school-based screening. (Midorikawa was actually in charge of the school screening, but she is no longer with FMU.) With the COVID-19 pandemic slowing down the screening process, it is feared that this group might push towards ending the school screening or even the TUE itself.

   Objectives of the group might not be totally obvious from the website. Their beliefs and claims are explained by Midorikawa on the website of her new work place, Miyagi Gakuin Women's University (link). Excerpts are translated below:

• It is not that radiation exposure led to an increase in thyroid cancer in Fukushima.
• Many thyroid cancers happen to be "discovered" because of the Thyroid Ultrasound Examination (TUE).
• Further, majority of those thyroid cancer cases would not have been diagnosed if it weren't for the TUE: They are harmless cancers which probably would have remained undetected for life. (This is called overdiagnosis.)
• Even Fukushima residents and their families are unaware of this fact, and they continue to participate in the TUE.