Overview
On May 17, 2021, the 41st 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 September 30, 2020) from the Thyroid Ultrasound Examination (TUE). The results reported this time are for the fourth and fifth rounds as well as the Age 25 Milestone Screening.
The 41st session was held four months after the last session, and it appears that it has become "regular" to hold the Oversight Committee sessions three times a year rather than quarterly as specified in the implementation guidelines. With the data released at each session only including 3 months worth of results while sessions held every 4 months since 2019, a data gap keeps increasing. A spring session such as this used to report data up to March 31, which is the end of a fiscal year in Japan, but now we are 6 months behind on data release.
The pandemic restrictions are still slowing the fifth round, and no results were reported for the confirmatory examination of the fifth round, which has only been sparsely conducted.
Highlights
- The fourth round: 3 new cases diagnosed as suspicious or malignant, and 9 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 2 new surgical cases.
- Total number of suspected/confirmed thyroid cancer has increased by 4 to 256: 116 in the first round (including a single case of benign tumor), 71 in the second round, 31 in the third round, 30 in the fourth round, and 8 in Age 25 Milestone Screening.
- Total number of surgically confirmed thyroid cancer cases has increased by 11 to 213 (101 in the first round, 54 in the second round, 27 in the third round, 25 in the fourth round, and 6 in Age 25 Milestone Screening)
- Data reported is as of September 30, 2020. (Delayed reporting persists after the fourth quarterly session was skipped in 2019, 2020, and now likely 2021.)
- A list of official English translation of the FHMS reports including the TUE results is available on the website for the Radiation Medical Science Center of the Fukushima Health Management Survey (RMSC/FHMS). At this time, translation is available for the first two 2020 sessions, the 37th and 38th sessions. The final results of the third round, released at the 39th session in August 2020, is not yet available in English.
The latest overall results including the "unreported" and cancer registry cases
The table below shows a new set of numbers for "unreported" cases: 35 malignant or suspicious, 35 surgical, and 19 cancer cases (previously 12, 12, and 11, respectively, as explained here and reported in this paper). These 35 cases are part of 180 surgical cases operated at the Fukushima Medical University (FMU) hospital as of December 31, 2018: unlike other 145, they had not been included in a report to the Oversight Committee,
Shinichi Suzuki, an FMU thyroid surgeon, has presented this data at various domestic and international academic meetings since 2019 including a February 3, 2020 keynote lecture at the Second International Symposium by RMSC/FHMS. More than a year later, it finally became part of the official TUE data when it was reported to the 16th TUE Subcommittee held on March 22, 2021. (Note: This report is merely an excerpt from a symposium abstract. The English abstract can be accessed here.) There is no way to confirm, but it is assumed that previous 12 unreported malignant/suspicious cases, of which 11 are confirmed as cancer, are likely included in these 35 cases.
There is also a new row added to the table, showing 24 thyroid cancer cases which were diagnosed outside the framework of the TUE but found in Fukushima Prefecture's cancer registry from 2012 to 2017. This was also reported at the 16th TUE Subcommittee.
Official count, as reported in the summary document shown in the next section, is 256 suspected/confirmed and 213 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 315 cytologically suspected/confirmed and 256 surgically confirmed cancer. It should be noted that the actual number of cases is likely more than these.
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 fourth round
The fourth round, originally scheduled from April 1, 2018 through March 31, 2020, is still ongoing. Between June 30, 2020 and September 30, 2020, the primary examination gained 1,851 more participants, raising the current participation rate by 0.6% to 62.1%. An important 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 slowly approaching the third round.
The fourth round, originally scheduled from April 1, 2018 through March 31, 2020, is still ongoing. Between June 30, 2020 and September 30, 2020, the primary examination gained 1,851 more participants, raising the current participation rate by 0.6% to 62.1%. An important 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 slowly approaching the third round.
Having received the "B" assessment in the primary examination, 12 newly became eligible for the confirmatory examination. With an additional 109 participants, the confirmatory examination increased its participation rate by 7.4% to 67.5%. Out of 10 participants newly undergoing FNAC, 3 individuals (1 male and 2 females) were diagnosed with suspected cancer. Their third-round results were 2 with A2 (1 nodule and 1 nodule & cyst) and 1 with no previous examination. The male was age 9 and the females were age 5 and 9 at the time of the 2011 nuclear accident. All three are from the FY 2019 municipalities, and two are from Hamadori and one is from Aizu.
Nine more cases (two from the FY 2018 municipalities and seven from the FY 2019 municipalities) were newly confirmed with papillary thyroid cancer after undergoing surgery.
In summary, as of September 30, 2020, the number of suspected or confirmed thyroid cancer cases for the fourth round is 30, of which 25 have been surgically confirmed as thyroid cancer: all papillary thyroid cancer.
The previous results from the third round are as follows: 23 with "A" (5 with A1, 12 with A2 cysts, 5 with A2 nodules, and 1 with A2 cysts and nodules), 5 with "B," and 2 with no prior result.
The fifth round
The fifth round targets 252,828 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 significantly impacted 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 September 30, 2020, 3,070 participated in the primary examination, including 2,506 new participants, but its participation rate remains extremely low at 1.2%. Of 2,506 new participants about half is in the age 8-17 category (571 in age 8-11 and 678 in age 12-17), and the other half in the age 18-24 category. The primary examination results are available for 2,138 (69.8%), and a total of 26 were assessed as "B."
Because very few had undergone the confirmatory examination as of September 30, 2020, the results were not reported at this time.
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 the regular TUE within 2 years of becoming eligible for the 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 the 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, 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, 294,242 for the fourth round, and now 252,828 for the fifth round.
The results reported this time are from the data up to September 30, 2020. Since the previously reported results as of March 31, 2020, 376 more participated in the primary examination, but the total participants are 5,954 out of the target population of 66,637, and an overall participation rate only slightly increased by 0.5% to 8.9%, conspicuously much lower than the main TUE. 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.
Thirty-seven more became eligible for the confirmatory examination (a.k.a. "B" assessment in the primary examination). Of 281 needing the confirmatory examination, 221 has undergone it, with 53 newly participating. Three newly underwent FNAC, and one female with a prior result of "B" was diagnosed with suspected thyroid cancer.
Thus the number of suspected or confirmed thyroid cancer cases from the Age 25 Milestone Screening increased by 1 to 8. The results from the prior screening are as follows: 1 with A2 (unclear if cyst or nodule due to lack of reporting), 2 with "B," and 5 with no prior screening.
With an addition of 2 new surgical cases, a total of 6 thyroid cancer cases (5 papillary thyroid cancers and 1 follicular thyroid cancer) were surgically confirmed in the Age 25 Milestone Screening.
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 (30 cases): 5 cases with A1, 18 cases with A2 (5 nodules, 12 cysts, and 1 nodule & cyst), 5 cases with B, 2 cases previously unexamined
- Age 25 Milestone Screening (8 cases): 1 case with A2 (it was never reported if nodule or cyst), 2 cases with B, 5 cases previously unexamined
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