Fukushima Thyroid Examination May 2022: 226 Surgically Confirmed as Thyroid Cancer Among 274 Cytology Suspected Cases

 

Overview

    On May 13, 2022, the 44th 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, 2021) from the fourth and fifth rounds as well as the Age 25 Milestone Screening of the Thyroid Ultrasound Examination (TUE).  The fifth-round data reported this time includes more details of the confirmatory examination results, and the first age & sex distribution graph was released for the Age 25 Milestone Screening. 

    The 44th session was the second session of the fifth term (August 2021-July 2023) of the Oversight Committee. (The first of two-year terms consisting of quarterly sessions commenced at the 11th session on June 5, 2013, after the departure of Shunich Yamashita amid controversy surrounding "secret meetings.")  It was unprecedented not only in the length of time that elapsed (seven months) since the previous session, but also in an unusual turnover of committee members at merely the second session: four members resigned, including Hokuto Hoshi who served as Chair for the five consecutive terms as well as Toshiya Inaba who as a fifth-term member and Vice Chair would have been a strong candidate to as new Chair. Everyone but Inaba has been replaced by someone from respective organizations, and the member roster stands at 17 for now.

   Hoshi's resignation was due to his political activity as a candidate in the summer 2022 election from the Fukushima electoral district for the House of Councillors (upper house) of the National Diet of Japan. His declaration for candidacy in mid-December 2021 meant the end of his reign as the Oversight Committee Chair, and it turns out he did resign as a committee member a month later. His resignation was a welcome news to some of the long-time audience faithfully following the Oversight Committee. (Hoshi would often diverge into lengthy monologues and even occasional emotional outbursts during these sessions, in addition to expressing displeasure and irritation by questions and comments at press conferences. None of these behaviors seemed appropriate as Chair.) 

     Hoshi has now been replaced by Noboru Takamura of Nagasaki University who is also serving his fifth term. Takamura is a known disciple of late Shigenobu Nagataki and infamous Shunichi Yamashita. It should not be forgotten that shortly after the 2011 Fukushima nuclear accident Fukushima Prefecture appointed Yamashita and Takamura to be radiation health risk management advisors. The pair went around Fukushima, downplaying potential health effects of radiation exposure in order to soothe people's fear. An excerpt below is from a Wall Street Journal article published on August 16, 2011.  (The article can be read here.)

On March 25, 2011 Takamura told about 600 villagers that they could continue to live safely in Iitate if they took precautions like wearing face masks outdoors and washing hands frequently, according to the village newsletter. Mr. Takamura said recently that radiation readings in the village were below 100 millisieverts — considered the threshold for health risk.

   Takamura is also known to have told Iitate Village residents that children could safely play outside up to 10 µSv/h of the ambient radiation. Besides his involvement with fieldwork in Kawauchi Village and Tomioka Town through respective Reconstruction Promotion Bases at Nagasaki University, Takamura is also curator of the Great Japan Earthquake and Nuclear Disaster Memorial Museum in Futaba Town, as described in this interview. 

     After Yamashita's well-publicized departure from Chair in March 2013 which coincided with the end of FY 2012, it seems that the Oversight Committee has come full circle with Takamura as Chair.

    On a separate note, only 3 months worth of new data as of September 30, 2021 was reported despite the lengthy pause of 7 months since the last session. The Oversight Committee is supposed to meet quarterly according to the implementation guidelines, but only 3 sessions each were held in 2019 and 2020, gradually widening the gap between compilation dates and report dates of the data. Quarterly sessions returned in 2021, and the data reporting was finally catching up, but now it's behind about 6 months even though other non-thyroid surveys were reporting the end-of-FY data as of March 31, 2021.

   At this time, an official English translation is still only available up to the 40th session of the Oversight Committee. The Radiation Medical Science Center of the Fukushima Health Management Survey (RMSC/FHMS) has rearranged its website, and the meeting materials are now available on this page. The final results of the third round, released at the 39th session in August 2020, is also available in English on pages 2-20 of this report.

   

Highlights

• The fourth round: 1 new case diagnosed as suspicious or malignant, and 3 new surgical cases. 
• The fifth round: 3 new cases diagnosed as suspicious or malignant, and 2 new surgical cases.
• Age 25 Milestone Screening: 4 new cases diagnosed as suspicious or malignant, and no new surgical cases.
• Total number of suspected/confirmed thyroid cancer has increased by 8 to 274: 116 in the first round (including a single case of benign tumor), 71 in the second round, 31 in the third round, 37 in the fourth round, 6 in the fifth round, and 13 in Age 25 Milestone Screening.
• Total number of surgically confirmed thyroid cancer cases has increased by 5 to 226 (101 in the first round, 55 in the second round, 29 in the third round, 32 in the fourth round, 3 in the fifth round, and 6 in Age 25 Milestone Screening,

The latest overall results including the "unreported" and cancer registry cases

    Please refer to the post on the May 2021 report regarding the details of "unreported" cases and cancer registry data.

    Official count, as reported in the summary document shown in the next section, is 274 suspected/confirmed and 226 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 333 cytologically suspected/confirmed and 269 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 seven-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.

#44 Status of the Thyroid Ultrasound Examination Results (May 13, 2022) by Yuri Hiranuma on Scribd

The fourth round
    For the still ongoing fourth round, originally scheduled from April 1, 2018 through March 31, 2020, only 31 more participated in the primary examination between July 1, 2021 and September 30, 2021, with an unchanged participation rate of 62.3%. (Note: 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.)

    Only one person became newly eligible for the confirmatory examination, having received the "B" assessment in the primary examination. Ten newly participated in the confirmatory examination with 2 undergoing FNAC (fine-needle aspiration cytology), and one male, who was age 10 at the time of the 2011 nuclear accident, was diagnosed with suspected thyroid cancer. His third-round result was "B." He is from the FY 2018 municipality and a resident of Nakadori.

   Three (two cases 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 September 30, 2021, the number of suspected or confirmed thyroid cancer cases for the fourth round is 37, of which 32 have been surgically confirmed as papillary thyroid cancer. 

    The previous results from the third round are as follows: 25 with "A" (6 with A1, 13 with A2 cysts, 5 with A2 nodules, and 1 with A2 cysts and nodules), 9 with "B," and 3 with no prior result. 

The fifth round

    The fifth round targets 252,855 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. (It has previously been 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. [Note: 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.]

     As of September 30, 2021, 45,860 participated in the primary examination, including 13,456 new participants, and its participation rate increased from 12.8% to 18.1%, still quite low. Participation rates by age group went up 30-50% at 31.3% in ages 8-11, 20.1% in ages 12-17, and 7.4% in ages over 18. The primary examination results are available for 38,136 (83.2%), and 458 (an additional 167 new cases) were assessed as "B," qualifying for the confirmatory examination. 

   Sixty-three newly participated in the confirmatory examination, 10 underwent FNAC, and 3 (1 male and 2 females) were diagnosed with suspected thyroid cancer. All three are residents of the FY 2020 municipalities. Age and tumor diameter data for the fifth round are available for the first time, and the age range at the time of the accident is shown to be 2 to 12 years, which means someone diagnosed in the fifth round was 2 years old at the time of the accident. Also newly reported were the results of blood tests and urinary iodine.

   Two from the FY 2020 municipalities have been confirmed with papillary thyroid cancer after undergoing surgery.

   In summary, as of September 30, 2021, the number of suspected or confirmed thyroid cancer cases for the fifth round is 6, of which 3 have been surgically confirmed as papillary thyroid cancer. 

   The previous results from the fourth round were released for the first time: 3 with "A" (1 with A1, 1 with A2 cysts, 1 with A2 nodules), 2 with "B," and 1 with no prior result. 

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. The most recent implementation schedule available in English is from September 2020, which was reported to the 41st session of the Oversight Committee and 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.) 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. 

    Note: 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 (an increase here is due to the inclusion of those who were in utero at the time of the accident),  336,667 for the third round, 294,231 for the fourth round, and now 252,855 for the fifth round.

    The results reported this time are from the data up to September 30, 2021, and for the first time the age and sex distribution graph for suspected and confirmed cancer cases is included. Although this fiscal year cycle begins screening in those who were born in FY1996, the results from this cohort is not included here due to a limited number participants. Moreover in FY2022, those born in FY1992 became eligible to participate in the Age 30 Milestone Screening.

     Since the previously reported results as of June 30, 2021, 542 more participated in the primary examination, with total participants being 7,612,  A participation rate slightly increased by 0.6% to 9.3% which is still extremely low. 

    With an addition of 55 participants newly receiving "B" assessment in the primary examination, a total of 414 qualified for the confirmatory examination. Of 328 confirmatory examination participants including 89 added during this report period, 304 have the final results. After FNAC was conducted in 8 individuals (with a total FNAC cases of 25), 4 individuals (2 males and 2 females) were diagnosed with suspected thyroid cancer. Their prior screening results were: 1 with "A" (A2 cyst), 1 with "B," and 2 with no prior screening.

    Thus the number of suspected or confirmed thyroid cancer cases from the Age 25 Milestone Screening increased by 4 to 13. The results from the prior screening are: 2 with "A" (1 with A2 nodule, 1 with A2 cyst), 3 with "B" and 8 with no prior screening.

     No new surgical cases were added, and the number of surgically confirmed thyroid cancer cases remains at 6, including 5 papillary thyroid cancers and 1 follicular thyroid cancer. 

     Note: The FNAC results show a minimum tumor diameter of 6.2 mm, which is 3.2 mm smaller than last reported. This means that newly detected tumors are smaller and thus potential candidates for non-surgical active surveillance. No change in the number of surgical cases seems to support this scenario. (No evidence exists for active surveillance of noninvasive thyroid papillary microcarcinomas in pediatric population, but individuals in the Age 25 Milestone Screening are mostly in their late 20's at diagnosis.) 

    

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 (37 cases): 6 cases with A1, 19 cases with A2 (5 nodules, 13 cysts, and 1 nodule & cyst), 9 cases with B, 3 cases previously unexamined
• Fifth round (6 cases): 1 case with A1, 2 cases with A2 (1 cyst and 1 nodule & cyst),  2 cases with B, 1 case previously unexamined
• Age 25 Milestone Screening (13 cases): 2 cases with A2 (1 nodule and 1 cyst), 3 cases with B, 8 cases previously unexamined