Overview
On December 2, 2022, the 46th session of the Oversight Committee for the Fukushima Health Management Survey (FHMS) convened online and in Fukushima City, releasing a new set of results (data up to June 30, 2022) from the fourth and fifth rounds of the Thyroid Ultrasound Examination (TUE). It amounts to 3-month worth of data since the previous session held on September 1, 2022 (see previous post).
Official English translation (link) is available up to the 42nd session (PDF link) of the Oversight Committee on this page of the website of the Radiation Medical Science Center of the Fukushima Health Management Survey (RMSC/FHMS). This website also shows an outline of the FHMS and TUE itself.
Highlights
- The fourth round: no change. The final report could be imminent.
- The fifth round: 12 new cases diagnosed as suspicious or malignant, and 1 new surgical case.
- Total number of suspected/confirmed thyroid cancer has increased by 12 to 296: 116 in the first round (including a single case of benign tumor), 71 in the second round, 31 in the third round, 39 in the fourth round, 23 in the fifth round, and 16 in Age 25 Milestone Screening.
- Total number of surgically confirmed thyroid cancer cases has increased by 1 to 237 (101 in the first round, 56 in the second round, 29 in the third round, 34 in the fourth round, 7 in the fifth round, and 10 in Age 25 Milestone Screening,
The latest overall results including the "unreported" and cancer registry cases
Please refer to the the post on May 2021 report regarding the details of "unreported" cases and cancer registry data. (A July 2018 post describes the origin of the first 11"unreported" cases, and their histological diagnoses were obtained from this paper.)
The official count, as reported above and also in the summary document shown in the next section, is 284 suspected/confirmed and 236 surgically confirmed thyroid cancer cases. With an addition of the most recent numbers for both "unreported" cases (see this post) and "outside" cases discovered in the cancer registry (updated at the 19th session of the TUE Subcommittee), the count increases to 362 cytologically suspected/confirmed and 297 surgically confirmed cancer cases.
It should be noted that the actual number of cases is likely more due to lack of any past, present or future exhaustive investigation by Fukushima Medical University (FMU), which is necessary to gather all the cancer cases discovered outside the framework of the FHMS-TUE.
Summary on the current status of the TUE
A seven-page summary of the first through fifth rounds as well as the Age 25 Milestone Screening, "The Status of the Thyroid Ultrasound Examination Results," lists key findings from the primary and confirmatory examinations as well as the surgical information.
Below is an unofficial translation of this summary which is not officially translated.
#46 Status of the Thyroid Ultrasound Examination Results (Released on December 2, 2022) by Yuri Hiranuma on Scribd
The first round
There is no change in data with 116 suspected/confirmed thyroid cancer cases (39 males and 77 females), of which 102 underwent surgery confirming 1 benign nodule and 101 thyroid cancer cases (100 papillary thyroid cancer and 1 poorly-differentiated cancer).
The second round
There is no change in the number of suspected/confirmed thyroid cancer cases at 71 (32 males and 39 females). Surgical cases remain at 56 (55 papillary thyroid cancer and 1 "other" thyroid cancer) .
The most recent FY2020 update of the second round data was previously reported at the 42nd session (Japanese, English), with the brief update released at the last session showing the latest surgical data.
The third round
There is no change in data with 31 suspected/confirmed thyroid cancer cases (13 males and 18 males), of which 29 were surgically confirmed as papillary thyroid cancer. The final report from the 39th session in August 2020 (Japanese, English) was updated as of FY2020 and reported at the 42nd session in July 2021 (Japanese, English).
The fourth round
The fourth round, originally scheduled from April 1, 2018 through March 31, 2020, appears to be near completion. Only 3 more participated in the primary examination between April 1, 2022 and June 30, 2022, with no change in participation rate of 62.3%. 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).
The fourth round, originally scheduled from April 1, 2018 through March 31, 2020, appears to be near completion. Only 3 more participated in the primary examination between April 1, 2022 and June 30, 2022, with no change in participation rate of 62.3%. 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).
Two participants newly received the "B" assessment, but no one underwent the confirmatory examination or FNAC (fine-needle aspiration cytology). There were no new surgical cases, either.
In summary, as of June 30, 2022, the number of suspected or confirmed thyroid cancer cases for the fourth round remains at 39, of which 34 have been surgically confirmed as papillary thyroid cancer.
The previous results from the third round are as follows: 26 with "A" (6 with A1, 13 with A2 cysts, 6 with A2 nodules, and 1 with A2 cysts and nodules), 9 with "B," and 4 with no prior result.
The fifth round
The fifth round targets 252,908 individuals, excluding about 21,000 born in FY 1996 (April 2, 1996 to April 1, 1997) and about 20,000 born in FY 1997 (April 2, 1997 to April 1, 1998) who are earmarked for the Age 25 Milestone Examination in FY 2021-2022. (It has previously been discussed how this exclusion skews age distribution graphs to the left.)
The COVID-19 restrictions have had a significant impact on the progress of the fifth round which began in April 2020: school closures initially halted the school-based screening, and a burden on medical facilities reduced participation in the confirmatory examination. [Note: The fifth round was originally earmarked for FY 2020-2021 (April 2, 2020 to March 31, 2022), but the pandemic has forced an extension of the screening period by one year as described in this proposal: Elementary and middle school students from FY 2020 municipalities will undergo the TUE in FY 2020-2021, while FY 2021 municipalities will be pushed to FY 2022. For high school students, the TUE will be conducted in FY 2021-2022 with the exception of those who were already examined in FY 2020.]
The sixth round is expected to return to a two-year screening cycle beginning April 2023.
As of June 30, 2022, 80,205 participated in the primary examination, including 5,241 new participants, and its participation rate slightly increased from 29.6% to 31.7%, still quite low at only half of the fourth-round participation rate. Participation rates by age group slightly increased from 48.1% to 52.7% in ages 8-11, from 36.0% to 38.1% in ages 12-17, and from 10.3% to 10.6% in ages over 18. The primary examination results only increased by 6,046 to 75,868, and the number of "B" assessment, which qualifies for the confirmatory examination, only increased by 70 to 939.
Sixty-six newly participated in the confirmatory examination, 16 underwent FNAC, and 12 (4 males and 8 females) were newly diagnosed with suspected thyroid cancer. Their ages-at-exposure include age 2, 4, 7 and 10 years for males and ages 2, 3, 5, 6 (four), and 12 for females. Two males and all 8 females are from the FY 2020 municipalities, with the remaining two males from the FY 2021 municipalities. Their previous results include 4 with A1, 6 with A2 cyst, 1 with B, and 1 with no prior examination.
Maximum tumor diameter increased by 32.0 mm to 46.7 mm. It's not as if this increased occurred during the 3-month period since the last data compilation date, but most likely it's from a participant who never underwent prior rounds of screening.
One from FY 2020 municipalities has been confirmed with papillary thyroid cancer after undergoing surgery.
In summary, as of June 30, 2022, the number of suspected or confirmed thyroid cancer cases for the fifth round is 23, of which 7 have been surgically confirmed as papillary thyroid cancer.
The previous results from the fourth round are as follows: 18 with "A" (7 with A1, 10 with A2 cysts, 1 with A2 nodules), 3 with "B," and 1 with no prior result.
TUE questionnaire survey
Agenda for this session included a draft questionnaire survey (see this link) designed to gauge participants' understanding of the TUE itself as well as its pros and cons. The survey targets four populations including approximately 64,000 individuals under age 15, 52,000 individuals aged 15-18, 52,000 guardians of individuals aged 15-18, and 266,000 individuals over 18. Four thousands from each group will be selected as survey subjects and receive the questionnaire, with four hundred responses (written or online) expected. Selection criteria for the survey subjects are unclear other than being drawn from those who signed a consent form for the TUE. Because the consent form for participants under age 16 is signed by guardians, survey subjects for the first group (under age 15) will be the guardians by default. Survey subjects for the third group, another set of guardians, will not be necessarily from the same household as the second group.
During the discussion, questions were raised regarding the sampling method of the proposed survey, especially if the responses will constitute a fairly representation of the respective population. Discussion became further heated when the Ministry of the Environment (MOE) official Masahiro Kaminota made a request that the questionnaire (see the draft version here) should fully inform the survey subjects of "the conclusion by the UNSCEAR 2020/2021 report that future health effects by radiation exposure are not likely." His view takes words from authoritative international agencies at face values, and it appeared to draw a few endorsers. However, multiple committee members made rebuttals doubting the validity of this so-called "conclusion." Furthermore, doubts were raised regarding appropriateness to include such a definitive clause in a survey whose main purpose is to study how the pros and cons of the TUE are recognized and understood.
To put these discussions in perspective, it should not be forgotten that it was the MOE itself that planned and fully funded the IARC international expert group "TM-NUC" that ended up recommending against systematic thyroid cancer screening, like Fukushima's TUE, after future nuclear accidents. Academic discourse within Japan about thyroid cancer in Fukushima has essentially taken a binary form, with the overdiagnosis group advocating discontinuation of the TUE while FMU claims that early diagnosis and treatment have been beneficial and the TUE should be continued. Although the TM-NUC has repeatedly expressed that their work was not meant for Fukushima's TUE, their recommendations have been hailed by the overdiagnosis group as a proof that the TUE should be scaled down. However, official data and analyses sourced by international agencies are biased and lack transparency. Please see this post on how the TM-NUC transpired and this post to understand the contorted and chaotic chain of events surrounding Fukushima's thyroid cancer saga.
Journal of Epidemiology Special Issue
It was announced that the December 5, 2022 issue of Journal of Epidemiology, an official English publication of the Japan Epidemiological Association, would include 11 articles related to the FHMS. These articles can be accessed here.
Expected upcoming changes in the dataset
There are two factors inherent to the implementation structure of the TUE, leading to a smaller dataset with each screening cycle. One is a reduced size of target population and the other is a decline in participation rates, both of which are already being observed and expected to progress.
As described above, a shift of a cohort to the Milestone Screening (Age 25, Age 30, etc.) with time reduces the target population in each successive screening cycle. Furthermore, school-based screening conducted through high school slows down with each cohort graduating from high school. It will eventually come to a natural halt when the youngest cohort born in FY2011 (between April 2, 2011 and April 1, 2012) finishes high school in 2029. It should be noted that the school-based screening is completely voluntary, no less the TUE itself.
Convenience of the school-based screening contributes to a higher participation rate for ages up to 18 than past age 18. This is clearly shown in the most recent participation rates by age reported in this post: 48.1% in ages 8-11, 36.0% in ages 12-17, and 10.3% in ages over 18 in the fifth round, and 9.1% for the Age 25 Milestone Screening.
It is critical to recognize these expected changes for future datasets when reviewing the TUE data because they cast doubt on reliability and integrity of the TUE data itself and any analysis conducted. Retrieval of "missing data" due to "unreported cases" at any age is being attempted by matching the TUE data with regional (up to 2015) and national (from 2016 on) cancer registry data. For instance, reconciliation with the most recently available national cancer registry data up to 2018 (document from the 19th Subcommittee session) revealed 43 cases from the cancer registry, which are not included in the official TUE count. This is an increase from 27 cases up to 2017 (reported to the 18th Subcommittee session). Nonetheless the cancer registry is far from fool-proof because patients who move their official residence registry outside Fukushima are not reported as Fukushima cases.
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.
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 that the cancerous lesions did not newly appear but already existed yet "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 (39 cases): 6 cases with A1, 20 cases with A2 (6 nodules, 13 cysts, and 1 nodule & cyst), 9 cases with B, 4 cases previously unexamined
- Fifth round (23 cases): 7 case with A1, 11 cases with A2 (10 cysts and 1 nodule & cyst), 3 cases with B, 2 cases previously unexamined
- Age 25 Milestone Screening (16 cases): 4 cases with A2 (1 nodule and 3 cyst), 3 cases with B, 9 cases previously unexamined
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