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Friday, February 24, 2017

Fukushima Thyroid Examination February 2017: 184 Thyroid Cancer Suspected/Confirmed (1 Additional Case)

Highlights:
  • One more case of suspected thyroid cancer was diagnosed by cytology since the last report.
  • No additional surgeries since the last report: the number of confirmed cancer cases remains at 145 (101 in the first round and 44 in the second round)
  • Total number of confirmed/suspected thyroid cancer diagnosed (excluding a single case of benign tumor) is 184 (115 in the first round and 69 in the second round)
  • The second round screening data is still not final (confirmatory examination still ongoing).
  • Thyroid Examination Evaluation Subcommittee will be convened in May or June 2017 to evaluate the results of the second round screening.
On February 20, 2017, less than two months since the last report, the 26th Oversight Committee for Fukushima Health Management Survey convened in Fukushima City, Fukushima Prefecture. Among other information, the Oversight Committee released the latest results (as of December 31, 2016) of the second and third rounds of the Thyroid Ultrasound Examination (TUE). Official English translation of the results will be posted here. The narrative below presents basic facts of TUE and its current results in perspective, including information covered during the committee meeting and the subsequent press conference.

Overview
As of December 31, 2016, there is only 1 more case with cancer or suspicion of cancer from the second round, making a grand total of 184 (185 including the single case of post-surgically confirmed benign nodule) for the first and second round screening results combined. The number of surgically confirmed cancer cases, excluding the aforementioned case of benign nodule, did not change from the previous report (101 from the first round and 44 from the second round), and the remaining 38 (14 from the first round and 24 from the second round) continue to be under observation. 

The second round screening (the first Full-Scale screening) was originally scheduled to be conducted from April 2014 through March 2016, and the primary examination (with the participation rate of 70.9% and the progress rate of 100.0%), is essentially complete. But the confirmatory examination (with the participation rate of 79.5% and the progress rate of 95.0%) is still ongoing. 

The third round screening (the second Full-Scale Screening) began on May 1, 2016 and is scheduled to run through March 2018--the end of Fiscal Year 2018. As of December 31, 2016, 87,217 out of the survey population of 336,623 residents have participated in the ongoing primary examination at the participation rate of 25.9%. The confirmatory examination began on October 1, 2016, with the participation rate of 29.6% so far. 

Full-Scale Screening (first and second)
To be conducted every 2 years until age 20 and every 5 years after age 20, the Full-Scale screening began with the second round screening (the first Full-Scale Screening) in April 2014, including those who were born in the first year after the accident. There are 381,282 eligible individuals born between April 2, 1992 and April 1, 2012. As of December 31, 2016, 270,489 actually participated in the primary examination. 

The participation rate remained the same as 3 months earlier at 70.9% but lower than 81.7% from the first round screening. Results of the primary examination have been finalized in 270,468 participants, and 2,226 (increased by 4 since the last Oversight Committee meeting) turned out to require the confirmatory examination. 

The confirmatory examination is still ongoing for the second round. Of 2,226 requiring the confirmatory examination, 1,770 have participated at the participation rate of 79.5% (increased from the previous 75.8% but still lower than 92.8% from the first round screening). So far 1,681 have received final results including 95 that underwent fine needle aspiration cytology (FNAC) which revealed 69 cases suspicious for cancer. 

Confirmation of thyroid cancer requires pathological examination of the resected thyroid tissue obtained during surgery. There has been no additional surgical case since the last reporting. As of December 31, 2016, 44 underwent surgery and 43 were confirmed to have papillary thyroid cancer. One remaining case was confirmed to have "other thyroid cancer" according to the classification in the seventh revision of Japan's unique thyroid cancer diagnostic guidelines. A specific diagnosis was not revealed, but it has been reported as a differentiated thyroid cancer that is not known to be related to radiation exposure and it is allegedly neither poorly differentiated thyroid cancer nor medullary cancer. 

The third round screening or the second Full-Scale Screening has covered 87,217 or 25.9% of the survey population of 336,623. The primary examination results have been finalized in 71,083 or 81.5% of the participants, revealing 483 to require the confirmatory examination. Results of the confirmatory examination have been finalized in 64 of 143 (29.6%) that have been examined. FNAC was conducted in one person with a negative result: No cancer case has been diagnosed from the third round as of now. 

Confusing issues
Conducted every 2 years up to age 20, the TUE transitions at age 25 to milestone screenings to be conducted every 5 years. Some residents are beginning to participate in the age 25 milestone screening, and if they have never participated in the TUE, their milestone screening results will be added to the second round screening results. Thus the number of the second round screening participants is expected to increase even though the screening period technically ended in March 2016. 

However, the third round screening survey population excludes the age 25 milestone screening participants: their results will be tallied up separately.

Also in some cases, confirmatory examinations from the second and third rounds might be simultaneously ongoing, or there could be significant delays in conducting confirmatory examinations due to logistical issues such as the lack of manpower. A two-year screening period originally designed for subsequent rounds of the Full-Scale Screening is essentially spread over a longer time period, overlapping with the next round of screening. A precise interpretation of results from each round of screening might be nearly impossible.

A newly diagnosed case in the second round
In the second round, only 1 case was newly diagnosed by FNAC with suspicion of cancer. It is a female from Koriyama-City who was 17 years old at the time of the March 2011 disaster. Her first round screening result was A1.

Prior diagnostic status of the cases newly diagnosed with cancer in the second round
Of 69 total cases suspected or confirmed with cancer in the second round, 32 were A1, 31 were A2, and 5 were B in the first round. One remaining case never underwent the first round screening (no information such as age, sex or place or residence, is available regarding this case).

Thirty-two cases that were A1 in the first round, by definition, had no ultrasound findings of cysts or nodules, whereas 7 of 31 cases that were previously diagnosed as A2 had nodules with the remaining 24 being cysts. All 5 cases that were previously diagnosed as B were nodules, and at least 2 of them had undergone the confirmatory examination in the first round. 

This means 56 (32 "A1" and 24 "A2 cysts")of 69 cases had no nodules detected by ultrasound in the first round which could have developed into cancer. This is 81% of the second round cases suspected or confirmed with cancer. It has been speculated by some that these 56 cases were new onset since the first round, suggesting the cancer began to form in 2 to 3 years after the first round screening, conflicting with the common notion that thyroid cancer in general is slow growing. 

Akira Ohtsuru, the head of the TUE, explained that even though some of the small nodules are very easy to detect by ultrasound, exceptions arise when 1) the border of the lesion is ambiguous, 2) the density of the lesion is so low that it blends into the normal tissue, or 3) the lesion resembles the normal tissue. Thus, it is not because the nodules newly formed since the first round screening, but because the nodules were simply not detected even though they were there, that cases which previously had no nodules are now being diagnosed with cancer. Ohtsuru said that when such previously undetected nodules become relatively large enough to become detectable by ultrasound, they might look as if they suddenly appeared. Ohtsuru added that nodules that have already been detected by ultrasound do not to appear to grow very rapidly in general.

This is a better, more legitimate explanation than the previous ones he offered that stated the nodules were present in the first round albeit invisible. However, 56 out of 69 cases seem like a lot to be explained by this.

An issue of the female to male ratio
The female to male ratio of cancer cases warrants a special attention. For thyroid cancer, the female to male ratio is nearly 1:1 in the very young, but it is known to increase with age and decrease with radiation exposure. (See below Slide 2 in this post for more information). In the second round, the female to male ratio has been ranging from 1.19:1 to 1.44:1 overall, but the FY2015 municipalities have consistently shown a higher number of males than females with the most recent female to male ratio of 0.7:1.

What Ohtsuru said about the the female to male ratio boils down to the following: 
The female to male ratio for thyroid cancer is influenced by the reason for diagnosis and the age. When the confirmatory examination of the second round screening is completed, the data will be analyzed by adjusting for age and participation rates by sex. The female to male ratio in Japan's cancer registry data, including all ages, is around 3:1, but it used to be bigger at 4:1 or 6:1 in the 1980's and earlier. In Fukushima, the TUE was conducted in asymptomatic youth around puberty--a different condition than the cancer registry. Yet even in the cancer registry, the female to male ratio tends to be close to 1:1 up to the puberty. Autopsy data of occult thyroid cancer in individuals who died of causes other than thyroid cancer show the female to male ratio of 1:1 or smaller (more males) in adults. This fact indicates that thyroid cancer screening would yield the female to male ratio close to 1:1 even in adults. Thus, it is scientifically expected that thyroid cancer screening in general leads to a smaller female to male ratio.
He is claiming that thyroid cancer diagnosed by cancer screening before becoming symptomatic--as opposed to symptomatic thyroid cancer diagnosed clinically--is expected to show the female to male ratio near 1:1 or smaller, i.e., as many males are diagnosed as females, or more males are diagnosed than females. 

To say the least, calling extrapolation from autopsy data to screening "scientific" seems a bit of a stretch. Furthermore, Ohtsuru's claim does not add up scientifically. South Korea, where active screening increased the incidence of thyroid cancer, did not observe a smaller female to male ratio as shown in the table of thyroid cancer incidence by sex and age group compiled from Ahn et al. (2016). It is obvious the female incidence is much higher than the male incidence without actually calculating the ratio.

Thyroid cancer incidence by sex and age group per 100,000 
in the 16 administrative regions in Korea
 Compiled from Supplementary Tables 2 & 3 in Ahn et al. (2016) Thyroid Cancer Screening in South Korea Increases Detection of Papillary Cancers with No Impact on Other Subtypes or Thyroid Cancer Mortality (link)

Furthermore, Ohtsuru's claim that the female to male ratio tends to be close to 1:1 up to the puberty in the cancer registry is not corroborated by the actual data. The table below was compiled from the National estimates of cancer incidence based on cancer registries. The number of thyroid cancer cases for each sex was listed side-by-side for each year and age group. Then a total from 2000 to 2012 was tallied for each sex and age group to obtain the female to male ratio, because the number of cases varies from year to year. Even without knowing exactly which age range Ohtsuru meant by "up to the puberty," it is clear that the female to male ratio is not at all close to 1:1.


The number of thyroid cancer cases by sex and age group from 2000 to 2012
Compiled from the National estimates of cancer incidence based on cancer registries in Japan (link)

According to this study, the female to male ratio peaks at puberty and declines with age, as excerpted below:
The increased F:M ratio in thyroid cancer incidence does not remain static with age. Female predominance peaks at puberty. [...] This pattern occurs as the thyroid cancer incidence begins to increase at an earlier age in females than in males, leading to a rise in the F:M ratio. The ratio starts to decline as the male incidence rate begins to increase and, concurrently, the rate of increase in female incidence rate slows down. The steady decrease in F:M ratio with age continues, and the peak male rate does not occur until between 65 and 69 years of age, compared with the earlier peak female rate between 45 and 49 years of age, just before the mean age of menopause at 50 years.

An issue of the participation rate
The primary examination participation rate of 70.9% in the second round screening is lower than 81.7% in the first round. Most notable is the participation rate of the oldest age group: 52.7% for ages 16-18 (age at exposure) in the first round plummeted to 25.7% for ages 18-22 (age at examination) in the second round. It is 6.6% for ages 18-24 (age at examination) for the ongoing third round so far.

Younger age groups in school have maintained pretty high participation rates thanks to the school-based screening. The older age group often leave the prefecture for college or jobs, and it becomes increasingly difficult to get them to participate, especially with their interests fading in their busy lives.

The status of the new third-party committee
The "international, third-party, neutral, scientific, up-to-date and evidence-based" expert committee proposed by Chairman Hokuto Hoshi at the last committee meeting is being discussed at the prefectural level in consultation with the central government. The prefectural official admitted that the plan was to establish an independent entity that will offer, from a neutral standpoint, latest knowledge of thyroid cancer needed by the Oversight Committee.

A committee member Tamami Umeda from the Ministry of Health, Labour and Welfare elaborated on her vision of the third-party committee as an entity to review and organize the latest clinical and epidemiological knowledge and studies. It would be separate from the Thyroid Examination Evaluation Subcommittee that is intended to evaluate and analyze the status of the TUE, including the evaluation of radiation effects. (Note: In reality, the Thyroid Examination Evaluation Subcommittee has been far from being effective in analyzing the TUE data due to lack of information released by Fukushima Medical University on the premise of protecting personal clinical data).

Explaining that international organizations frequently separate a scientific review process from discussions relating to policy making in order to maintain neutrality, Umeda said she thought a similar process might be useful for the Fukushima Health Management Survey. This comment drew questions from committee members as well as the press about the status of the Oversight Committee itself: Is it a policy-making body? Is it not scientific enough?

It would make more sense to invite experts to join the Thyroid Examination Evaluation Subcommittee to incorporate knowledge gained from the latest research on thyroid cancer. Why it has to be an "international" committee is unclear other than to say that it was recommended by the Organizing Committee of 5th International Expert Symposium in Fukushima on Radiation and Health, including Shunichi Yamashita. A former chair to the Oversight Committee, Yamashita resigned from the position in March 2013 amid controversies surrounding "secret meetings." Although no longer involved with the Oversight Committee, he has maintained ties with the Survey as Founding Senior Director of the Radiation Medical Science Center for the Fukushima Health Management Survey, the Office of International Cooperation for the Survey.

*****

Below is the summary of the basic information from each round of screening.

First Round Screening (October 2011 - April 2015)
(This is the final results as of March 31, 2016. It is unchanged from the September 2016 report).

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 Screening (April 2014 - March 2016) (see report here)

Total number targeted: 381,282
Number of participants in primary examination: 270,489
Number with confirmed results: 270,468
  • A1   108,688 (40.2%) (no nodules or cysts found)
  • A2   159,554 (59.0%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
  • B        2,226   (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 of residents requiring confirmatory (secondary) examination: 2,226
Number of participants in confirmatory examination: 1,770
Number with confirmed results: 1,681
Number of FNAB: 195
Number of cases with malignancy or suspicion of malignancy: 69
Number with confirmed tissue diagnosis after surgery: 44
  • 43 papillary thyroid cancer
  • 1 "other thyroid cancer"
Third Round Screening (May 2016 - March 2018) (see report here)

Total number targeted: 336,623
Number of participants in primary examination: 87,217
Number with confirmed results: 71,983
  • A1   25,182 (35.4%) (no nodules or cysts found)
  • A2   45,418 (63.9%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
  • B          483  (0.7%) (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 of residents requiring confirmatory (secondary) examination: 483
Number of participants in confirmatory examination: 143
Number with confirmed results: 64
Number of FNAB: 1
Number of cases with malignancy or suspicion of malignancy: 0
Number with confirmed tissue diagnosis after surgery: 0


Second Round Screening


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



Table 6. Cytology results for FY 2014-2015 
(including information from Appendix 6: Surgical cases of suspicious or malignant cases) 
(Data as of December 31, 2016)


Friday, January 6, 2017

Fukushima Thyroid Examination December 2016: 145 Thyroid Cancer Cases Confirmed (101 in the First Round and 44 in the Second Round)

145 Thyroid cancer cases confirmed in Fukushima as of September 30, 2016--101 in the first round and 44 in the second round (Total of 183 cases including suspected cancer cases--115 in the first round and 68 in the second round).

On December 27, 2016, the 25th Oversight Committee for Fukushima Health Management Survey convened in Fukushima City, Fukushima Prefecture. Among other information, the Oversight Committee released the latest results (as of September 30, 2016) of the second and third rounds of the Thyroid Ultrasound Examination (TUE). Official English translation of the results is posted here. The narrative below presents basic facts from the new data in perspective, including information covered during the committee meeting and the subsequent press conference.

Overview
As of September 30, 2016, there are 9 more cases with cancer or suspicion of cancer from the second round, making a grand total of 183 (184 including the single case of post-surgically confirmed benign nodule) for the first and second round results combined. The number of surgically confirmed cancer cases, excluding the aforementioned case of benign nodule, increased by 10 to 145 (101 from the first round and 44 from the second round), and the remaining 38 (14 from the first round and 24 from the second round) await surgical confirmation. 

Although the final reporting of the second round screening results was widely anticipated at this Oversight Committee meeting, it was revealed that the confirmatory examination was still ongoing and the results were incomplete. 

Since the last results were released, 10 additional cases from the second round have been operated on. All 10 cases were confirmed as papillary thyroid cancer during the post-surgical pathological examination of the resected thyroid gland tissue. 

The second round screening (the first Full-Scale screening) was originally scheduled to be conducted from April 2014 through March 2016, and the primary examination (with the participation rate of 70.9% and the progress rate of 100.0%), is essentially complete. But the confirmatory examination (with the participation rate of 75.8% and the progress rate of 92.2%) is still ongoing apparently due to a schedule backlog in local hospitals in cities far from Fukushima Medical University, such as Iwaki City. 

Conducted every 2 years up to age 20, the TUE transitions to milestone screenings to be conducted every 5 years beginning at age 25. Some residents are beginning to participate in the milestone screening at age 25, and if they have never participated in TUE, the results will be added to the second round screening results. Thus the number of the second round screening participants is expected to increase even though the screening period technically ended in March 2016.

Meanwhile, the third round screening (the second Full-Scale Screening) which began on May 1, 2016, is scheduled to run through March 2018--the end of Fiscal Year 2018. As of September 30, 2016, 49,387 have participated in the primary examination out of the survey population of 336,609 residents, at the participation rate of 14.7%. So far 211 have been determined to require the confirmatory examination. Results of the confirmatory examination were not available as it only began on October 1, 2016 and the TUE results released at this Oversight Committee meeting covers data up to September 2016.

In some cases, confirmatory examinations from the second and third rounds might be simultaneously ongoing, or there could be significant delays in conducting confirmatory examinations due to logistical issues such as the lack of manpower. A two-year screening period originally designed for subsequent rounds of the Full-Scale Screening is essentially spread over a longer time period, overlapping with the next round of screening. A precise interpretation of results from each round of screening might be nearly impossible.

Full-Scale Screening (first and second)
To be conducted every 2 years until age 20 and every 5 years after age 20, the Full-Scale screening began with the second round screening (first Full-Scale Screening) in April 2014, including those who were born in the first year after the accident. There are 381,282 eligible individuals born between April 2, 1992 and April 1, 2012. As of September 30, 2016, the participation rate remained the same as 3 months earlier at 70.9% but lower than 81.7% at the first round screening, with 270,454 actually participating in the primary examination. Results of the primary examination have been finalized in 270,431, and 2,222 (increased by 5 since the last Oversight Committee meeting) turned out to require the confirmatory examination. 

The confirmatory examination is still ongoing for the second round. Of 2,222 requiring the confirmatory examination, 1,685 have participated at the participation rate of 75.8% (increased from the previous 66.6% but still lower than 92.8% from the first round screening), and 1,553 have received final results including 189 that underwent fine-needle aspiration cytology (FNAC). FNAC revealed 68 cases suspicious for cancer. Confirmation of thyroid cancer requires pathological examination of the resected thyroid tissue obtained during surgery. As of September 30, 2016, 44 underwent surgery and 43 were confirmed to have papillary thyroid cancer. One remaining case was confirmed to have "other thyroid cancer" according to the classification in the seventh revision of Japan's unique thyroid cancer diagnostic guidelines. A specific diagnosis was not revealed, but Akira Ohtsuru, in charge of the thyroid screening, confirmed that it was neither poorly differentiated thyroid cancer nor medullary cancer. He has previously mentioned it was a differentiated thyroid cancer that is not known to be related to radiation exposure.

The third round screening or the second Full-Scale Screening has covered 49,387 or 14.7% of the survey population of 336,609. The primary examination results have been finalized in 30,253 or 61.3% of the participants, and 211 would require the confirmatory examination. No results from the confirmatory examination were available because it began as of October 1, 2016.

Newly diagnosed cases in the second round
In the second round, 9 cases were newly diagnosed by FNAC with lesions suspicious of cancer. They were 3 females (ages at exposure: 11, 14 and 15) and 6 males (ages at exposure: 7,10, 11, 12, 12 and 16). Their places of residence at exposure (with the number of individuals in parentheses) include FY 2015 target municipalities of Fukushima City (2) and Shirakawa City (1) and FY 2016 target municipalities of Iwaki City (2), Tanakura Town (1) and Kitakata City (3).

The youngest individual newly diagnosed with suspected cancer was age 7 at the time of the accident. The lack of surge in cases in younger patients aged 0-5 at exposure in the first 4-5 years since the Fukushima nuclear accident is regarded by Fukushima Medical University as one of the reasons denying Fukushima thyroid cancer cases being radiation-induced. However, it was after the first 4 years since the Chernobyl accident that thyroid cancer cases in those aged 0-5 at exposure dramatically increased. This underscores the importance of continuing screening to follow the trend in this age group. No determination could be logically made regarding radiation effects based on the lack of patients who were ages 0-5 at the time of the Fukushima accident. (See this for more information).

Prior diagnostic status of the cases newly diagnosed in the second round
Of 68 total cases suspected or confirmed with cancer in the second round, 31 were A1, 31 were A2, and 5 were B in the first round. One remaining case never underwent the first round screening (no information such as age, sex or place or residence, is available regarding this case).

Thirty-one cases that were A1 in the first round by definition had no ultrasound findings of cysts or nodules, whereas 7 of 31 cases that were previously diagnosed as A2 had nodules with the remaining 24 being cysts. All 5 cases that were previously diagnosed as B were nodules, and at least 2 of them had undergone the confirmatory examination in the first round. 

This means 55 of 68 cases or 81% of the second round cases suspected or confirmed with cancer had no lesions detectable by ultrasound in the first round. It has been speculated by some that these 55 cases were new onset since the first round, suggesting the cancer began to form in 2 to 3 years after the first round screening. This would seem to conflict with the common notion that thyroid cancer in general is slow growing. 

Ohtsuru emphasized that there were no missed diagnosis in the first round. Rather these 55 cases might comprise newly detected lesions that were simply undetectable by ultrasound in the first round. He firmly denied these were newly formed lesions. He also stated it wasn't clear if they were previously invisible, which is the expression he used in earlier meetings. 

Other physicians in the committee, Akihito Horikawa (Futaba County Medical Association president) and Kazuo Shimizu (a thyroid surgeon), concurred with the idea that some lesions might have been simply undetectable even with the use of highly sensitive equipments, although Shimizu did not seem to completely disregard the possibility of new onset lesions. It seemed that the expression of "missed diagnosis" was avoided in honor of considerable efforts made by those actually conducting the ultrasound screening. It is possible some of the ultrasound images are overread at the diagnostic subcommittee with undisclosed members discussing some of the cases in closed meetings, but so far no concrete evidence has been given to confirm such activities.

An issue of the female to male ratio
The female to male ratio of cancer cases warrants a special attention. For thyroid cancer, the female to male ratio is nearly 1:1 in the very young, but it is known to increase with age and decrease with radiation exposure. In the second round, the female to male ratio has been decreasing with successive results. It was 1.36:1 when the results were released in September 2016, and now it is 1.19:1. 

Towards the end of the press conference, Mako Oshidori sharply asked why there has been no evaluation regarding the female to male ratio in the Fukushima thyroid cancer cases. (For the transcript of her question in Japanese, see here). She pointed out that Kazuo Shimizu, a committee member and thyroid surgeon, has asked questions regarding the female to male ratio issue multiple times in the past three and a half years. In fact, Ohtsuru responded to an earlier question by Shimizu during this meeting that the female to male ratio issue is yet to be evaluated by Fukushima Medical University and that the committee meeting was simply a place where results were presented. 

Oshidori chastised Fukushima Medical University for not even trying to compare results with existing outside data and conduct any analysis in all these years. In response, Ohtsuru acknowledged that the female to male ratio is smaller than what is clinically expected but explained they were not sure what is causing it. Oshidori stated there was no scientific paper that showed a decrease in the female to male ratio due to the screening activity. Rather, scientific evidence shows screening activities generally increase the female to male ratio due to more females being diagnosed with thyroid cancer. Ohtsuru replied that it is true that screening activities increased the female to male ratio in adults but it was unclear if the similar trend is expected in children. Furthermore, differences in a screening frequency and screening equipments should be taken into consideration. Oshidori acknowledged there was much to be considered and pressed for the Thyroid Examination Evaluation Subcommittee to be reconvened.

A new third-party committee proposed
At the end of the Oversight Committee meeting, an issue was raised by Chairman Hokuto Hoshi relating to the recommendations received by the Fukushima governor from the 5th International Expert Symposium in Fukushima on Radiation and Health: “Chernobyl+30, Fukushima+5 - Lessons and Solutions for Fukushima’s Thyroid Question." (See this post for more information on the symposium). Hiroyuki Kobayashi, a Fukushima prefectural government official in charge of the Fukushima Health Management Survey, reported that the governor received the recommendations on December 9, 2016. Kobayashi stated that the prefectural government has received opinions and suggestions from various entities and the recommendations by the 5th International Expert Symposium were placed in the same category (as if to explain the recommendations did not have any special status). Kobayashi then asked the committee to discuss the recommendations.

In his monologue, Chairman Hoshi went on to propose an establishment of an "international, third-party, neutral, scientific, up-to-date and evidence-based" expert committee that would discuss issues surrounding the TUE and present information in a manner that would aid the "understanding by Fukushima residents." This proposal appeared to be taken from the item number 4 of the recommendations "to convene the expert working groups on 'Nuclear Disasters and Health Monitoring,' especially focusing on thyroid problems, could provide professional recommendations to the current TUE in Fukushima in the future."

Chairman Hoshi proceeded to have some of the committee members explain how third-party evaluation committees function at the Radiation Effect Research Foundation (RERF) and the National Institute of Radiological Sciences (NIRS). This clearly came as a surprise to those who were asked to make presentations on the spot, creating a slightly uncomfortable atmosphere. 

Multiple questions and opinions ensued during the press conference doubting the necessity and validity of such a new third-party committee when the Oversight Committee's own Thyroid Examination Evaluation Subcommittee, which last met in March 2015 and issued a mid-term report on the first round screening, has not even been reconvened to consider the second round screening results. (At the last Oversight Committee meeting held on September 14, 2016, the FMU officials said the second round screening data would be analyzed when all the second round data is in, and the Oversight Committee itself seemed to be waiting for the completion of the second round rather than holding the subcommittee meetings concurrently).

Regarding the future status of the TUE 
The recommendations by The 5th International Symposium include clauses such as:

"(...) thyroid screening of people who do not have symptoms of possible thyroid disease has the potential to do more harm than good to the population, and should only be carried out, when clear benefits to the population can be defined."

"Participation in the health surveys and the thyroid screening program should be voluntary."

It should be noted that the recommendations did not consider opinions by Chernobyl researchers such as Yuri Demidchik from Belarus, Tetiana Bogdanova from Ukraine and Pavel Rumiantsev from Russia, whose presentations at the symposium made clear that thyroid ultrasound screening is beneficial, since their names are not included in the list of invited experts who were consulted.

For record, participation in the health surveys and the TUE has always been voluntary yet strongly encouraged. On September 13, 2016, the Fukushima prefectural assembly unanimously voted to support a bill introduced to maintain the current status of TUE rather than reducing its scale. (See Bill #63 in this PDF). However, a concern has been raised by an FMU physician, Sanae Midorikawa, that an individual's desire for non-participation should be honored in view of the fact thyroid cancer screening is unlikely to reduce mortality--the purpose of most cancer screenings. Midorikawa worries more about the mental effects of cancer diagnosis. (See this post for the background information and an official translation of a newspaper article. Official translation is found here).

However, all this talk about making it easy for residents to opt out of the health surveys and the TUE is based on the assumptions that radiation effects are unlikely in Fukushima due to much smaller radiation exposure doses than Chernobyl and that the age distribution of those diagnosed with thyroid cancer--including only 1 case exposed at age 5--differs from Chernobyl where many cases were diagnosed in those who were aged 5 or younger at exposure.

Moreover, the clinical information of cancer cases is not taken into consideration. In fact, clinical data is not willingly released citing the privacy protection of the patients. Shinichi Suzuki's presentation at the 5th International Symposium came as a surprise (see this post for details). Concerning clinical features include:

  • a high rate of lymph node metastases
  • microcarcinoma (diameter ≤ 10 mm) requiring surgical intervention for various reasons--cancer cells moving outside the thyroid capsule or invading surrounding structures such as the trachea or the recurrent laryngeal nerve
  • a low female to male ratio

It is precisely these clinical features that should be discussed at the Thyroid Examination Evaluation Subcommittee, given the fact there are many unknowns about thyroid cancer in children and young adults diagnosed by screening before clinical symptoms appear.

Thyroid cancer cases outside Fukushima Prefecture
Furthermore, an independent group, "311 Fund for Children with Thyroid Cancer ," established on the principles of the Nuclear Accident Child Victims’ Support Law which was enacted but never actually carried out by the Japanese government, released some information at a December 27, 2016 press conference, shortly before the 25th Oversight Committee meeting. The 311 Fund for Children with Thyroid Cancer collects donations nationwide and offers 100,000 yen (about $864 at today's exchange rate) to an individual aged 25 or younger diagnosed with thyroid cancer and residing in 11 prefectures that received a significant amount of radioactive iodine after the Fukushima nuclear accident. The financial support is intended to help alleviate the financial strain experienced by the patients and their families in undergoing cancer treatment. This should have been covered by the Nuclear Accident Child Victims' Support Law which was intended to provide health care and financial support for relocation in areas exposed to radiation. Although the Nuclear Accident Child Victims' Support Law covers conditions which are potentially related to radiation exposure, distribution of the financial support by the 311 Fund for Children with Thyroid Cancer does not prove or certify the particular thyroid cancer case is radiation-induced. 

The 311 Fund for Children with Thyroid Cancer approved 35 of 36 application received so far (one rejected application was for a benign thyroid tumor that required surgery). Thirty-five approved cases included 26 cases from Fukushima and 9 cases outside Fukushima: 1 case each from Miyagi, Gunma, Chiba, Saitama, Nagano and Niigata, and 3 cases from Kanagawa. There were 14 males and 21 females, with the current age ranging from 10 to 25 years. In the 9 cases outside Fukushima, 87% had lymph node metastasis and 90% had total thyroidectomy. Three of 9, all from different prefectures, had lung metastases and undergoing a radioactive iodine ablation treatment, which qualifies them for an additional 100,000 yen.

Moreover, it was revealed that 2 of 26 cases from Fukushima developed symptoms after the prefecture-run TUE cleared them of and sought further medical care on their own, disqualifying them from receiving a financial support from Fukushima Prefecture.

Conclusion
It seems important to continue the TUE and even extend it outside Fukushima Prefecture, but it is also critical that the Thyroid Examination Evaluation Subcommittee be reconvened to review the data.

*****
Below is the summary of the basic information from each round of screening.

First Round Screening (October 2011 - April 2015)
(This is the final results as of March 31, 2016. It is unchanged from the previous report).

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 Screening (April 2014 - March 2016) (see report here)

Total number targeted: 381,282
Number of participants in primary examination: 270,454
Number with confirmed results: 270,431
  • A1   108,675 (40.2%) (no nodules or cysts found)
  • A2   159,534 (59.0%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
  • B        2,222   (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 of residents requiring confirmatory (secondary) examination: 2,222
Number of participants in confirmatory examination: 1,658
Number with confirmed results: 1,553
Number of FNAB: 189
Number of cases with malignancy or suspicion of malignancy: 68
Number with confirmed tissue diagnosis after surgery: 44

  • 43 papillary thyroid cancer
  • 1 "other thyroid cancer"

Third Round Screening (May 2016 - March 2018) (see report here)

Total number targeted: 336,609
Number of participants in primary examination: 49,387
Number with confirmed results: 30,253
  • A1   10,984 (36.3%) (no nodules or cysts found)
  • A2   19,058 (63.0%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
  • B          211  (0.7%) (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 of residents requiring confirmatory (secondary) examination: 211
Number of participants in confirmatory examination: 0
Number with confirmed results: 0
Number of FNAB: 0
Number of cases with malignancy or suspicion of malignancy: 0
Number with confirmed tissue diagnosis after surgery: 0


Second Round Screening


Table 6. Cytology results (including information from Appendix 6: Number of surgeries among cases with malignancy or suspicion of malignancy) as of September 30, 2016