The Fukushima Daiichi nuclear power plant accident caused a surge in the number of thyroid cancers? The possibility of "overdiagnosis"

Considering that the EU will publish the "Taxonomy Regulation" in the near future, whether nuclear energy will be included in the sustainable investment classification has become the focus of attention from all walks of life.

In this regard, five former Japanese prime ministers (Junichiro Koizumi, Yuki Hosokawa, Naoto Kan, Yukio Hatoyama, and Tomichi Murayama) sent a letter to the European Commission on the 27th of last month, taking the Fukushima Daiichi nuclear power plant accident as an example, hoping that the European Union will enforce the law. The Commission does not list nuclear energy as a sustainable investment project.

Although the European Union's bill announced on the 2nd of this month has officially listed nuclear energy as a sustainable investment project (for details, please refer to the post on energy on Friends.com ), but the Japanese version of the letters of the five former prime ministers was referred to as "original". The anti-nuclear group of （原発ゼロ・自然エネルギー推進連盟） ” was published on the website , and the content of the letter caused controversy.

" Many children suffer from thyroid cancer "?

The five former Japanese prime ministers mentioned in the letter that they have witnessed an unprecedented tragedy and (radiation) pollution in Fukushima in the past 10 years. Hundreds of thousands of people have left their hometowns, and vast farmland and pastures have been polluted by (radiation). Polluted water that is difficult to store （＊編註：應該是「處理水」） is still increasing, and many children suffer from thyroid cancer and lose a lot of national wealth. I hope everyone in Europe will not repeat the same thing.

The most critical issue in the above passage is the phrase " many children suffer from thyroid cancer ".

Indeed, after the Fukushima Daiichi nuclear power plant accident, Fukushima Prefecture had long-term tracking and testing for signs of thyroid cancer for minors who were under the age of 18 at the time in 2011. To date, 266 children have been diagnosed with thyroid cancer, or are suspected to have thyroid cancer.

However, the United Nations and the Fukushima prefecture's expert committee have already stated that it cannot be concluded that thyroid cancer is related to the radiation leaked from the Fukushima Daiichi nuclear power plant accident. That's because the 266 children who were diagnosed with (suspected) thyroid cancer were likely "overdiagnosed" to screen out more potential patients than usual. Moreover, the comprehensive general screening of juvenile thyroid cancer implemented in Fukushima Prefecture has also raised medical and research ethics issues.

Regarding the difference between "treated water" and "polluted water", please refer to the old article " The polluted treated water of the Fukushima Daiichi nuclear power plant can only be discharged to the sea? Understand what tritium-containing treated water is at once” and “Relevant arrangements after the tritium-containing treated water of Fukushima Daiichi Nuclear Power Plant is determined to be discharged into the sea”

Comprehensive screening after the accident at the Fukushima Daiichi nuclear power plant

When it comes to juvenile thyroid health checks in Fukushima Prefecture, it has a lot to do with the Chernobyl accident.

After the Chernobyl accident, it was discovered that many children had abnormal thyroid function, and then they noticed that the radioactive iodine isotope leaked from the nuclear power plant accident could easily cause thyroid disease if inhaled, and the impact on minors was particularly obvious.

As a result, radioactive iodine isotopes were also released during the Fukushima Daiichi nuclear power plant accident. People from all walks of life were worried that it would affect the thyroid health of local children, so they followed the practice of the former Soviet Union and regularly targeted minors in Fukushima Prefecture after the accident. Perform thyroid ultrasound screening.

However, compared with the amount of radioactive iodine isotopes released during the Chernobyl accident, the amount of radiation leaked from the Fukushima Daiichi nuclear power plant accident was much lower. Not too many cases of thyroid cancer are found.

Thyroid cancer detected early does not necessarily require treatment

Now because of the epidemic, everyone should already have some idea of the negative impact that "large-scale general screening" may cause.

Originally, the screening test for thyroid cancer was to find out what kind of symptoms the client might have. However, when comprehensive screening is implemented, no matter whether there are symptoms or not, they will be arrested for screening, and it is possible to screen out patients who "have not actually developed the disease or have any symptoms, but have been detected with abnormal thyroid function".

Everyone often hears "early detection, early treatment", but the disease of abnormal metathyroid function occurs when you are young. Even if you don't get special treatment, you may get better when you grow up, and it will not have much impact on the person's life. If you use the metaphor of COVID-19, an asymptomatic infection or a mild patient will actually get better as long as he rests for a period of time; if he is not a contact of a confirmed person, he will usually be screened and found to be a confirmed person. Because the person has symptoms and needs treatment, he will go to the screening.

In the same way, in the past, symptoms were already present and the client needed treatment before going to the hospital for screening and finding that it was thyroid cancer. If the thyroid function is abnormal, but there are no symptoms, it will not affect the life of the client, he will not go to the hospital for screening at all, and then he finds that he has a thyroid problem.

This is called "over-diagnosis (over-diagnosis)": after doing more precise tests that were not needed before, it is found that the person's physical condition is a little abnormal, but this abnormality may not affect the person's health or life.

Thyroid cancer "overdiagnosis" problem

What's the problem with "overdiagnosis" of thyroid cancer?

1. If a child with abnormal thyroid function is discovered early without any symptoms, even if the doctor says, "This can be observed again, no treatment is needed", the person or family members may be very worried about "small disease and serious disease". As a result, unnecessary surgery was performed for the abnormal thyroid function that might have improved on its own.
2. It was clearly intended to appease the uneasy mood of the people of Fukushima Prefecture, but as a result, "overdiagnosis" has caused more people to worry about thyroid dysfunction that does not require special treatment. Did this appease the uneasy mood of the people?
3. Because Fukushima prefecture implements comprehensive screening on campus, everyone in the class will know who is diagnosed and who is fine. It is very likely that patients will be labelled indiscriminately, suffer unnecessary social stigma, and become a human rights issue.

Then there are the issues of medicine and research ethics.

Since Fukushima prefecture conducts comprehensive screening for students below high school students, was there a complete explanation to the students and their parents beforehand? Is there really no right to refuse screening? Actually a big problem.

Sanae Midorikawa, a physician who was in charge of thyroid testing in Fukushima Prefecture and has now left Fukushima Medical University, pointed out that although Fukushima Medical University was entrusted by Fukushima Prefecture to assist in the screening, there were always voices questioning within Fukushima Medical University at that time, and there was a problem with doing so. , this may become a situation of "over-diagnosis", and there are doubts about mandatory screening of students when doing tests in schools. However, from the standpoint of protecting the health of the people of Fukushima Prefecture, Fukushima Medical University still took on this task.

However, 116 schoolchildren (suspected) had thyroid function problems in the first screening, and 71 were found in the second screening. South Korea first published a paper in 2014 raising the issue of "overdiagnosis" of thyroid screening , and more and more external voices later questioned the issue of thyroid screening in Fukushima Prefecture. Therefore, Fukushima Prefecture once suspended the implementation, but maintained the original practice to continue screening, because the research process was not suitable for changing the inspection method in the middle.

This is also a point that Fukushima prefecture's implementation of thyroid screening for minors has been questioned: Is this screening for the benefit of the prefecture? Or for research? If you are doing research, you will go back to what I said earlier. Have you explained it clearly to the parties before the test? Is there any right to refuse testing?

Thyroid cancer in Fukushima Prefecture and radiation related?

At this stage, the results of large-scale screening tests published by the Fukushima Prefecture Health Survey and Review Committee have pointed out that it is impossible to confirm that the thyroid abnormalities detected by the screening are related to radiation. The results of the 2020 edition of the survey released by the United Nations Scientific Committee on the Effects of Radiation (UNSCEAR) in March last year also pointed out that the occurrence of thyroid cancer in Fukushima Prefecture was not related to radiation.

In addition, the International Research Agency for Cancer (IARC) proposed in 2018 that thyroid screening in Fukushima Prefecture should return to normal, and thyroid cancer screening for asymptomatic patients should be avoided as much as possible. If you are concerned that people who have been exposed to radiation doses of 100–500 mSv have a higher chance of developing thyroid cancer, even asymptomatic people can be screened with the consent of the person concerned. If the radiation dose does not exceed 100mSv, but there is a personal need for screening, a screening pipeline should also be provided.

It is worth noting that, on the 19th of last month, when the accident at the Fukushima Daiichi Nuclear Power Plant was underage, the six parties who had undergone a large-scale thyroid screening test in Fukushima Prefecture and required surgery after the diagnosis sought compensation from Tokyo Electric Power Company. 16 million yen. This is believed to be the first instance of a lawsuit filed against TEPCO for thyroid cancer.

Politicians boycott the content of letters

At present, the Governor of Fukushima Prefecture Masao Uchihori, the current Minister of the Environment, Sou Yamaguchi, and others have publicly stated that it is inappropriate for five former Japanese Prime Ministers including Junichiro Koizumi to mention that " many children suffer from thyroid cancer " in their letters.

Sou Yamaguchi, Minister of the Environment, pointed out that the Fukushima Prefectural Health Survey Committee and the United Nations Scientific Committee on Radiation Effects ( UNSCEAR ) have both determined that the results of the thyroid test conducted by Fukushima Prefecture cannot be said to be affected by radiation. Suffering from thyroid cancer ” is likely to contribute to discrimination or prejudice against the citizens of Fukushima.

The Governor of Fukushima Prefecture, Masao Uchihori, emphasized that for the revival of Fukushima, he hoped that the five former Japanese prime ministers could release information based on scientific insights. If they want to describe the current situation of Fukushima, they should also add the opinions and specialized agencies of Fukushima Prefecture. Or the information assistance of international scientific institutions can objectively state the current situation of Fukushima.