Overview
On July 27, 2021, the 42nd 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 March 31, 2021) from the Thyroid Ultrasound Examination (TUE). The main results reported this time are for the fourth and fifth rounds as well as the Age 25 Milestone Screening. In addition, March 31st marks the end of fiscal year in Japan prompting a release of fiscal year-end reports, which included an updated version of the second-round results and a FY 2020 supplementary version for the third round.
The 42nd session, held only two months after the last session, was the final session for this group of committee members whose two-year term concluded on July 31, 2021. It was also held a month after the 17th session of the Thyroid Examination Evaluation Subcommittee (herein the TUE Subcommittee), which was also the final session of the two-year term for the subcommittee members. Although the TUE Subcommittee was discussing analytical results of the third-round data, no "interim summary" has been drawn up.
The Oversight Committee sessions were only held three times during FY 2018 and 2020, rather than quarterly as specified in the implementation guidelines. The data gap created during FY 2020 with 3-month worth of data reported every 4 months was "closed" this time with a report of 6-month worth of data. With the 43rd session scheduled to be held on October 15, 2021, the Oversight Committee appears to be back on regular schedule at least for the current fiscal year 2021.
The pandemic restrictions are still hampering the progress of the fifth round: Once again, the confirmatory examination results were not reported.
At this time, an official English translation is available up to the 40th session of the Oversight Committee on the website for the Radiation Medical Science Center of the Fukushima Health Management Survey (RMSC/FHMS). This means that the final results of the third round, released at the 39th session in August 2020, is finally available in English on pages 2-20 of this report. (Update on September 18, 2022: English translation of the 42nd session is available here.)
Highlights
- The second round: 1 new surgical case.
- The third round: 2 new surgical cases.
- The fourth round: 3 new cases diagnosed as suspicious or malignant, and 2 new surgical cases.
- The fifth round: no report on the confirmatory examination.
- The Age 25 Milestone Screening: 1 new case diagnosed as suspicious or malignant, and no new surgical cases.
- Total number of suspected/confirmed thyroid cancer has increased by 4 to 260: 116 in the first round (including a single case of benign tumor), 71 in the second round, 31 in the third round, 33 in the fourth round, and 9 in Age 25 Milestone Screening.
- Total number of surgically confirmed thyroid cancer cases has increased by 5 to 218 (101 in the first round, 55 in the second round, 29 in the third round, 27 in the fourth round, and 6 in Age 25 Milestone Screening,
The latest overall results including the "unreported" and cancer registry cases
Official count, as reported in the summary document shown in the next section, is 260 suspected/confirmed and 218 surgically confirmed thyroid cancer cases. An addition of more recent "unreported" cases as well as "outside" cases discovered in cancer registry makes the count a little more complete with 319 cytologically suspected/confirmed and 261 surgically confirmed cancer cases. It should be noted that the actual number of cases is likely more than these as no exhaustive investigation has been and will be conducted by FMU to fully report all the cancer cases discovered outside the framework of the FHMS-TUE.
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 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.
The second round
An updated version of the second-round results was released at the end of FY 2020 reflecting slight changes in the number of participants and test results since the FY 2017 supplementary version. Corrections were also made for female proportions of the primary examination participants which were erroneously reported as female proportions of the target population. Similar corrections were made for the first-round results, but its updated version was posted as a replacement for the FY 2017 condensed version which is the most recent condensed version of the first-round results.
The number of suspected thyroid cancer remains the same at 71, but with an addition of one new surgical case which turned out to be a papillary thyroid cancer, the number of confirmed cancer cases now stands at 55 including 54 papillary thyroid cancers and 1 other cancer.
The third round
For the third-round results, a FY 2020 supplementary version of the final results was released to reflect changes in the numbers of participants and test results since the final results were reported in the summer of 2020. The number of suspected thyroid cancer cases remains the same at 31, but an addition of 2 surgical cases increases the number of confirmed thyroid cancer cases to 29, all papillary thyroid cancers.
An official English translation of the final results of the third round is available here.
The fourth round
Although the fourth round, originally scheduled from April 1, 2018 through March 31, 2020, is still ongoing, only 442 participated in the primary examination between September 30, 2020 and March 31, 2021, slightly raising the current participation rate by 0.2% to 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), although it is slowly approaching the third round.
Having received the "B" assessment in the primary examination, 9 newly became eligible for the confirmatory examination. With an additional 86 participants, the confirmatory examination increased its participation rate by 5.8% to 73.3%. Out of 8 participants newly undergoing FNAC, 3 individuals (2 males and 1 female) were diagnosed with suspected thyroid cancer. Their third-round results were A1, B, and no previous examination. Two males were ages 8 and 9 and the female was age 8 at the time of the 2011 nuclear accident. One of the males is from the FY 2018 municipalities, and the other male and the female are from the FY 2019 municipalities. One is from Nakadori and two are from Hamadori.
Two more cases (one from the FY 2018 municipalities and one from the FY 2019 municipalities) were newly confirmed with papillary thyroid cancer after undergoing surgery.
In summary, as of March 31, 2021, the number of suspected or confirmed thyroid cancer cases for the fourth round is 33, of which 27 have been surgically confirmed as papillary thyroid cancer.
The previous results from the third round are as follows: 24 with "A" (6 with A1, 12 with A2 cysts, 5 with A2 nodules, and 1 with A2 cysts and nodules), 6 with "B," and 3 with no prior result.
The fifth round
The fifth round targets 252,842 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. (The previous post 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.
As of March 31, 2021, 23,412 participated in the primary examination, including 20,342 new participants, and its participation rate increased from 1.2% to 9.3%, still quite low. Participation rates by age group are 16.4% in ages 8-11, 9.7% in ages 12-17, and 4.2% in ages over 18, showing a slow progress of school-bases examination. The primary examination results are available for 21,624 (92.4%), and 228 were assessed as "B" qualifying for the confirmatory examination. Once again, no confirmatory examination results were reported due to a very small number of participants.
The fifth round was originally earmarked for FY 2020-2021 (April 2, 2020 to March 31, 2022), but the pandemic impact 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.
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. Implementation schedule as of September 30, 2018, reported to the 33rd session of the Oversight Committee, can be found here. (No one is supposed to undergo a regular TUE within 2 years of becoming eligible for the Age 25 Milestone Screening.)
Transition of each FY birth cohort to the Age 25 Milestone Screening reduces a 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 the 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 381,237 for the second round (increased because those who were in utero at the time of the accident were included), 336,667 for the third round, 294,239 for the fourth round, and now 252,842 for the fifth round.
The results reported this time are from the data up to March 31, 2021, newly including 21,056 who were born in FY1995 in the target population. Since the previously reported results as of September 30, 2020, 1,667 more participated in the primary examination, with total participants being 7,612, A participation rate actually saw a slightly decrease by 0.2% to 8.7%, due to the increased target population of 87,694. 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. Thus participation rates by FY birth cohorts might continue to change as the screening progresses.
Seventy-eight more became eligible for the confirmatory examination (a.k.a. "B" assessment in the primary examination). Of 359 qualifying for the confirmatory examination, 239 have undergone it, with 18 newly participating. Only one person newly underwent FNAC, and this person, a female, was diagnosed with suspected thyroid cancer. There was a confusion about her prior result, which was verbally reported as no prior examination while the written report shows it was A2. Curiously, the verbal report specified one prior A2 case as nodule, whereas an existing prior A2 case never had clarification as to whether it was cyst or nodule.
Thus the number of suspected or confirmed thyroid cancer cases from the Age 25 Milestone Screening increased by 1 to 9. The results from the prior screening have two possibilities depending on which information is accurate, verbal or written. (Note on October 15, 2021: the verbal information was accurate, and a corrected version of the report was released.) a) verbal: 1 with A2 nodule, 2 with "B," and 6 with no prior screening.
b) written: 2 with A2 (at least one with nodule according to the verbal report), 2 with "B," and 5 with no prior screening.
No new surgical cases were added, and surgically confirmed thyroid cancer cases remain as 6, including 5 papillary thyroid cancers and 1 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 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 (33 cases): 6 cases with A1, 18 cases with A2 (5 nodules, 12 cysts, and 1 nodule & cyst), 6 cases with B, 3 cases previously unexamined
- Age 25 Milestone Screening (9 cases): Due to inconsistencies between verbal and written reports, both scenarios are listed below. (Note on October 15, 2021: the verbal information was accurate, and a corrected version of the report was released.)
Verbal report: 1 case with A2 (nodule), 2 cases with B, 6 cases previously unexamined
Written report: 2 cases with A2 (1 nodule and 1 unknown?), 2 cases with B, 5 cases previously unexamined
