Note: From this post onward, the terms "Age 25+ Survey" and "Age 30+ Survey" are to replace "Age 25 Milestone Screening" and "Age 30 Milestone Screening," in accordance with the terms used in official translation of the reports.
Overview
On May 10, 2024, the 51st 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 December 31, 2023) from the fifth and sixth rounds of the Thyroid Ultrasound Examination (TUE). It amounts to a 3-month worth of data since the previous session held on February 2, 2024 (English translation here).
Official translations of the reports from the Oversight Committee are available on the Materials and Minutes of Prefectural Oversight Committee Meetings page (link) on the website of Radiation Medical Science Center of the Fukushima Health Management Survey (RMSC/FHMS). For the current session discussed in this post, the official translation is already available. Indeed it has been over 2 months since the 51st session and personal circumstances delayed this post, but it seems that publishing of English translations is now more timely after marked delays of the last few years. This website also shows an overview of the FHMS and the TUE itself, which might be informative to those unfamiliar with them.
Highlights
- The fifth round: 2 new cases diagnosed as suspicious or malignant, and 2 new surgical case.
- The sixth round: no confirmatory examination results available.
- Total number of suspicious or malignant cases has increased by 2 to 330: 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, 45 in the fifth round, and 23 in the Age 25+ Survey and 5 in the Age 30+ Survey.
- Total number of surgically confirmed thyroid cancer cases has increased by 2 to 276 (101 in the first round, 56 in the second round, 29 in the third round, 34 in the fourth round, 36 in the fifth round, 17 in the Age 25+ Survey and 3 in the Age 30+ Survey.
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 330 suspicious or malignant cases and 276 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 408 cytologically suspicious or malignant and 338 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 nine-page summary of the first through sixth rounds as well as the Age 25+ and Age 30+ Surveys, "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.
Below is a brief descriptive summary of each round, regardless of the update status, provided for easy reference.
The first round
There is no change in data with 116 suspicious or malignant cases (39 males and 77 females), of which 102 underwent surgery which confirmed 1 case with 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 suspicious or malignant cases at 71 (32 males and 39 females). Surgically confirmed 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 suspicious or malignant 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
There is no change in data with 39 suspicious or malignant cases (17 males and 22 females), of which 34 have been surgically confirmed as papillary thyroid cancer. The final report was presented to the 20th TUE Subcommittee session on March 20, 2023 but not independently to the Oversight Committee. Since the meeting materials from the TUE Subcommittee are not officially translated, the final report will also not be translated. However, it is identical to the version presented to the 46th session in December 2022 whose translation can be found here.
There is no change in data with 39 suspicious or malignant cases (17 males and 22 females), of which 34 have been surgically confirmed as papillary thyroid cancer. The final report was presented to the 20th TUE Subcommittee session on March 20, 2023 but not independently to the Oversight Committee. Since the meeting materials from the TUE Subcommittee are not officially translated, the final report will also not be translated. However, it is identical to the version presented to the 46th session in December 2022 whose translation can be found here.
The fifth round (updated this time)
The fifth round targets 252,938 individuals who were born in FY 1998-2011. Originally earmarked for FY 2020-21 (April 2, 2020 to March 31, 2022), its implementation was extended by 1 year due to the COVID-19 pandemic. With only a very small increase of new participants in the primary examination and no new participants eligible for the confirmatory examination, the fifth round finally appears to be near completion although it might be a while before the final version of the results is released. (For reference, the final results of the fourth round weren't released until 3 years past its scheduled completion date of March 2020.)
As of December 31, 2023, the total number of participants in the primary examination was 113,950 with an addition of 9 new participants (5 residing outside Fukushima). There was a slight increase of 0.1% in its overall participation rate at 45.1% which is attributed by the ages over 18 group: 74.0% in ages 8-11, 57.8% in ages 12-17, and 11.3% in ages over 18. The primary examination results increased by 5 to 113,946 with the completion rate of 100%, and there was no new "B" assessment, and the number of individuals qualifying for the confirmatory examination remains at 1,346.
The number of new participants in the confirmatory examination was 32, and 3 underwent FNAC with 2 being newly diagnosed with suspicion of thyroid cancer. The two were both females (ages-at-exposure of 0 year and 7 years). One female was from the FY 2020 municipalities and the other from the FY2021 municipalities, and one was from Hama-dori whereas the other from Naka-dori. Their previous results included A1 and A2 nodules/cysts.
There were 2 new surgical cases with 1 each from the FY2020 and the FY2021 municipalities. Both cases were confirmed as papillary thyroid cancer.
In summary, as of December 31, 2023, the number of suspicious or malignant cases for the fifth round is 45, of which 36 have been surgically confirmed as papillary thyroid cancer. The previous results from the fourth round are as follows: 33 with "A" (11 with A1, 20 with A2 cysts, 2 with A2 nodules/cysts), 6 with "B," and 6 with no prior result.
The fifth round now has more suspicious or confirmed cases than the fourth round (45 vs. 39), and the FMU officials explained at the 50th session that this was due to a natural shift of the target population into ages at which thyroid cancer frequency begins to increase. Also there are now more females diagnosed with suspicion of thyroid cancer, and thyroid cancer incidence is usually higher in females. Aside from any consideration for possible radiation effects, natural sex- and age-related changes in incidence make a clear understanding of the situation more complicated, which is further complicated by any more "unreported" cases which have not come to the surface.
The Sixth Round (updated this time)
The sixth round began in April 2023 with a target population of 211,885 which is 41,053 fewer than the fifth round, reflecting an additional exclusion of those born in FY 1998-1999 who will transition to the Age 25+ Survey.
As of December 31, 2023, the number of primary examination participants increased by 16,131 to a total of 34,425, which nearly doubled the participation rate from 8.6% to 16.3%. Of 27,923 whose results are available, 382 received the B assessment. There has been very little progress of the confirmatory examination, and its results were not reported.
[Important note: Transition of each FY birth cohort to the Milestone Screening (Age 25+ Survey and so on) reduces a target population for the main TUE. This reduction began in the third round conducted during FY 2016-2017, which excluded the FY 1992-1993 cohorts in anticipation of the upcoming the Age 25+ Survey. With each FY birth cohort including about 22,000 individuals, this is a sizable reduction which continues as the TUE target population ages. (An exception is an increase from 367,637 for the first round to 381,237 for the second round which is due to an inclusion of those who were in utero at the time of the accident.) From then on, it has decreased to 336,667 for the third round, 294,228 for the fourth round, 252,938 for the fifth round, and now 211,865 for the sixth round. The January 2021 post explains how this ongoing transition skews age distribution graphs to the left.]
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, and 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, and 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, and 4 cases previously unexamined
- Fifth round (45 cases): 11 cases with A1, 21 cases with A2 (20 cysts and 2 nodules & cysts), 6 cases with B, and 6 cases previously unexamined
- Age 25+ Survey (23 cases): 1 case with A1, 4 cases with A2 (1 nodule and 3 cyst), 4 cases with B, and 14 cases previously unexamined
- Age 30+ Survey (5 cases): 1 case with A2 (1 cyst), 1 case with B, and 3 cases previously unexamined