Fukushima Thyroid Examination December 2018: 166 Surgically Confirmed as Thyroid Cancer Among 207 Cytology Suspected Cases

♦Note: This post is likely to be updated with key points from the meeting in the near future.
♦The February 21, 2019 update begins below the embedded file, "The Status of the Thyroid Ultrasound Examination."
♦On April 9, 2019, links to the third round, fourth round, and Age 25 screening reports in Japanese were replaced with links to English versions.

For more detailed information on the Fukushima Thyroid Examination itself, see the September 2017 fact sheet (long version, or e-published PDF)

  • The third round: 3 cases newly diagnosed as suspicious or malignant, and 2 new cases surgically confirmed.
  • The fourth round: No cytology conducted yet as of September 30, 2018.
  • Age 25 Milestone Screening for those born in FY1992: 2 cases diagnosed as suspicious or malignant. No surgery yet.
  • Total number of suspected/confirmed thyroid cancer is now 206 (excluding a single case of benign tumor; 115 in the first round, 71 in the second round, 18 in the third round, and 2 in Age 25 Milestone Screening).
  • Total number of surgically confirmed thyroid cancer cases has increased by 2 to 166 (101 in the first round, 52 in the second round, and 13 in the third round).
The latest overall results including "unreported" cases:
(See this post for the details of the "unreported" cases.)

On December 27, 2018, the 33rd Oversight Committee for Fukushima Health Management Survey (FHMS) convened in Fukushima City, Fukushima Prefecture. Among other information, the Oversight Committee released the latest results (as of September 30, 2018) of Thyroid Ultrasound Examination (TUE) including the third and fourth rounds as well as the Age 25 Milestone Screening for those born in FY1992. Official English translation will be available here in the near future. (Note on April 9, 2019: Official English translation was finally posted here on April 5, 2019.) 

A five-page summary of the first through third rounds, "The Status of the Thyroid Ultrasound Examination," was also released, listing key findings from the primary and confirmatory examinations as well as the surgical information. In particular, any update to the number of surgical cases is reflected in this summary before such information is compiled in the fiscal year update as of March 31. This summary is not translated into English officially, but here's an unofficial translation. 

Updated on February 20, 2019
Other topics covered at this Oversight Committee meeting include:
  1. Publication report of a paper in Scientific Reports.
  2. A report from the Eleventh session of the Thyroid Examination Assessment Subcommittee held on October 29, 2018.
  3. Recommendations by the IARC Expert Group on Thyroid Monitoring after Nuclear Accidents (TM-NUC). (See this post on what TM-NUC is all about.) 
  4. A compilation of surgical and pathological features of 125 thyroid cancer cases.
  5. A revision of the TUE support project provisions.
1. Publication report of a paper in Scientific Reports

   An FMU official reported publication of a paper, "Spatial analysis of the geographical distribution of thyroid cancer cases from the first-round thyroid ultrasound examination in Fukushima Prefecture." (link)  The paper concluded that the thyroid cancer cases detected in the first round are unlikely to be attributable to regional factors, including radiation exposure due to the Fukushima nuclear accident.

2. A report from the Eleventh session of the Thyroid Examination Assessment Subcommittee 

   The subcommittee chair, Gen Suzuki, went over the report including the materials handed out at the October 2018 subcommittee meeting as well as previous meetings. The report (only in Japanese) can be accessed here. (The list of the materials handed out at the subcommittee meeting is available here, and the detailed summary of this subcommittee meeting is included in pages 6-16 of the Japanese article e-published on the Kagaku website.)
   Analyses conducted by FMU on the second round results only include data from those who participated in both the first and the second rounds, consisting of analyses by age groups, regions, the first round results, and the length of time elapsed since the first round screening (aka screening interval). The detection rates of suspected/confirmed thyroid cancer increased with age and the length of screening interval. The screening interval was naturally the longest in the evacuation area and the shortest in Aizu, corresponding to the order of screening in the first round. When the detection rates of "B" test result and suspected/confirmed cancer in the second round were split up by the screening year of the first round (Table 4 on page ①-8 of the report), FY 2011 showed the lowest percentage of the first round "B" among the second round "B" at 19.5%. This was related to the low detection rate of "B" and "C' among the FY 2011 participants in the first round, which in turn was attributed to a unique circumstance of initial chaos and lack of examiners under which the FY 2011 was conducted. 
   Some of the subcommittee members cautioned that interpretation of apparent regional differences in cancer detection rates as dose response must take into consideration regional differences in factors such as participation rates, screening interval, circumstances and results of the first round, and FNAC rates. 
   According to FMU, these analyses were intended to offer to the Subcommittee some materials for reviewing the second round data. This appeared to be an attempt to fulfill the request from the subcommittee members to make data available in actual numbers rather than just percentages in FMU's partial analysis of some of the first and second round data (available only in Japanese here and also included in the report from the 11th subcommittee meeting) released at the 10th subcommittee meeting on July 8, 2018 (described in this post). However, this attempt was still clearly inadequate: Kota Katanoda from the National Cancer Center Japan requested more detailed distribution of tumor diameter in order to evaluate differences in detection rates by the screening year. 
   Subcommittee Chair Suzuki announced that thyroid doses by municipality and age group estimated by UNSCEAR will be used to conduct an analysis of the second round data. Katanoda warned that results from such an analysis should be interpreted with caution due to unadjustable confounders. Suzuki also revealed his intention to eventually shift from a cross-sectional ecological study currently conducted to case control studies in a cohort that has some degree of post-accidental dietary and behavior record (to be used to reconstruct individual thyroid doses).
   Regarding the TUE conducted in a school setting (herein, school screening), it was revealed to have been requested by municipalities and municipal boards of education in order to ensure equal opportunities for participation, lessen families' burden in taking children to the designated TUE facilities, and prevent absence from classes. 

   After Suzuki's reporting on the 11th subcommittee meeting, several points were raised by the oversight committee members. Shoichiro Tsugane from the National Cancer Center Japan remarked that conducting analyses by adjusting for biases and confounding factors is easier said than done. He continued to point out that detection biases were so strong that adjusting any dose response which might be shown for the biases by statistical modeling could be impossible. Noboru Takamura from Nagasaki University brought up uncertainties associated with the UNSCEAR thyroid doses.
   Toru Takano of Osaka University, who is also a subcommittee member (he is the only dual member) and a vocal opponent of the school screening, explained that, in accordance with the Declarations of Helsinki, the adverse effects of the TUE warrant that the school screening be not compulsory. When asked to describe the adverse effects of the TUE, Takano gave examples of psychological distress, commonly experienced by cancer patients, voiced by some patients that have come to see him. Kanae Narui, a clinical psychologist, responded to Takano that such distress was anticipated even before the TUE started, and it is something that can be clinically dealt with psychological care, not something that should be used as a reason to stop the TUE or the school screening. 

Table 1: Detection rates of suspected/confirmed thyroid cancer in the second round by age group

Table 3: Detection rates of suspected/confirmed thyroid cancer in the second round by region

Table 4: Detection rates of suspected/confirmed thyroid cancer in the second round by screening year for the primary examination in the first round

3. Recommendations by the IARC Expert Group on Thyroid Monitoring after Nuclear Accidents (TM-NUC)
   An official from Ministry of the Environment (MOE) presented a Japanese translation of the TM-NUC recommendations, which is actually a translation of an article published in the Lancet Oncology, "Long-term strategies for thyroid health monitoring after nuclear accidents: recommendations from an Expert Group convened by IARC." Translation had been commissioned to the Nuclear Safety Research Association (NSRA), along with some clerical work, by the MOE which fully financed this "project." (Read more on the "birth" of the TM-NUC project in this post.) The entire report, "Thyroid health monitoring after nuclear accidents," issued as "IARC Technical Publication 46" can be accessed from the TM-NUC website or the IARC website (or from this PDF link.) For clarification, the TM-NUC recommendations are not meant to be applied to the TUE already undergoing in Fukushima. 
   As described in this summary, the IARC Expert Group recommends against population thyroid screening, defined as actively recruiting all residents of a defined area to participate in thyroid examinations and subsequent diagnostic or follow-up tests as indicated. The Expert Group recommends a long-term thyroid monitoring program in higher-risk individuals. A thyroid monitoring program is defined as an elective activity including education to improve health literacy, registration of participants, and centralized data collection from thyroid examinations and clinical management. Higher-risk individuals are defined as individuals who received a thyroid dose of 100-500 mGy in utero, childhood, or adolescence. Note that screening is distinguished from monitoring. The recommendations do not preclude lower-risk individuals with lower doses from participating in the monitoring program after fully informed of pros and cons of thyroid examinations.

   Despite the clarification that the TM-NUC recommendations are not meant to evaluate Fukushima's TUE, Tsugane remarked that the recommendations were formed after discussions were carried out by the experts who "learned and understood all that has happened in Fukushima's TUE," and that the considerations included thyroid cancer screening in children and adolescents. The rest of his remarks about high survival rates of childhood thyroid cancer and harms of screening on asymptomatic individuals concluding with a plea to the committee members to "think hard" about the TUE on Fukushima children made it sound as if Tsugane was suggesting the TUE conform to the TM-NUC recommendations.
   However, there are major differences in thyroid cancer management between Japan and western countries that make make reliance on data from western studies tricky. For instance, hemithyroidectomy is the surgical method of choice in Japan for preservation of natural thyroid function unless total thyroidectomy is absolutely called for, and almost all cases undergo extensive lymph node dissection. Whereas in the US, total thyroidectomy and radioiodine treatment is considered the mainstream management, which might lead to high survival rates, but QOL (quality of life) might suffer from lifetime thyroid hormone supplementation as well as side effects of radiation treatment including an increased risk of secondary cancer.
   Use of survival rates as the end point (i.e., as in conventional cancer screening) has been a point of contention during both the oversight committee and the subcommittee meetings, with some members (esp. Takano and Tomotaka Sobue, both of Osaka University) calling Fukushima's thyroid cancer cases "overdiagnosis" and even recommending a switch of diagnostic modalities from ultrasound to palpation based on a high survival rate even when diagnosed after symptoms appear. 
   Other members, including a thyroid surgeon, a pediatrician and a pathologist, have cautioned against relying on survival rates and placed importance on high QOL achieved by early diagnosis and treatment. It was also explained that, given the fact that the TUE was started against the backdrop of the Fukushima nuclear accident, the TUE should not be considered as a conventional cancer screening but as a health examination to assess potential effects of radiation exposure. (Note: This was also stated by Shinichi Suzuki, a thyroid surgeon at FMU, at the 2nd subcommittee meeting in 2014. In Japanese, "cancer screening" and "health examination" are both called "ken-shin" but use different kanji characters for "ken.")
   Another issue with Tsugane's remark about how the experts "learned and understood all that has happened in Fukushima's TUE" is that the information about Fukushima's TUE included in the TM-NUC report appears to be mostly limited to the official TUE results that have been released publicly. Lack of transparency has always been an issue with the TUE data, but we now know the official data does not include any cancer cases diagnosed during clinical follow-up ("unreported cases") or undergoing surgery at non-FMU medical facilities. Thus, TM-NUC could not have "learned and understood all that has happened in Fukushima's TUE," as recognized by Tsugane. (This "recognition" by Tsugane was strange, considering Tsugane's criticism when the existence of the "unreported cases" was revealed. Tsugane stated that any paper written excluding the "unreported cases" would not be able to be accepted by journals as international or scientific paper and that it was scientifically expected for cancer screening data to include all cases diagnosed during a given period.)
   Further, review of some of the academic papers used by TM-NUC as references on the TUE also reveals their conclusions of denying radiation effects are mostly based on analyses of the first round data. This "denial" has to be considered too premature, given the second round data have yet to undergone analyses for potential dose response.

4. A compilation of surgical and pathological features of 125 thyroid cancer cases

   This handout titled "Regarding surgical cases at Fukushima Medical University hospital" is a compilation of clinical information already released and included in the following four references:
   Basically, there is no new information in this report that hasn't been released up to now. It's that all the clinical and pathological information released so far—albeit limited—is complied in one handout with an additional information about TNM and Ex classifications and an anatomical classification of regional lymph nodes as designated in the seventh edition of the Thyroid Cancer Management Guidelines. Chairman Hoshi commented that this report was put together to address repeated requests by the committee member Fumiko Kasuga of the National Institute of Environmental Studies. Kasuga politely thanked for the report, apparently without realizing it does not contain what she has been asking for: an additional set of information such as a more detailed distribution of tumor diameters.
   More information about inconsistencies of the second and third references will be added at the end of the current post.

5. A revision of the TUE support program provisions

   As explained in the July 2018 post, the TUE support program offers reimbursement for out-of-pocket medical expenses (30% copay) incurred while undergoing follow-up observation or medical treatment for thyroid nodules diagnosed during the TUE. The revision, effective December 12, 2018, retroactively removes one of the previous eligibility criteria requiring participation in the confirmatory examination of the TUE at the FMU-authorized medical facilities. This revision, explained in this handout and read aloud by Yoichi Suzuki, chief of prefectural department of Fukushima Health Management Survey, was called for in order to expand eligibility to those receiving medical care outside FMU or FMU-authorized facilities for various reasons. As laid out on the Fukushima Prefecture website, the revised eligibility criteria are as simple as 1) participation in the TUE and 2) receiving medical care for thyroid nodular lesion(s) at medical facilities. The criterion 1) can even be waived under compelling circumstances such as evacuation. 
   The TUE support program offers financial support in exchange for some clinical information. The revision also calls for an additional collection of clinical information, such as the presence of distant metastasis, which is necessary for continuous support.
   In Fukushima Prefecture, children aged 18 or younger receive free medical care until the end of fiscal year when they turn 18. The TUE support program excludes those receiving free medical care from Fukushima Prefecture or those on welfare. There are also municipal and prefectural medical expense assistance programs with various coverage and age limits throughout Japan, so those who moved out of Fukushima Prefecture receiving such assistance will not qualify for the TUE support program, either.
   There were questions from the committee members regarding the actual number of thyroid cancer cases in relation to the statement made by Suzuki to the December 13, 2018 Fukushima Prefectural Assembly. Suzuki stated that all 233 receiving payments from the TUE support program had thyroid cancer, whereas it had previously been reported that 233 received payments including 82 that underwent surgery and 77 of 82 were confirmed with thyroid cancer. This discrepancy caused a confusion, leading some to criticize "underreporting." Suzuki never said his statement at the prefectural assembly was incorrect, but he did clarify that there were indeed 77 cancer cases.

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Fukushima Thyroid Examination April 2019: 168 Surgically Confirmed as Thyroid Cancer Among 212 Cytology Suspected Cases

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