Fukushima Thyroid Examination August 2020: 199 Surgically Confirmed as Thyroid Cancer Among 246 Cytology Suspected Cases

     The 39th session of the Oversight Committee was held on August 31, 2020, releasing some new data (as of March 31, 2020) from the second and the fourth rounds of the Thyroid Ultrasound Examination (TUE). Also released were the final results of the third round as well as the biennial report of the Age 25 Milestone Screening, both of which were first reported on June 15, 2020 at the 15th TUE Evaluation Subcommittee and covered in the previous post.  

   

Highlights

• The second round: Two new cases surgically confirmed
• The fourth round: Five new cases diagnosed as suspicious or malignant, and 2 new surgical cases. 
• Total number of suspected/confirmed thyroid cancer has increased by 5 to 246: 116 in the first round (including a single case of benign tumor), 71 in the second round, 31 in the third round, 21 in the fourth round, and 7 in Age 25 Milestone Screening.
• Total number of surgically confirmed thyroid cancer cases has increased by 4 to 199 (101 in the first round, 54 in the second round, 27 in the third round, 13 in the fourth round, and 4 in Age 25 Milestone Screening)

• Data reported is as of March 31, 2020. (Delayed reporting persists after the fourth quarterly session was skipped in 2019.)
• A list of official English translation of the 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 August 31, 2020, the 39th session of the Oversight Committee for the Fukushima Health Management Survey (FHMS) convened in Fukushima City, Fukushima Prefecture to release the fiscal year-end data as of March 31, 2020. For the third round it was the finalized report which had already been released two months earlier at the 15th session of the TUE Evaluation Subcommittee held on June 15, 2020. The Age 25 Milestone Screening results had also been released then. New information released at this time includes the second round results which were updated for the first time in 2 years and the results for the ongoing fourth round.

Summary on the current status of the TUE

     A six-page summary of the first through fourth 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.

 

#39 Status of the Thyroid Ultrasound Examination by Yuri Hiranuma 

The second round

    The second-round results, last updated as a FY 2017 supplementary report to the final report at the 31st Oversight Committee on June 18, 2018, had an addition of two surgical cases. As mentioned in the previous post, there is no official translation of the final report of the second round or its supplementary version. What was released this time has been reduced to mere 2 pages, and whether this is officially translated remains to be seen. 　

   As of March 31, 2020, the number of suspected or confirmed thyroid cancer cases in the second round remains unchanged at 71.  Of 52 cases from the FY 2014 targeted municipalities, 2 cases were newly confirmed as papillary thyroid cancer after surgery, increasing the number of surgical cases to 54 (53 papillary thyroid cancer and 1 "other" thyroid cancer).

   The previous results from the first round are as follows: 65 with "A" 33 with A1, 25 with A2 cysts, and 7 with A2 nodules), 5 with "B," and 1 with no prior screening.

The third round 

   The final report of the third-round results, released at the June 15th TUE Subcommittee, was also released at this time. This essentially means that it will (eventually) be officially translated into English unlike the final report of the second round.  

   

   As the details of the final report were discussed in the previous post, only a summary is provided below: 

   As of March 31, 2020, the number of suspected or confirmed thyroid cancer cases is 31, and 27 have been surgically confirmed as thyroid cancer, all of which being papillary thyroid cancer. 

   The previous results from the second round are as follows: 21 with "A" (7 with A1, 10 with A2 cysts, and 4 with A2 nodules), 7 with "B," and 3 with no prior screening.

The fourth round
   The fourth round, scheduled from April 1, 2018 through March 31, 2020, is still ongoing. Between December 31, 2019 and March 31, 2020, the primary examination gained 17,177 more participants, raising the current participation rate from 55.6% to 61.4%. 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, 243 newly became eligible for the confirmatory examination with 137 actually participating. The participation rate increased by 0.1% to 55.8%. Out of 15 participants that underwent FNAC, 5 (3 males and 2 females) were newly diagnosed with suspected cancer. Their third-round results include 4 A2 (3 cysts and 1 nodule) and 1 B. Their ages at the time of the 2011 nuclear accident are 9 (male), 11 (male), 12 (male), and 8 (both females). Two are from Nakadori, and other three are from Hamadori. One of the females is from a FY 2018 targeted municipality, and the rest from FY 2019 targeted municipalities.

   Two more cases were newly confirmed with papillary thyroid cancer after undergoing surgery.   

    As of March 31, 2020, the number of suspected or confirmed thyroid cancer cases for the fourth round is 21, and 13 have been surgically confirmed as thyroid cancer, all of which being papillary thyroid cancer. 

   The previous results from the third round are as follows: 17 with "A" (3 with A1, 11 with A2 cysts, and 3 with A2 nodules), 4 with "B." 

   With an addition of 2 new surgical cases (all from the FY 2018 municipalities),  a total of 13 thyroid cancer cases, all papillary thyroid cancer, have been surgically confirmed in the fourth round.

Age 25 Milestone Screening
    The Age 25 Milestone Screening results reported this time were also released at the June 15th TUE Subcommittee like the final report of the third round. Although already discussed in the previous post, the content is reposted below due to a confusing nature of this particular 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. The very first results as of March 31, 2018 (reported to the 31st session of the Oversight Committee) were included in the fourth-round results and can be accessed here (pages 31-32). Implementation schedule from the first full report as of September 30, 2018 (reported to the 33rd session of the Oversight Committee; pages 37-43 in this PDF)  is shown below. No one is supposed to undergo the regular TUE within 2 years of becoming eligible for the Age 25 Milestone Screening.

 

   In April 2017, 22,633 individuals born in FY 1992 (the FY 1992 cohort) kicked off the Age 25 Milestone Screening, which notably reduces the size of 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 an 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, and 294,213 for the fourth round.

   A fiscal year-end report for FY 2019 (link), which includes data as of March 31, 2020, adds data from 22,096 in the FY 1994 cohort. It also includes some updates on the FY 1992 and 1993 cohorts.  (Note: 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. As such, the report can include updated data from all fiscal year cohorts.)

   Since October 1, 2019, 1,301 participants newly underwent the primary examination, including 16 born in FY 1992, 63 in FY 1993, and 1,222 in FY 1994. An overall participation rate actually decreased from 9.6% to 8.4% due to a larger denominator from an addition of the FY 1994 cohort. A participation rate for the FY 1994 is 5.5%. It remained at 9.9% for the FY 1992 cohort and increased by 0.3% to 9.6% for the FY 1993 cohort. Because the participation is not limited to a specific screening year as explained earlier, it is likely that the FY 1994 cohort will eventually have a higher participation rate. A fiscal year-end participation rate for the FY 1993 cohort as of March 31, 20019 was 4.5%, which has now more than doubled a year later. Still, these participation rates are conspicuously much lower than the main TUE.

   Eligibility for the confirmatory examination (a.k.a. "B" assessment in the primary examination) was gained for 46 more participants. Of 244 needing the confirmatory examination, 23 newly participated, and 3 newly underwent FNAC. All three, all females, were diagnosed with suspected thyroid cancer, and one had "B" in the previous screening whereas 2 never participated in the TUE.

  Thus the number of suspected or confirmed thyroid cancer cases from the Age 25 Milestone Screening increased by 3 to 7. The results from the prior screening are as follows: 1 with A2 (unclear if cyst or nodule due to lack of reporting), 1 with "B," and 5 with no prior screening.

   With an addition of 3 new surgical cases, a total of 4 thyroid cancer cases (3 papillary thyroid cancers and 1 follicular thyroid cancer) were surgically confirmed in the Age 25 Milestone Screening.

   The average tumor diameter from the FNAC was 22.6 ± 15.6 mm (range 10.8 - 49.9 mm). Note that this is a drastic jump from what was reported last time, 14.5 ± 2.7mm (range 12.3 - 18.0 mm), with the average diameter increasing by a factor of 1.5 and the maximum diameter nearly tripling. This is likely due to a single case of 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 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 (21 cases): 3 cases with A1, 14 cases with A2 (3 nodules and 11 cysts), 4 cases with B
• 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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Addendum (Note: this is for record-keeping, not an endorsement of any sort.)

   The previous post covered a group promoting an overdiagnosis theory, "Japan Consortium for Juvenile Thyroid Cancer (JTJTC)," which was spearheaded by Toru Takano of Osaka University, a former controversial member of the Oversight Committee and the TUE Subcommittee.  The member roster includes those who were aggressively attributing Fukushima's thyroid cancer to overdiagnosis: Akira Otsuru, Tomotaka Sobue, Toru Takano, Shoichiro Tsugane, and Sanae Midorikawa.

   As explained in the previous post, objectives of the group might not be totally obvious from the website. Rather, their beliefs and claims are explained by Midorikawa on the website of Miyagi Gakuin Women's University (link). Excerpts are translated below:

• It is not that radiation exposure led to an increase in thyroid cancer in Fukushima.
• Many thyroid cancers happen to be "discovered" because of the Thyroid Ultrasound Examination (TUE).
• Further, majority of those thyroid cancer cases would not have been diagnosed if it weren't for the TUE: They are harmless cancers which probably would have remained undetected for life. (This is called overdiagnosis.)
• Even Fukushima residents and their families are unaware of this fact, and they continue to participate in the TUE.

   The JTJTC even boasts several international advisory members, as described on their website. There is also a Japanese Twitter account called "Save Children from Overdiagnosis (SCO)" affiliated with JTJTC, clearly intended to inform the public of their agenda, often tweeting video clips by Takano, Midorikawa, and Ohtsuru.

   Midorikawa, a former director of the school screening, and Ohtsuru, a former director of the TUE, have publicly turned against their former colleagues at Fukushima Medical University (FMU) in their letter to the editor regarding a recent FMU paper on the non-malignant cytological examination results from the first and second rounds.  Criticizing that FMU's use of the term "overtreatment" is misleading, Midorikawa and Ohtsuru ultimately recommends halting the school screening based on various pieces of "evidence" which are meant to rationalize their claim of overdiagnosis. Their discourse, built on an unproven assumption of overdiagnosis, is illogical at times.

   Takano has done his share of pushing the group's biased view of overdiagnosis, actively publishing papers in various academic journals. In a letter to the editor published in the June 2019 issue of the Archives of Pathology and Laboratory Medicine, Takano even claimed that overdiagnosis has put Fukushima's children in danger, prompting a reply from FMU officials describing "an accurate picture" of the TUE.

   Albeit a common thread of denying radiation effects due to "lower doses in Fukushima than in Chernobyl," JTJTC's activities deviate from FMU's work by emphasizing harm (mostly psychosocial) originating in the TUE, posing constant hindrance to FMU's plan to continue the TUE. Their garbled views might make FMU's claims appear reasonable, but they are actually a good match when it comes to garbling.