To the Editor.—I am writing this letter because I was inspired by the editorial by Vicki J. Schnadig, MD.1 The children in Fukushima, Japan are in danger. In the thyroid screening program of the Fukushima Health Management Survey (FHMS), more than 200 children have received a diagnosis of thyroid cancer by ultrasonography (US) and fine-needle aspiration cytology, and most of them have already undergone surgery.2 The number is still increasing because there has been no change in the screening program since 2011. We must reconsider the natural history of thyroid cancer. There are 2 major theories about thyroid carcinogenesis: fetal cell carcinogenesis and early-onset multistep carcinogenesis.3 It should be noted that in both theories, early detection of thyroid cancer in children can be harmful because of either overdiagnosis or diagnosis too early.
Only a limited number of residents of Fukushima realize the risk of overdiagnosis in thyroid US screening because Fukushima Prefecture provides little information on possible negative effects of this program. Furthermore, the US examination is performed as one of the school programs.4 Thus, even though the local government insists that the participation of residents is voluntary, most of the children and their parents regard it as mandatory. In fact, the rate of participation by schoolchildren is more than 90%.
Only a few Japanese experts have reported on the possible harm caused by the FHMS, and there has been no recommendation to stop thyroid screening from related academic societies.5 This might be due to the following 2 reasons: First, the FHMS, which was planned by chief Japanese experts, was started as a large national project with a budget of up to $1 billion. Currently, there is an awkward atmosphere, with Japanese experts not willing to talk about the harm caused by this project. Second, as also happened in the case of Korea, numerous experts still do not understand the concept of overdiagnosis. They can see no harm in the early detection and treatment of cancer. Some say, “This should not be called overdiagnosis, since the FHMS helps to reduce the anxiety of residents.” Others say, “The harm caused by US thyroid screening in Fukushima is very limited, since the procedures are carried out with care.”
Overdiagnosis of thyroid cancer in Fukushima has occurred in the younger generation. The harm is more serious than that which occurred in Korea. The children who receive a diagnosis of thyroid cancer are regarded as patients with juvenile cancer. People usually regard juvenile cancer as a fatal disease. Thus, they must live the rest of their lives, probably more than half a century, as patients with a life-threatening disease. They may encounter unreasonable obstacles in choosing their schools, jobs, and even marriage partners. Overdiagnosis of thyroid cancer in the younger generation is not only a matter of their health but also human rights. I hope that foreign experts maintain their interest in this situation and provide good advice.
The author has no relevant financial interest in the products or companies described in this article.