Fukushima Thyroid Examination June 2016: 57 Cases Suspicious or Confirmed of Thyroid Cancer in the Second Round Screening

131 Thyroid cancer cases confirmed in Fukushima as of March 31, 2016--101 in the first round and 30 in the second round (Total of 172 cases including suspected cancer cases--115 in the first round and 57 in the second round).


The 23rd Prefectural Oversight Committee for Fukushima Health Management Survey convened in Fukushima City, Fukushima Prefecture, on Monday, June 6, 2016. 

Among other information, the Oversight Committee released the latest results (March 31, 2016) of the Full-Scale thyroid examination, or the second round screening, which was conducted over a two-year period from April 2014 to March 2016. The second round screening is essentially ongoing in terms of the confirmatory examination, so the results are not complete.

For the Initial (Preliminary Baseline) Screening, or the first round screening, the updated, corrected version of the results was released. 

There has been no updated information on clinicopathological details of the surgical cases since August 2015 that showed 74% lymph node metastases post-surgically. The most recent publication in Thyroid by Fukushima Medical University covering the first round screening results as of the August 2015 report only includes older information from the November 11, 2014 Thyroid Examination Evaluation Subcommittee meeting available here.

An official English translation of the results is available here. The narrative below contains some information gathered from the live webcast of the Oversight Committee meeting and the subsequent press conference. 

Overview
As of March 31, 2016, there are 6 more cases with malignancy or suspicion of malignancy from the second round, for a total of 172 (173 including the single case of post-surgically confirmed benign nodule). The number of surgically confirmed cancer cases, excluding the aforementioned case of benign nodule, now totals 131 (101 from the first round and 30 from the second round), and the remaining 41 (14 from the first round and 27 from the second round) await surgical confirmation. Since the last results were released, 14 additional cases from the second round have been operated on and confirmed as papillary thyroid cancer by post-surgical pathological examination of the resected thyroid gland tissue.

For the first time, there was a case of age 5 (male) at the time of the accident. This did not get a special mention during the committee meeting, but various domestic and international experts have used the absence of age 5 or younger at exposure as one of the reasons why Fukushima cancer cases were unlikely to be related to radiation exposure. There were a few questions during the press conference regarding how the committee perceived this particular case. The answer was evasive: the single case of age 5 at exposure would not mean much, especially without the exposure dose information.

Initial (Preliminary Baseline) Screening (a.k.a. the first round)
The first round targeted about 368,000 individuals who were age 18 or younger, residing in Fukushima Prefecture at the time of the Tokyo Electric Fukushima Daiichi nuclear power plant accident on March 11, 2011. There were 300,476 actual participants in the primary examination, giving rise to the participation rate of 81.7%. As of March 31, 2016, there are 116 cases with malignancy or suspicion of malignancy, including a case of the post-surgically diagnosed benign nodule: 102 underwent surgery and 101 were confirmed with thyroid cancer (100 papillary thyroid cancer and 1 poorly differentiated thyroid cancer). 

An additional, updated information from the first round
Details of the three cases orally presented previously were revealed: 2 females (ages 13 and 18) and 1 male (age 17) with their municipalities of residence including Yabuki Town, Hanawa Town, and Aizumisato Town, all FY2013 target municipalities.

There are about 160 who did not participate in the confirmatory examination, but about 60 went through the second round examination and have been reclassified as the A assessment.

Another notable update for the first round was the number of poorly differentiated thyroid cancer, which was decreased from 3 to 1 in accordance with the November 2015 revision of Japan's unique thyroid cancer diagnostic guidelines. No specific details were given regarding the reclassification of 2 (1 each from FY2011 and FY2012) of the 3 cases of poorly differentiated thyroid cancer as papillary thyroid cancer. According to some of the abstracts from the Japan Association of Breast and Thyroid Sonology meeting in late May 2016, it seems that according to the previous guidelines, poorly differentiated thyroid cancer was diagnosed if there was even a small portion of tumor showing poorly differentiated features, whereas the new guidelines requires poorly differentiated features to compose more than 50% of the tumor.

Full-Scale Screening (a.k.a. the second round)
To be conducted every 2 years until age 20 and every 5 years after age 20, the second round screening additionally targets those who were born in the first year after the accident, eventually aiming to examine 381,286 individuals in a 2-year period. As of March 31, 2016, 267,769 have participated in the primary examination of the second round at the participation rate of 70.2%. 256,670 have received confirmed results of the primary examination, and 2,061 turned out to be eligible for the confirmatory examination. 

The confirmatory examination is only two-thirds completed. Of 1,345 who actually underwent the confirmatory examination, 1,242 received confirmed results including 169 that underwent fine-needle aspiration cytology (FNAC). 57 cases had FNAC results suspicious for cancer. Confirmation of thyroid cancer requires pathological examination of the resected thyroid tissue obtained during surgery. As of March 31, 2016, 30 underwent surgery and all 30 were confirmed to have papillary thyroid cancer.

Newly diagnosed cases in the second round
In the second round, 6 cases were newly diagnosed by FNAC to be malignant or suspicious of malignancy. There were 4 males (age at exposure: 5, 8, 14 and 15) and 2 females (age at exposure: 10 and 15). Their places of residence at exposure include 4 municipalities: FY 2014 target municipalities such as Okuma Town and Koriyama City (2 cases); and FY 2015 target municipalities such as Iwaki City (2 cases) and Kagamiishi Town. (In the first round, Okuma Town was included in the FY 2011 target municipalities; Koriyama City in the FY 2012 target municipalities; and Iwaki City and Kagamiishi Town in the FY 2013 target municipalities). 

Cytology results show the 5-year-old (age at exposure) to be from FY2015 screening. His municipality is deduced to be Iwaki City based on the confirmatory examination implementation status by municipality (not translated in this post). Of 44,143 Iwaki City residents who participated in the second round screening, 322 were eligible for the confirmatory examination. Only 105 have actually participated in the confirmatory examination as of March 31, 2016, and 74 of them have confirmed results. Thus, more confirmatory examination results are expected from Iwaki City, the largest of the FY2015 target municipalities. 

Prior diagnostic status of the cases newly diagnosed in the second round
Of 57 total cases with malignancy or suspicion of malignancy in the second round, 28 were A1, 25 were A2, and 4 were B in the first round. (In the 6 cases with malignancy or suspicion of malignancy reported this time, 3 each were classified as A1 and A2 in the first round). 

28 cases that were A1 in the first round screened suspicious for malignancy in the second round. This would appear to be a new onset after the first round since A1 cases by definition have no ultrasound findings of cysts or nodules.

In 25 cases that were A2 in the first round, it is not clear how many were cysts, but 15 of 22 were cysts in the last report. Thus the majority of the second round cases appeared to have developed thyroid cancer in 2 to 3 years since the first round.


First Round or Initial Screening (October 2011 - April 2015)

Total number targeted: 367,672
Number of participants in primary examination: 300,476
Number with confirmed results: 300,476

• A1   154,607 (51.5%) (no nodules or cysts found)
• A2   143,575 (47.8%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
• B        2,293   (0.8%) (nodules ≧ 5.1 mm or cysts ≧ 20.1 mm)
• C               1   (0.0%) (requiring immediate secondary examination)

(Note: Cysts with solid components are treated as nodules).

Number eligible for confirmatory (secondary) examination: 2,294

Number of participants in confirmatory (secondary) examination: 2,128

Number with confirmed results : 2,086

Number of fine-needle aspiration cytology (FNAC): 545

Number suspicious or confirmed of malignancy: 116 (including one case of benign nodules)

Number with confirmed tissue diagnosis after surgery: 102

• 1 benign nodule
• 100 papillary thyroid cancer
• 1 poorly differentiated cancer

Second Round or Full-Scale Screening (April 2014 - March 2016)

Total number targeted: 381,286

Number of participants in primary examination: 267,769

Number with confirmed results: 256,670

• A1   102,870 (40.1%) (no nodules or cysts found)
• A2   151,739 (59.1%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
• B        2,061   (0.8%) (nodules ≧ 5.1 mm or cysts ≧ 20.1 mm)
• C              0   (0.0%) (requiring immediate secondary examination)

(Note: Cysts with solid components are treated as nodules).

Number eligible for confirmatory (secondary) examination: 2,061

Number of participants in confirmatory examination: 1,345

Number with confirmed results: 1,242

Number of FNAB: 169

Number of cases with malignancy or suspicion of malignancy: 57

Number with confirmed tissue diagnosis after surgery: 30

• 30 papillary thyroid cancer

Unofficial translation of selected tables

Full-Scale Screening

Table 1. Primary examination coverage as of March 31, 2016

Table 2. Number and proportion of children with nodules/cysts as of March 31, 2016

Table 3. Participation rates by age group as of March 31, 2016

Table 4. Comparison with the Initial (Preliminary Baseline) Screening as of March 31, 2016

Note 1: Top line refers to the results of the Preliminary Baseline Screening for confirmed results of the Full-Scale Screening.
            It is not the breakdown of the total Preliminary Baseline Screening results, 300,476.
Note 2: Top line refers to the breakdown of the Full-Scale Screening results in a given category of the Preliminary Baseline Screening results. 

            Bottom line shows the proportion in %.

Table 5. Confirmatory testing coverage and results as of March 31, 2016

Table 6. Cytology results (including information from Appendix 6: Number of surgeries among cases with malignancy or suspicion of malignancy) as of March 31, 2016

Figure 3. Distribution of cases with malignancy or suspicion of malignancy by age (as of March 11, 2011) and sex (females in white and males in gray)

Figure 5.  Estimated external effective doses of those who submitted basic survey questionnaire as of March 31, 2016 (females in white and males in blue) 

Initial (Preliminary Baseline) Screening
(updated information marked with yellow highlights)

Table 1. Primary examination results (final results from October 9, 2011 to April 30, 2015)

Table 2. Number and proportion of children with nodules/cysts

Table 3. Confirmatory testing coverage and results as of March 31, 2016

Table 4. Cytology results (including information from Appendix 7: Surgical cases of suspicious or malignant cases) 

Table 9. Proportion of B or C test results, and suspicious or malignant cases                   As of March 31, 2016

Note 10: Excluding duplicates.

Note 11: Excluding unconfirmed results. 

Note 12: The number of FNAC, out of (c), including those who were reclassified as A1 or A2.

Note 13: Excluding one suspected case found benign after surgery.

Note 14: Tamura City, Minamisoma City, Date City, Kawamata Town, Hirono Town, Naraha Town, Tomioka Town, Kawauchi Village, Okuma Town, Futaba Town, Namie Town, Katsurao Village and Iitate Village

Note 15: Fukushima City, Koriyama city, Shirakawa City, Sukagawa City, Nihonmatsu City, Motomiya City, Koori Town, Kunimi Town, Otamamura Village, Kagamiishi Town, Tenei Village, Nishigou Village, Izumizaki Village, Nakajima Village, Yabuki Town, Tanagura Town, Yamatsuri Town, Hanawa Town, Samegawa Village, Ishikawa Town, Tamakawa Village, Hirata Village, Asakawa Town, Furudono Town, Miharu Town, and Ono Town

Note 16: Iwaki City, Soma City, Shinchi Town

Note 17: Aizuwakamatsu City, Kitakata City, Shimogo Town, Hinoemata Village, Tadami Town, Minamiaizu Town, Kitashiobara Village, Nishiaizu Town, Bandai Town, Inawashiro Town, Aizubange Town, Yugawa Village, Yanaizu Town, Mishima Town, Showa Village, and Aizumisato Town

"Strict" Management of the Fukushima Health Management Survey Data by Fukushima Medical University

The Interim Report released in March 2016 by the Oversight Committee for Fukushima Health Management Survey called for the need to establish the rules of management and provision of the data so it can be widely utilized by domestic and international experts. Accordingly, the Subcommittee to Review Provision of Data for the Purpose of Academic Research met in Fukushima City, Fukushima, for the first time on May 31, 2016. Subcommittee members were selected by the Fukushima prefectural government in order to address the role of the subcommittee in establishing technical rules in provision of data and include specialists in epidemiology, information technology, law, and legal sociology. Also included are members of the Oversight Committee for Fukushima Health Management Survey, Shoichiro Tsugane and Hokuto Hoshi, and the Health Survey Support Department Head and the Department of Epidemiology Chair at Fukushima Medical University, Tetsuya Ohira, representing the Fukushima Health Management Survey. Noteworthy was the absence of a medical ethicist.

The subcommittee meeting, streamed live online by independent journalists, revealed important facts that warrant sharing with the English-speaking community.

First, even those of us who have been following activities of the Fukushima Health Management Survey from the beginning did not realize Fukushima Prefecture has actually commissioned academic presentation and paper publication of the data to Fukushima Medical University in addition to collection of data. Apparently, data analysis is one of the commissioned tasks assigned to Fukushima Medical University, and as a result, end products of data analysis such as presentations and published papers are considered part of the commissioned tasks. 

(Note: It is a public knowledge that Fukushima Medical University is commissioned by Fukushima Prefecture to conduct the Fukushima Health Management Survey using the 78.2 billion yen "Fukushima Resident Health Fund" established in late 2011 by the Japanese government. However, it might not be as well known that the 78.2 billion yen came from the Ministry of Economy, Trade and Industry, whose Agency for Natural Resources and Energy is tasked with promoting construction of nuclear power plant facilities in Japan via its Nuclear Facilities Development and Nuclear Fuel Cycle Industry Division of the Electricity and Gas Industry Development Department).

Second, it became apparent that the Fukushima Medical University has such strict management guidelines for the Fukushima Health Management Survey data that there is tight control over presentation and publication of the analyzed data via an internal peer review process which approves or disapproves the work. 

For information, the purposes of the Fukushima Health Management Survey are stated on the website of the Radiation Health Science Center: 

     "The primary purposes of this survey are to monitor the long-term health of residents, promote their future well-being, and confirm whether long-term low-dose radiation exposure has health effects."

*****

According to Ohira's statements, summarized below and shown in the video recording of the subcommittee meeting (from 25 minutes 57 seconds, in Japanese), this is what Fukushima Medical University researchers have to go through: 

Those interested in analyzing data would have to submit a request for data analysis specifying the type and purpose of the analysis. The request is then examined by the review committee. If the review committee deems appropriate, the data is provided to the applicant who signs an agreement on data handling. Thus the data is strictly managed. When it comes to presenting the analysis at an academic meeting or publishing the analysis, another request for presentation must be filed with the review committee. The presentation or publication of the analysis can only proceed if the review committee approves it as appropriate. 



A question was posed by a Fukushima University professor and legal sociologist, Hiroyasu Shioya, 

"For the third party use, would the review be a matter of formality or more substantial?"

Ohira answered,

"At the Radiation Medical Science Center for the Fukushima Health Management Survey at Fukushima Medical University, the content (substance) of the analysis itself is examined. In the case of publication of a paper, we conduct what is called an internal peer review, where the paper is distributed to reviewers for examination of the content. Then it is further discussed at the review committee and approved if it is determined appropriate."

Chair of the Subcommittee to Review Provision of Data for the Purpose of Academic Research, Shoichiro Tsugane, wondered how the third-party use review might actually proceed, indicating that would be a future topic of the subcommittee.

A question arose to the viewers' mind as to what is considered "appropriate" by the review committee and who constituted such committee. Answers were found in a document distributed at the February 15, 2016 Oversight Committee Meeting by the Prefectural Department of Fukushima Health Management Survey describing the details of the review committee. 

In summary, any research conducted at Fukushima Medical University must be approved by the Ethics Review Committee as well as the Conflict of Interest Committee. Then, within the Radiation Medical Science Center for the Fukushima Health Management Survey, there is a special review committee, the Review Committee for the Use and Analysis of the Fukushima Health Management Survey Data (referred to as "the Review Committee" hereafter).  Below is a translation of page 4 of the document.

**********

Review procedures for research at Fukushima Medical University

Procedures within Fukushima Medical University

1. Ethics Review Committee (description not translated)
2. Conflict of Interest Committee (description not translated)

Procedures within the Radiation Medical Science Center for the Fukushima Health Management Survey

3. Review Committee for the Use and Analysis of the Fukushima Health Management Survey Data

Reviews appropriateness in the use, analysis, and report of the Fukushima Health Management Survey data.

(1) Eligibility for application
a. Fukushima Health Management Survey expert committee members 
b. Equivalent to the above, with approval by the expert committee

(2) Items to be reviewed
a. Study title, applicant name
b. Type and range of data to be used
c. Purpose of data use
d. Plan for analysis
e. How the analytical result will be publicized
f. Items regarding the use and storage of data

(3) Review criteria
a. Whether the use and report of data will be appropriate according to the Report of Review Committee Regarding Handling of Research and Development Results (Ministry of Education, Culture, Sports and Technology, May 20, 2002).
b. Whether the use follows one of the purposes of the Fukushima Health Management Survey, "to monitor the long-term health of residents."
c. Whether there is any problem if data is used, analyzed and reported according to the review application.
d. Whether there is any problem with qualifications and credentials of the person handling data.
e. Whether data is properly handled.
f. Any other issues with data use.

(4) Review Committee members 
Chair: Executive Director of the Radiation Health Science Center
Members: Deputy Directors, Department Heads, Division Chiefs, Deputy Administrative Director (in charge of reconstruction) of the Radiation Health Science Center; others considered necessary by the Review Committee

**********

According to the information provided on the Japanese website and English website of the Radiation Medical Science Center, Chair of the Review Committee is Masafumi Abe, executive director of the Radiation Medical Science Center for the Fukushima Health Management Survey, and a vice president of Fukushima Medical University.

Below are the Review Committee members whose names and titles are publicly available on the Japanese website. 

Vice Directors: Koichi Tanigawa, Shunichi Yamashita, Kenji Kamiya.
Department Heads: Akira Ohtsuru (Thyroid Examination Department), Masaharu Maeda (Health Survey Department), and Tetsuya Ohira (Health Survey Support Department)

(Note: Names of the above individuals often appear as co-authors of papers published using the Fukushima Health Management Survey data, such as this, this, and this.

***********

Page 3 of the document shows a flow chart of the review procedures at Fukushima Medical University. Use of any data outside the Fukushima Health Management Survey, including the clinical data, only goes through steps 1 and 2, ethics review and conflict of interest review. Use of the Fukushima Health Management Survey data additionally goes through step 3, with details outlined above, except that the review process is different for the publicized data and the unpublicized data.

Use of the publicized data can be requested through the Review Committee in three ways: use, use and academic presentation, or use and academic paper writing. A request for use alone is simply approved or disapproved. If a request for an academic presentation using the publicized data is approved by the Review Committee, the applicant must report back to the Review Committee whether the presentation was accepted at the academic meeting or not. If a request for writing an academic paper using the publicized data is approved by the Review Committee, the completed paper must go through an internal peer review followed by examination of the content at the Review Committee before the paper is approved to be published. 

The review process for use of the unpublicized data is more rigorous. After the application to use and analyze the unpublicized data is approved by the Review Committee, another request must be filed for the result of the analysis to be presented at an academic meeting. If the Review Committee approves the request, the applicant must report back whether the presentation was accepted or not. If the applicant wishes to write a paper using the analyzed result of the unpublicized data, a request must be filed before writing the paper. If the Review Committee approves the request, the paper can be written. Once complete, the paper goes through an internal peer review followed by examination of the content at the Review Committee before the paper is approved to be published (just as in the case of the paper using the publicized data).

**********

Comment: The extent that the data use is "managed" seems extraordinary. Specifically, one of the review criteria regarding whether the use follows the purpose of the Fukushima Health Management Survey, "to monitor the long-term health of residents," is unique to this review process. However, exactly how this is determined and applies as a criterion is unclear. During the Subcommittee meeting, "promotion of health and the well-being of residents" was mentioned multiple times by various committee members as the primary purpose of the Fukushima Health Management Survey and as the reason to guard the data so closely. Certainly, one could imagine the "misuse" of data, as internally determined by the Review Committee, might be detrimental to the well-being of someone--whoever that might be. 

This unusually strict management of data raises questions such as: neutrality of the internal review of academic papers which list the Review Committee members as co-authors; potential biases in the conclusion of the academic presentation or paper; and missed opportunities in pursuing scientific knowledge of health effects of radiation exposure in Fukushima residents. 

What the Subcommittee decides on the third-party use of the data is to be closely followed.

Response to the Chicago Tribune Editorial "The children of Fukushima: When medical tests mislead"

The following is a letter to the Editor for the Chicago Tribune editorial, "The children of Fukushima: When medical tests mislead." The letter was submitted through the online form on April 19, 2016, but there has been no response from Chicago Tribune. (Brevity of the content is due to the 400-word limit for letters).

*****

Dear Editor,

The March 25, 2016 Chicago Tribune editorial, “The children of Fukushima: When medical tests mislead” is misleading on its own regarding the childhood thyroid cancer situation in Fukushima Prefecture, Japan.

Differences in cancer rates by distance from the accident site and contamination levels may not be obvious, but an epidemiological analysis by Tsuda et al. (http://journals.lww.com/epidem/Fulltext/2016/05000/The_Authors_Respond.37.aspx) found a dose response tendency with proximity to the accident site after adjusting for the length of time between the accident and the time of screening. It is also important to remember only 1,080 children had their thyroid exposure doses directly measured and that is only 0.36% of 300,000 children who underwent thyroid ultrasound examination. Taken under high background levels, the doses are far from being accurate.

Children younger than age 5 showed an increased rate of thyroid cancer beginning at 4-5 years after the Chernobyl accident, so the first 3 years after the Fukushima accident, covered by the completed first round screening, would not expect to see that age group affected. The first cancer case was diagnosed about 17 months after the accident, not within a year, and some of these early cases might have been the result of radiation exposure promoting the growth of latent cancer that might not have become large enough to be detected until much later in life if unexposed to radiation.

Comparison with three other prefectures where one cancer case was diagnosed in 4,365 subjects is invalid as its small sample size lacks the necessary statistical power. The Korean screening is in adults and should not be compared with children.

It is true that unnecessary medical testing can lead to overdiagnosis and overtreatment, but the clinical information provided by Fukushima Medical University, such as metastasis and physical proximity of tumor to other vital structures, validates surgical interventions for the majority of the operated cases in Fukushima. Thyroid cancer is believed to grow slowly, but 80% of thyroid cancer cases discovered in the ongoing second round screening had no suspicious findings in the first round screening only 2-3 years earlier.

It is not just a cancer death but cancer diagnosis itself that is concerning for patients and their loved ones, and the causality should not be prematurely prejudged. A lesson of the Fukushima children may be the importance of conducting a timely and adequate collection of the exposure data and a comprehensive evaluation of data in a transparent and unbiased manner.

Yuri Hiranuma, D.O.
Member, Radiation and Health Committee
Physicians for Social Responsibility

Thyroid Cancer in Fukushima Children: When the Language and Information Gaps Mislead

With the year 2016 marking the passage of five years since the Fukushima nuclear accident, many writings—articles, editorials, academic papers—have been released reflecting on the first five years after the accident. Some of the writings address a psychosocial aspect of the accident such as “problems” caused by the stress of evacuation and the “unwarranted” fear of radiation, dismissing the potential health effects of radiation exposure, even ignoring the science. Others focus on the alleged withholding of medical data by authorities, speculating on the health effects of the Fukushima accident reaching even the United States. 

Official data and information available in English are often limited and biased. Transparency and impartiality of such information, released by the government and international agencies, can be influenced by ulterior motives other than public health protection. However, without a fluency in Japanese and an ability to navigate through and comprehend the mass of official and unofficial information only available in Japanese, it may not become obvious that the transmission of accurate information is indeed hindered by the language barrier.

Furthermore, followers of numerous government committee meetings regarding the health effects of the Fukushima nuclear accidents—most of them live streamed on the Internet—have witnessed a systematic underestimation of health effects due to low-dose radiation exposure, with the claim of the outdated and unscientific 100 mSv threshold discourse. Despite concerns from local medical associations, potential health effects in prefectures adjacent to Fukushima Prefecture were dismissed, as if the radioactive plume was blocked by an invisible wall at prefectural borders. This is a far cry from the precautionary principle that should be in place for the protection of public health. 

Consider the Japanese government’s haste to return evacuees to their still contaminated hometowns. This must be done so things appear “back to normal” for the purpose of recovery (mostly economic), even though it is clearly impossible to decontaminate a whole community in a natural setting of mountains and forests. Radiation doses of returned residents are to be monitored to keep an additional exposure dose below the regulatory limit. (But how good is it to know what your exposure dose is after the fact?) 

In essence, the health effects by the Fukushima nuclear accident are being maximally minimized. 

One of the most controversial topics about the health effects of the Fukushima nuclear accident is the thyroid cancer cases detected in Fukushima children as a result of the thyroid ultrasound screening. Most of the English writings on this topic accept, at face value, certain claims made by Fukushima Medical University as well as Japanese government officials in order to dismiss any connection between the Fukushima thyroid cancer cases and radiation. 

Below, some items in the March 25, 2016 editorial in Chicago Tribune, “The children of Fukushima: When medical tests mislead,” are addressed to point out the misleading information that is widespread even amongst the academic circle. 


1. There is no regional difference of thyroid cancer occurrence.

The March 25, 2016 Chicago Tribune editorial states:

“Children living closer to the accident in areas of greatest contamination had no greater rate of early cancer than those living farther away.”

This essentially refers to the lack of dose response, but it might depend on how the prefecture is divided into regions. 

According to the official data by Fukushima Medical University (FMU) and Fukushima Prefecture in the final report of the first round screening [1], no regional difference was reported based on the comparison amongst 4 regions—one region including 13 municipalities with the highest dose and the evacuation zone, and three other geographically-divided regions. However, topography can vary even within the same geographical region, potentially affecting the flow of the radioactive plume. In other words, regional divisions like this might mask critical differences.

On the other hand, the biggest surprise in the official comparison was the Aizu region in western part of Fukushima Prefecture where the prevalence rate of 32.6 per 100,000 was very close to the prevalence rate in the highest dose area, 33.5 per 100,000. (See the second row from the bottom in Table 9). 

The Aizu region supposedly received very little contamination owing to the mountain range to its east, and the officials seem to attribute the higher-than-expected prevalence to the screening activity. According to this logic, other uncontaminated areas of Japan might have similar prevalence. In fact, thyroid ultrasound screening of 4,365 subjects in three other prefectures—Yamanashi, Aomori and Nagasaki—called the three-prefecture study [2] in short, revealed about the same frequency of ultrasound findings such as cysts and nodules as Fukushima, and one case of papillary thyroid cancer was diagnosed in the follow-up study [3].  Very little discussed are the limitations of this study, such as a small sample size leading to a bigger uncertainty, and different age and gender distributions (no age 0-2 and more female adolescents) than Fukushima.

If the three-prefecture study is indeed a proof of screening effects in Fukushima, then it can be deduced that similar prevalence might be found in the rest of Japan. Judging from the clinical information provided by Shinichi Suzuki, a thyroid surgeon at FMU, the vast majority of the operated cases in Fukushima had surgical indications, i.e. required surgery, such as the metastasis and proximity to vital structures, even in the absence of subjective symptoms at the time of diagnosis. Then, it logically follows that there may be other such cases outside Fukushima. However, no attempt is made to conduct a nationwide survey for fear of causing detriments to asymptomatic individuals through unnecessary medical tests and treatments.

In October 2015, the Okayama University team headed by an environmental epidemiologist and public health specialist, Toshihide Tsuda, published in Epidemiology the first epidemiological analysis of the publicly available Fukushima thyroid cancer data [4]. Tsuda et al. first divided the entire Fukushima Prefecture into 3 areas by the year of screening and subdivided them into 9 districts based on the population size, enabling a statistical analysis. 

For external comparison, they calculated for each area/district the incidence rate ratio from the prevalence rate assuming a latency period of 4 years. The calculated incident rate ratios showed thyroid cancer occurrence in some regions were 30 to 50 times the expected rate. Tsuda et al. concluded the excess occurrence was beyond what could be explained by screening effect. Internal comparison did not appear to show dose response amongst the 3 regions by the screening year, which supposedly represented the degree of contamination. 

However, when the data (updated to June 30, 2015) was adjusted for “latency” or the length of time elapsed between the accident and time of screening in their response to letters to the editor [5], a dose response tendency showed up with higher prevalent odds ratios in districts closer to the Fukushima Daiichi nuclear power plant.

Other points to keep in mind include the fact the dose estimation is far from perfect with insufficient direct measurements of the thyroid dose and that the soil contamination does not necessarily reflect the amount of radioactive plume that was in the air at the time of exposure, and that the cesium soil deposition does not necessarily correlate with the amount of radioactive iodine that might have been inhaled or ingested.

A small number of measurements conducted in some 1080+ children aged 0-15 from three municipalities—small considering there were over 360,000 children aged 18 or younger in Fukushima Prefecture at the time of the accident—were ladened with technical issues such as high background radiation levels. The March 30, 2011 internal document, a correspondence from the Emergency Response Center to the Nuclear Safety Commission [6], states how 11 highest readings, taken in Iwaki City, were adjusted to yield lower thyroid equivalent doses as shown in the table below. 
    

From left of the table, column 1 shows measurement dates of March 26 or March 27, 2011. Columns 2 and 3, blacked out for privacy protection on the original document, correspond to the identification number and age of the subject, respectively. Column 4 shows the actual reading ranging from 0.22 μSv/h to 0.27 μSv/h. Columns 5 and 6 correspond to the net measurement after subtraction of the average air dose in μSv/h as the background level in and the resultant thyroid equivalent dose in mSv, respectively. Columns 7 and 8 correspond to the net measurement in μSv/h after subtraction of the measurement at the clothed shoulder as the individual background level and the resultant  thyroid equivalent doses in mSv, respectively. 

For example, in the first subject with the actual measurement of 0.22 μSv/h, the net measurement went down from 0.05 μSv/h to 0.04 μSv/h and the thyroid equivalent dose went down from 19 mSv to 7.1 mSv. For subject 8 with the highest reading of 0.24 μSv/h who had the highest thyroid equivalent dose of 43 mSv before the adjustment, using the individual background level taken at the clothed shoulder reduced the thyroid dose to 25 mSv. 

The problem with using the measurement taken at the clothed shoulder is the potential contamination on clothing might lead to a smaller net measurement. For instance, if the skin and the clothing have the same amount of radioactive contamination, subtracting the measurement of clothing from the measurement of the thyroid will yield the net measurement of zero, but this may not reflect the actual thyroid measurement. 

Despite its limitations and the potential underestimation, the so-called 1080 survey data is considered to represent the exposure dose of Fukushima children, and it seems to be widely accepted by overseas researchers who rely on information published in peer-reviewed English language journals that the maximum thyroid dose in Fukushima children was 35 mSv. Yet there are many other children who might have been exposed to higher doses but never had thyroid doses measured. For instance, children from non-evacuation zone led regular daily activities without any protective measures in the absence of any warnings about the approaching radioactive plume. Many were outside unprotected, and there is no way to accurately estimate the exposure doses for them.

In addition, the Ministry of the Environment expert committee chaired by Shigenobu Nagataki heard presentations by experts who actually conducted the 1080 survey who acknowledged that they thought the survey was only preliminary and more detailed measurements would be conducted if necessary. In the end, officials never conducted a more detailed thyroid survey measurement in a boy from Iwaki City who registered the highest thyroid measurement, 35 mSv, for fear of “scaring the family and the community” upon a recommendation [7] of Yoshiharu Yonekura, the chair of the National Institute of Radiological Sciences as well as the current chair of UNSCEAR. (Incidentally, Iwaki City, not one of the evacuated municipalities, was hit by the radioactive plume when the wind turned south, but the lack of precipitation afterwards prevented a heavy ground deposition of radioactive substances as in Iitate Village).  

Maintaining a sense of security and preempting panic and mass chaos took precedence over accurate recording/reporting of exposure doses. 

2. Age distribution

The March 25, 2016 Chicago Tribune editorial states:

“Younger children and infants, whose thyroids are more likely to be affected than those of older children, did not show an expected higher rate of abnormal findings.”

It is well known that beginning about 4 years after the Chernobyl accident, an increased number of thyroid cancer cases were detected in children in Russia, Belarus and Ukraine who were infants at the time of the accident. In the first 3 years after the Fukushima accident, the youngest cancer case was 6 years old at the time of the accident according to the data published so far. This is depicted in the age distribution graph in a letter to the editor of Thyroid [8].

The top panel shows the number of thyroid cancer cases by age in Ukraine in two different time periods: 1986-1989 (black) and 1990-1993 (dark gray). The 1986-1989 age distribution resembles the graph in the bottom panel showing the first three years in Fukushima (light gray). 

Japanese authorities, notably Shunichi Yamashita, have referred to this resemblance to make certain points: 1) Fukushima’s age distribution in the first three years resembles the first three years in Chernobyl during the latency period when radiation-induced thyroid cancer was still growing, and thus the Fukushima cases are not related to radiation; 2) Fukushima’s thyroid cancer cases are not related to radiation exposure since they do not include younger children under age 4 or 5. 

It might be this second point that is addressed by author(s) of the Chicago Tribune editorial. However, this cannot be a valid claim since a large number of cancer cases in younger children under 4 or 5 were not seen until 4 to 5 years after the Chernobyl accident, and it should not be compared to the first 3 years in Fukushima. Yet this misguided direct comparison is done by none other than the authoritative researchers in radiation-induced thyroid cancer such as Williams [9] and Wakeford [10].

(From: Williams D, Thyroid Growth and Cancer. Eur Thyroid J 2015;4:164-173)

(Wakeford J. Radiol. Prot.  36  (2016) E1)

It remains to be seen whether a similar increase in thyroid cancer cases in younger children will be seen in Fukushima from the fourth year onward, when the complete results of the ongoing second round screening covering the fourth and fifth post-accident years become available, probably later in 2016.


3. Latency issues

The Chicago Tribune editorial states:

“Some cancers were observed less than a year after the meltdown. It generally takes years for thyroid cancer to develop after radiation exposure.”

For clarification, the first case suspicious for thyroid cancer in Fukushima children was reported in September 2012, or 18 months after the accident, not less than a year. 

A traditional view of carcinogenesis is a multi-stage process of mutations transforming normal cells into cancer cells through initiation, promotion, and malignant transformation , and it is considered to take a long time. Radiation-induced thyroid cancer in children is thought to take several years to develop after DNA damage is “initiated” by radiation,  which might explain the increase in thyroid cancer cases 4-5 years after the Chernobyl accident in children who were younger than age 5 at the time of the accident.

On the other hand, there were higher-than-expected number of thyroid cancer cases diagnosed in Belarus the first year after the 1986 Chernobyl accident [12,13].

As a complete carcinogen, radiation can affect all stages of carcinogenesis. Radiation can also affect the so-called “cancer niche,” or the tumor microenvironment necessary for clinical development of cancer [14]. In other words, radiation might facilitate the growth of pre-existing precancerous cells or latent cancers through promotion as well as creation and/or expansion of the cancer niche.

It might then be feasible to consider that some of these early cases manifested because exposure to radiation affected the growth of pre-malignant cells or pre-existing cancer. This might not be considered “radiation-induced” in the field of radiobiology, but it can be considered as the effect of radiation nonetheless.


4. Overdiagnosis?

Yet, the reason for detection of so many thyroid cancer cases in the first 3-4 years after the Fukushima accident is not completely clear. Is it because of the screening activity alone as claimed by the officials? Or is it due to radiation exposure? Or is it for some other causes?  

The Chicago Tribune editorial concludes that thyroid ultrasound screening in Fukushima is causing overdiagnosis and suggests overtreatment might be damaging the Fukushima children, but clearly author(s) did not review the clinical details of the operated cases. 

This is not surprising because clinical and pathological information of the operated cases has not been officially released in English and thus not readily available. Pieces of information have trickled out, mostly in Japanses, as abstracts for presentations at Japanese academic conferences and two reports submitted to the Thyroid Examination Evaluation Subcommittee of the Fukushima Health Management Survey Oversight Committee (see the November 29, 2014 post, the June 23, 2015 post, and the September 10, 2015 post for details).

It is important to understand that clinical and pathological information released by FMU is not comprehensive enough to allow for any meaningful analysis of the surgical cases. However, even with such limited information, it is clear that  surgeries were medically indicated for the vast majority of the cases for reasons such as lymph node and/or distant metastases and close proximity of the tumor to vital structures such as the vocal cord, trachea, or recurrent laryngeal nerve. Pathological analysis of the surgical specimen revealed 39% had mild extrathyroidal extension (cancer cells spreading beyond the covering of the thyroid gland), and 74% had lymph node metastasis. In order to preserve thyroid hormone secretion, only half of the thyroid gland was removed in 94% of the operated cases. (At the press conference of a newly launched “311 Thyroid Cancer Family Group [15],” a physician advisor to the group revealed there were a few cases of recurrence, but this information has been neither released nor confirmed by FMU). 

Furthermore, the interim result of the second round screening shows 40 (80%) of 51 cases suspected or confirmed of thyroid cancer had no ultrasound findings of precancerous tumor in the first round screening—in fact, 25 cases (50%) had no ultrasound findings at all. In other words, for the majority of the cancer cases diagnosed in the second round screening, cancer grew in two to two and a half years since the first round screening.  

Thus the clinical information suggests aggressiveness and fast progression of the thyroid cancer being diagnosed in Fukushima children. (Incidentally, the April 14, 2016 New York Times article [16] reports a type of thyroid cancer, encapsulated follicular variant of papillary thyroid cancer, is reclassified as a benign thyroid tumor [17]. It has been reported that 3 of 87 thyroid cancer cases operated by the end of 2014 were classified as the follicular variant of papillary thyroid cancer [18]. However, there is no sufficient information regarding whether these 3 cases were encapsulated or not).

Two groups of Japanese researchers did calculations to conclude the thyroid cancer occurrence is about 20-60 times the expected rate. Both groups seem to agree this is more than expected from the screening effect—detection of “quiet” and asymptomatic thyroid cancer due to the screening activity—alone.

Tsuda et al., aforementioned in section 1, claim that the excess cases might reflect some screening effect but the radiation effect should also be considered, pointing out the potentially higher exposure doses and the clinical features of the cancer cases.

The study by Tsuda et al. drew a number of criticisms domestically and internationally, mainly for comparing prevalence obtained from screening with incidence of clinically diagnosed cases. Local newspapers in Fukushima Prefecture never covered the release of the Tsuda et al. study. However, a second group of researchers conducted a similar comparison using different methods without such overt criticisms. 

In November 2014, Shoichiro Tsugane, a National Cancer Center epidemiologist and a member of the Fukushima Health Management Survey as well as the Thyroid Examination Evaluation Subcommittee, presented to the Subcommittee a document showing how many cases of thyroid cancer would have been diagnosed in Fukushima Prefecture in 2010, the year before the accident, calculated from the national annual incidence rate [19, 20]. He concluded the observed cancer cases were 61 times the expected and attributed the excess to overdiagnosis. The same estimate was also published in English [21]. In 2015, a related paper was published by Tsugane’s team with updated data, showing the observed rate was about 30 times the expected rate and attributing this increase to overdiagnosis due to screening [22]. Their estimate is included in the Interim Summary by the Fukushima Health Management Survey Oversight Committee [23] as the expression, “several tens of time larger than expected.” 

From published interviews of Tsugane, it is clear he is not considering clinical details of the surgical cases [24] in claiming overdiagnosis which means diagnosis of cancer that does not necessarily need medical intervention. 


Conclusion

When writings such as the March 25, 2016 Chicago Tribune editorial mislead readers on facts of the issue, it is damaging to Fukushima people whose plight is lessened and disregarded. But the core issue is the release of biased information by the authorities, especially in English. This gap in information only adds to the pre-existing language barrier, distorting information transmission.

It is essential for every one of us to be well informed and develop critical thinking in order to counter the one-sided flow of distorted information. The recently established family support group for thyroid cancer patients, “311 Thyroid Cancer Family Group,” will provide the platform for the patients and families to voice their concerns. What is urgently called for is a comprehensive evaluation of data in a transparent and unbiased manner by third-party expert groups, such as the International Society for Environmental Epidemiologists [25].

1. http://fmu-global.jp/?wpdmdl=1222
2. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0083220
3. http://www.nature.com/articles/srep09046
4. http://journals.lww.com/epidem/Fulltext/2016/05000/Thyroid_Cancer_Detection_by_Ultrasound_Among.3.aspx
5. http://journals.lww.com/epidem/Fulltext/2016/05000/The_Authors_Respond.37.aspx
6. https://www.iwanami.co.jp/kagaku/20120913_2.pdf#69
7. https://www.iwanami.co.jp/kagaku/20120913_2.pdf#74
8. http://online.liebertpub.com/doi/abs/10.1089/thy.2014.0198
9. http://www.karger.com/Article/FullText/437263
10. http://iopscience.iop.org/article/10.1088/0952-4746/36/2/E1
11. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1007563/?page=1
12. http://www.rri.kyoto-u.ac.jp/NSRG/reports/kr79/kr79pdf/Malko2.pdf
13. http://www.aec.go.jp/jicst/NC/tyoki/bunka5/siryo5/siryo42.htm
14. http://www.nature.com/nrc/journal/v13/n7/full/nrc3536.html
15. http://www.asahi.com/ajw/articles/AJ201603240025.html
16. http://www.nytimes.com/2016/04/15/health/thyroid-tumor-cancer-reclassification.html?_r=1&referer=
17. http://oncology.jamanetwork.com/article.aspx?articleid=2513250
18. http://fukushimavoice-eng2.blogspot.com/2015/06/2015-update-details-of-fukushima.html
19. https://www.pref.fukushima.lg.jp/uploaded/attachment/91000.pdf
20. http://fukushimavoice-eng2.blogspot.com/2015/08/the-estimated-number-of-prevalent-cases.html
21. http://www.bmj.com/content/346/bmj.f1271/rr
22. https://jjco.oxfordjournals.org/content/early/2016/01/10/jjco.hyv191.full
23. https://www.pref.fukushima.lg.jp/uploaded/attachment/158522.pdf
24. http://fukushimavoice-eng2.blogspot.com/2015/09/surgical-and-pathological-details-of.html
25. http://www.isee-europe.com/blog/open-discussion-on-isees-letter-to-the-authorities-in-japan-concerning-the-paper-by-tsuda-et-al-2015#comments