Fukushima Thyroid Examination Fact Sheet: May/June 2014

Below is a synopsis of the thyroid ultrasound examination, being conducted in Fukushima Prefecture since October 2011. The synopsis is intended to organize and clarify available information regarding thyroid cancer cases discovered in Fukushima residents, who were ages 18 or younger at the time of the March 2011 Fukushima nuclear accident. It also includes some information gathered from various committee meetings, conducted and streamed live online only in Japanese. 

Fukushima Thyroid Examination Fact Sheet: May/June 2014

In October 2011, seven months after the Fukushima Dai-ichi nuclear power plant meltdowns and explosions, Fukushima Prefecture began thyroid ultrasound examination, as part of Fukushima Health Management Survey1 (now called Fukushima Health Survey), in over 360,000 children. These children were younger than 18 at the time of the accident, and most of them did not receive adequate protection of stable iodine tablets for prevention of thyroid cancer. This was intended to be the baseline examination to assess the current condition of their thyroid glands. The thyroid gland is known to be affected, especially in children, by radioactive iodine 131 emitted from a nuclear accident.

The plan was to conduct the preliminary (first-round) thyroid ultrasound examination in all 360,000 plus children, beginning with municipalities with the highest radiation exposure doses. With Fukushima Medical University (FMU) being the sole conductor of the examination initially, as commissioned by Fukushima Prefecture, the first round of the examination was completed in late March 2014, at the end of Fiscal Year 2013. Cumulative results have been released every 2 to 4 months2, as the examination progressed on each year's cohort.

The final results of the first round of thyroid ultrasound examination from October 2011 to March 2014 are not yet known as of May 2014, since the secondary examination has not been completed. However, the results tallied up to March 31, 2014 were released on May 19, 2014, at the 15th Prefectural Oversight Committee Meeting for Fukushima Health Survey3.

Thyroid ultrasound examinations conducted on 295,511 Fukushima children (final results known for 287,056 children as of February 21, 2014) since October 2011, revealed that 136,804 children (47.7%) had an "A2" assessment, with either cysts 20.0 mm or smaller or nodules 5.0 mm or smaller. In addition, 2,069 children (0.7%) had a B assessment, indicating cysts 20.1 mm or larger or nodules 5.1 mm or larger, qualifying them for secondary examinations, including a more detailed ultrasound examination, blood and urine tests checking for thyroid function and iodine excretion, and fine-needle aspiration biopsy if necessary. Of these 2,069 children, 1,754 actually received the secondary examination.

So far, there are 49 papillary thyroid cancer cases, which were the most common form of thyroid cancer found in children after the 1986 Chernobyl accident, and 39 have suspect biopsies, meaning they need surgery to obtain a section of thyroid gland for tissue biopsy. Another cancer case is suspected to be of the poorly-differentiated subtype, with the final tissue diagnosis pending. The total number of confirmed thyroid cancer cases is 50, and the total number of confirmed and suspected cancer cases is 90 (this number is sometimes reported as 89, excluding one case that was confirmed to be benign). 32 were male and 58 were female, with an average age of 14.7 ± 2.7 (age range 6-18) at the time of the accident. The tumor size ranged from 5.1 mm to 40.5 mm. The youngest was a girl who was 6 at the time of the accident.

The incidence, or more accurately, prevalence, is thus 30.1 per 100,000 overall or 16.6 per 100,000 for confirmed cases so far. Although it is not possible at this time to determine if these cancers are radiation-induced or not, drawing on Japanese cancer incidence statistics, 3 or fewer cases of thyroid cancer would be expected in this population per year. (In 2010, normal incidence of thyroid cancer in Japan was 0.1 in 100,000 below age 15 and 1.1 in 100,000 in age 15-194,5). According to the National Cancer Institute, pediatric thyroid cancer incidence in the US, is 0.2 in 100,000 below age 15 and 1.76 per 100,000 in age 15-19 (12.2 in 100,000 in adults6).

So far, the official consensus of the Ministry of the Environment (MOE) of the Japanese government, FMU, and the United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR) appears to be that the finding constitutes a “screening effect,” which means thyroid cancer is being discovered as all children in Fukushima Prefecture are screened7,8. MOE also conducted a study in distant prefectures, supposedly unaffected by radiation exposure, but the study population is not age- and sex-matched to the Fukushima cohort and the two datasets cannot be directly compared9.

It should be noted that about 20% of the 368,651 Fukushima children never underwent the first round of thyroid ultrasound examination for various reasons. In addition, about 15% of the 2,070 children are yet to undergo the required secondary examination, and 10% of the 1,754 who underwent the secondary examination are still awaiting their results.

In the full-scale examination beginning April 2014, those born between April 2, 2011 and April 1, 2012 will be included, some of who were exposed in utero, making the total to be examined 385,000 in a two-year period. Fukushima Prefecture is now offering more facilities to conduct the examination in Fukushima. Agreements have been signed with various medical facilities nationwide to conduct the thyroid examination, so that 17,634 children residing outside Fukushima Prefecture can have an easier access.

Additional information:

Shunichi Yamashita, in charge of the Fukushima Health Survey until March 2013, initially claimed any thyroid cancer discovered during the screening would be latent cancers which would not have been discovered until much later if the screening hadn't been conducted.

At the June 2013 meeting of the Thyroid Examination Assessment Subcommittee, Shinichi Suzuki, an FMU professor currently directing the thyroid examination, admitted that some of the 50 cancer cases had lymph node metastasis or symptoms such as hoarseness which validated thyroidectomy. Suzuki had also maintained these cancers represented latent cancers.

This revelation came when Suzuki was grilled about the possibility of overdiagnosis and overtreatment by one of the subcommittee members, Kenji Shibuya10, a public health specialist at the University of Tokyo Graduate School of Medicine. Shibuya co-authored an article raising the issue of thyroid cancer overdiagnosis and overtreatment, published in Lancet11 in May 2014.

Although Suzuki mentioned the existence of conditions which would justify surgery, he would not release any detailed data such as the actual number of such cases. However, his admittance of lymph node metastasis in some of the cases seems to contradict the initial claim that these cancers were latent cancers which would never have been found.

This is a controversial topic, and we are awaiting a release of some of the data by FMU. By the way, although no longer attending the Prefectural Oversight Committee Meeting for Fukushima Health Survey, Shunichi Yamashita remains as the senior director of thyroid ultrasound examination12.

5 Matsuda A, Matsuda T, Shibata A, Katanoda K, Sobue T, Nishimoto H and The Japan Cancer Surveillance Research Group. Cancer Incidence and Incidence Rates in Japan in 2008: A Study of 25 Population-based Cancer Registries for the Monitoring of Cancer Incidence in Japan (MCIJ) Project. Japanese Journal of Clinical Oncology, 44(4): 388-396, 2013

The July 22 Tokyo Shimbun article, "Running Backwards on Health Support After the Nuclear Accident: Ministry of Environment Expert Meeting"

On July 22, 2014, Tokyo Shimbun published an article titled, "Running Backwards on Health Support After the Nuclear Accident: Ministry of Environment Expert Meeting." The entire article is only available in the paper edition as in the image below, but it has been written out in this blog post.

Below is the complete English translation of this article.

Running Backwards on Health Support After the Nuclear Accident: Ministry of Environment Expert Meeting

The Ministry of the Environment (MOE) Expert Meeting Discussing Health Support After the Fukushima Nuclear Accident is taking an unthinkable twist. At the July 16th meeting, an outside researcher asked for the expansion of health checkups, but the committee chair looked the other way, stating “I don’t want to discuss the issue.” The expansion of health checkup is part of the Act Concerning Support for Children and Disaster Victims, but the committee chair himself voiced an opinion, “We now have different circumstances from when the Act was first approved.” There is no way disaster victims can accept such attitudes. (by T. Sakakibara)

◆ Hesitant on the Expansion of Health Checkups

“Radioactive materials [being disseminated due to the Fukushima nuclear accident] are not thought to remain within borders of Fukushima Prefecture. We need to urgently figure out if there are any cases in non-Fukushima residents. We should not be fixated only on dose assessments.”

It was the Ministry of the Environment Expert Meeting held on July 16th. An invited guest speaker Toshihide Tsuda, an epidemiologist and an Okayama University professor, challenged the current state of the meeting spending time on discussing what the exposure dose was for residents within and out of Fukushima Prefecture.

However, Shigenobu Nagataki, the committee chair and a former chairman of Radiation Effects Research Foundation, pushed aside what Professor Tsuda pointed out, stating, “You are extremely unique.”

Fukushima Prefecture began the Prefectural Resident Health Survey immediately after the accident, including thyroid examination for those who were under age 18 at the time of the accident. However, the central government currently pays for health examination only for Fukushima residents. Therefore, the Expert Meeting is presently discussing whether other areas might need health checkups.

Chairman Nagataki has set a policy to: 1) Assess the exposure dose for residents within and out of Fukushima Prefecture; 2) Analyze health effects based on the dose; and 3) Consider which health support might be necessary. At the last meeting (the seventh session) on June 26th, the rough outline of dose assessment was finally put together.

The outline, based on the dose estimates by an Independent Administrative Institution, National Institute of Radiological Sciences, as well as the behavior questionnaire of residents by Fukushima Prefecture, stated that the internal exposure dose from radioactive iodine that can cause thyroid cancer was “mostly under 50 mSv.” In regards to the external exposure dose, it noted that “The survey finding, ’99.8% was under 5 mSv in Fukushima Prefecture,’ could be reasonably applied to see the overall tendency.”

However, there are large uncertainties in this assessment result.

Only about 1,000 had direct measurements of exposure from radioactive iodine taken, which is 0.3% of residents eligible for thyroid examination by Fukushima Prefecture. Radioactive iodine has a short half-life of 8 days and cannot be measured now. Behavior questionnaires for external dose assessment had a low response rate of only 25.9%.

During the meeting, Professor Tsuda claimed, “When considering a causal relationship between an illness and a cause, data for the cause often tends to be scant. It is a principle of international epidemiological analysis to see it from the side of the illness. Considering the cause first is merely a laboratory method.”

In addition, he continued, “Fixating on dose assessments will delay countermeasures, worsening the damage.” He emphasized that health checkups should be immediately carried out within and out of Fukushima Prefecture, in order to identify cases of thyroid cancer and other illnesses and to analyze whether the number of cases increased after the accident or whether there are regional differences.

Despite inviting Professor Tsuda to the meeting, Chairman Nagataki practically ignored his opinion.

To this response [by Nagataki calling him unique], Professor Tsuda retorted, “My opinions are based on a textbook published by Oxford University Press. Chairman, you are the one that is unique.” However, Chairman Nagataki unilaterally cut off the conversation, stating, “I have no intention of arguing with you. We are going to carry on discussion based on exposure dose.”

◆ Not Meeting the Expectations by Residents

Passive assessments of radiation health effects by the Japanese government predate this meeting.

The Cabinet Office expert meeting, “Working Group (WG) on Risk Management of Low-dose Radiation Exposure,” put together a report in December 2011, concluding, “…increased risk of cancer from low-dose radiation exposures at 100 mSv or less is so small as to be concealed by carcinogenic effects from other factors, making verification of any clear cancer risk from radiation exceedingly challenging.” 

The Cabinet Office WG was also headed by Nagataki. It also included other members of the MOE expert meeting, such as Ostura Niwa, a special professor at Fukushima Medical University, and Keigo Endo, president of Kyoto College of Medical Science.

The expert meeting, at this point of time, is leaning in the direction of “Radiation health effects cannot be proven,” and “As the effects cannot be proven, even health checkups within Fukushima Prefecture are unnecessary,” since the exposure dose within and out of Fukushima Prefecture is expected to be significantly lower than 100 mSv.

In fact, the expert meeting already has some opinions hesitant on expanding health checkups.

The Act Concerning Support for Children and Disaster Victims [English translation here], approved in June 2012, asks for expansion of health checkups as well as reduction of medical expenses, but Chairman Nagataki cast doubt on the need for it at the seventh session, stating “Circumstances are quite different now compared to the time when the act was approved,” and, “As the dose assessment has progressed, we can now make scientific statements in regards to the risk.”

Likewise, during the same session, a member of the expert meeting and a professor at Osaka University, Tomotaka Sobue, explained disadvantages of health checkups using the term, “overdiagnosis.”

This means that since a slow-growing cancer, such as thyroid cancer, has a possibility of never becoming symptomatic in lifetime and causing damages to the body, discovery of cancer during health checkups could cause excessive anxiety and a psychological and physical burden due to surgery.

Another member and the clinic director at International University of Health and Welfare, Gen Suzuki, claimed “An adequate debate needs to be carried out as to whether the best answer is to conduct health checkups as a response to anxiety by residents regarding their health.”

However, requests for expansion of health checkups are swelling from the side of the parties involved, the residents.

On July 13th, there was an event in Metropolitan Tokyo for mothers from within and out of Fukushima Prefecture to talk about life after the nuclear accident.

One of the participants, Kaoru Inagaki (age 42), a member of citizen’s group, Kanto Children Health Survey Support Fund, which conducts thyroid examination in four prefectures including Tochigi, Ibaraki, Chiba and Saitama, said, “When we announce openings for the examination, they are immediately taken up.”

Another participant, Kumi Kanome (age 46), a mother who evacuated with a second-grade daughter to Kanagawa Prefecture from Otama Village, Fukushima Prefecture, appealed, “The nuclear accident increased our worries about children’s illnesses. It is natural for us to want to have them checked out. Regardless of whether living in or outside Fukushima Prefecture, any mother would feel that way.”

Emiko Ito (age 51), director of the event organizer, non-profit organization “National Parents Network to Protect Children from Radiation,” said, “The expert meeting is ignoring the Act Concerning Support for Children and Disaster Victims. That won’t be conducive to resolving residents’ anxiety. It only leads to mistrust.”

Some of the members of the expert meeting have different views. One of them, Hiromi Ishikawa, Executive Director of Japan Medical Association, criticizes, “The present expert meeting does not reflect opinions of the residents. I don’t know why anybody would just one-sidedly tell worried people, ‘It’s okay.’”

From a stand point of “nobody knows the effect of low-dose radiation exposure,” he says, “We need to quickly consider whether there are any illnesses due to radiation and how to deal with them if there are any. Worries can be only resolved when we are prepared that way.”

“Advantages and disadvantages of health checkups are not something that can be uniformly decided by those who are called experts. We need to establish the system for health checkups and let the residents, who are the parties involved, decide.”

Memo from the editing desk:
Mr. Nagataki is running the expert meeting. This fact alone makes it clear how the government has summed up the Fukushima nuclear accident. The predecessor of Radiation Effects Research Foundation was the United States Atomic Bomb Casualty Commission (ABCC), which “investigated the effects of atomic bombs without treatment.” A network originating there was involved in developing the “Myth of Infallible Safety.” Now they are working hard to spread the “Myth of Reassurance.”

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