After a 4½-month hiatus, the 40th session of the Oversight Committee was held on January 15, 2021, releasing new data (as of June 30, 2020) from the fourth and fifth rounds of the Thyroid Ultrasound Examination (TUE). The pandemic restrictions have essentially stalled the school-based screening for the fifth round, and the only cancer data updated was that of the fourth round.
Highlights
- The fourth round: 6 new cases diagnosed as suspicious or malignant, and 3 new surgical cases.
- Total number of suspected/confirmed thyroid cancer has increased by 6 to 252: 116 in the first round (including a single case of benign tumor), 71 in the second round, 31 in the third round, 27 in the fourth round, and 7 in Age 25 Milestone Screening.
- Total number of surgically confirmed thyroid cancer cases has increased by 4 to 202 (101 in the first round, 54 in the second round, 27 in the third round, 16 in the fourth round, and 4 in Age 25 Milestone Screening)
- Data reported is as of June 30, 2020. (Delayed reporting persists after the fourth quarterly session was skipped in 2019 and now also in 2020.)
- A list of official English translation of the TUE results is available on the website for the Radiation Medical Science Center of the Fukushima Health Management Survey. No translation is available for the 2020 sessions at this time.
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 January 15, 2021, the 40th session of the Oversight Committee for the Fukushima Health Management Survey (FHMS) convened in Fukushima City, Fukushima Prefecture to release data as of June 30, 2020. As the third round results were finalized 7 months ago and the fifth round just began in April 2020, new information released on thyroid cancer was essentially from the fourth round only.
Summary on the current status of the TUE
A six-page summary of the first through fifth 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.
Below is an unofficial translation of this summary which is not officially translated.
The fourth round
The fourth round, scheduled from April 1, 2018 through March 31, 2020, is still ongoing. Between April 1, 2020 and June 30, 2020, the primary examination gained only 435 more participants, raising the current participation rate by 0.1% to 61.5%. A reminder: 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), although it is approaching the third round.
The fourth round, scheduled from April 1, 2018 through March 31, 2020, is still ongoing. Between April 1, 2020 and June 30, 2020, the primary examination gained only 435 more participants, raising the current participation rate by 0.1% to 61.5%. A reminder: 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), although it is approaching the third round.
Having received the "B" assessment in the primary examination, 35 newly became eligible for the confirmatory examination. With an additional 78 actually participating, the participation rate increased by 4.3% to 60.1%. Out of 15 participants undergoing FNAC, 6 females were diagnosed with suspected cancer. Their third-round results include 2 with A1, 2 with A2 (1 cyst and 1 nodule), 1 with B, and 1 with no previous examination. Their ages at the time of the 2011 nuclear accident are 0, 2, 6, 6, 10 and 11. It is notable that this marks the first time that thyroid cancer was detected in individuals aged 0 and 2 at the time of radiation exposure. Two are from Nakadori, one is from Hamadori, and remaining three are from Aizu. One is from a FY 2018 municipality, and the rest from FY 2019 municipalities.
Three more cases (all from FY 2019 municipalities) were newly confirmed with papillary thyroid cancer after undergoing surgery.
In summary, as of June 30, 2020, the number of suspected or confirmed thyroid cancer cases for the fourth round is 27, and 16 have been surgically confirmed as thyroid cancer, all papillary thyroid cancer.
The previous results from the third round are as follows: 21 with "A" (5 with A1, 12 with A2 cysts, and 4 with A2 nodules), 5 with "B," and 1 with no prior result.
The fifth round
The fifth round targets 252,821 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. (See the next section to learn what this exclusion means for the age distribution graphs.)
Although the fifth round began in April 2020, its progress has been hampered by school closures and other restrictions due to the COVID-19 pandemic. As of June 30, 2020, only 564 participated in the primary examination with 487 (86.3%) in the age 18-24 category. Due to cancellation of the school-based screening in accordance with school closures, only 77 participated in the younger age group (8-17). The primary examination results are available for only 41 out of 564, and one person was assessed as "B."
No confirmatory examination has been conducted as of June 30, 2020, and there are no suspected/confirmed cancer cases for the fifth round at this time.
Because of the pandemic delay, a proposal was submitted by FMU to extend a two-year screening cycle to three years just for the fifth round. 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 already examined in FY 2020.
Age distribution graphs
As the the target population size continues to dwindle in accordance with an exclusion of a respective FY cohort awaiting the Age 25 Milestone Examination within 2 years, the age distribution is skewed to the left, lending an "unnatural" appearance as thyroid cancer is known to increase in adulthood. This is depicted below in a succession of age distribution graphs from the first to fourth rounds taken from the FY2019 report of the Fukushima Health Management Survey accessed on this page.
Graphs on the left show age-at-exposure distribution. The shaded area starts to be seen in the right area of the graph from the third round on. Ordinarily, for thyroid cancer, an upward trend is expected with age, beginning in early 20's. In the age-at-exposure distribution, that corresponds to the shaded area depicting missing data from those transitioning from the regular TUE to the Age 25 Milestone Examination. The age-at-examination distribution graphs on the right show 23 as the maximum age, totally disregarding the missing data.
One more thing to note: The age-at-examination distribution graphs here might not necessarily show an upward trend with age. This might partially be due to plummeted participation by those ≥ age 18. Participation rates by age groups for the fourth round are 85.4% for ages 6-11, 82.0% for ages 12-17, and 12.4% for ages 18-24.
As young adults transition to the Age 25 Milestone Screening, participation dips even further; the current participation rate is 8.4%. Thus data gathering becomes more difficult as they leave the regular TUE. Some might undergo cancer screening on their own, totally outside the FHMS system. FMU officials plan to rely on the national cancer registry data mandated in 2016 to fill the void. However, with young adults relocating outside Fukushima Prefecture as life goes on, how exhaustive and reliable the cancer registry data might be for this purpose remains to be seen.
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| The first round as of March 31, 2018 |
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| The second round as of March 31, 2018 |
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| The third round as of June 30, 2019 |
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| The fourth round as of June 30, 2019 |
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| The fourth round (age-at-exposure) as of June 30, 2020 |
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 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 (27 cases): 5 cases with A1, 16 cases with A2 (4 nodules and 12 cysts), 5 cases with B, 1 case previously unexamined
- 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
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