Overdiagnosis of Juvenile Thyroid Cancer

Abstract

Overdiagnosis is the detection of a disease that does not do any harm to the patient throughout the lifetime. Thyroid cancer in children is a rare disease; however, since 2011, many children in Fukushima, Japan, have been diagnosed with it, and the number has shown a steady increase to over 200 cases at present. Some experts have stated that this phenomenon is due to overdiagnosis caused by thyroid ultrasound (US)-based thyroid screening detecting self-limiting thyroid cancer, which will not lead to clinical symptoms in the future. Harm caused by overdiagnosis of thyroid cancer is more serious in the young, since it is difficult to perform active surveillance and children diagnosed with cancer are likely to suffer from stigma. Thus, overdiagnosis of thyroid cancer in the young is not only a health problem but also a problem of human rights. Conflicts of interest among people related to screening programs and some experts with incomplete knowledge on overdiagnosis help to spread misleading opinions together with fear of radiation exposure among residents, which has led to their erroneous understanding of the nature of US-based thyroid screening. Scien-tific and honest discussions among experts to enhance education of residents and consideration of medical ethics are crucial to prevent the expansion of overdiagnosis.

In Reply

“…Thyroid examination is the cause of anxiety in Fukushima. 2 The need for psychological care during the secondary confirmatory examination described in this letter confirms that the examination is traumatic for the children and their parents. Furthermore, introduction of population-based thyroid screening for anxiety relief cannot be ethically justified because those who are worried are usually the parents, not their children who are under the threat of overdiagnosis.…”

“…Although thyroid radiation doses in Fukushima were thought to be relatively low, individual organ-specific measurements were rare, so a degree of uncertainty remains. A recent report 2 suggests the possibility of radiation-induced risks in pediatric thyroid carcinoma in Fukushima. Accordingly, most Japanese scientists and local stakeholders feel that health effects associated with radionuclides released by our nuclear plant accident have not been scientifically excluded, and that at least 10 years will be needed to determine whether increased risk of pediatric thyroid cancer is present.…”

“…A small surgery cannot save the children, and surgery too early can result in a high recurrence rate. 2 Addressing the anxiety of Fukushima residents and assessing the health effects of radiation are important. However, we should not overlook the fact that in the present program, this has been accomplished by sacrificing children's health.…”

Lessons learned from conducting disease monitoring in low-dose exposure conditions as a counter-measure after a nuclear disaster

“…Considering these results together, most papillary thyroid cancers are characterized by self-limiting growth in a growth arrest pattern, forming a large pool of latent cancer as a reservoir that cannot be detected without screening ( Fig. 1 ) [ 10 , 15 , 33 , 34 ]. It is thought that most papillary thyroid cancers show a self-limiting course like type ① in the figure.…”

Trends in Childhood Thyroid Cancer incidence in Korea and Its Potential Risk Factors

“…Our research team previously reported an increasing trend of childhood thyroid cancer in Korea until 2012 and since most children are not screened for thyroid cancer, 72% of childhood thyroid cancers were detected by palpation rather than screening (14). However, some experts stated that the increased incidence of childhood thyroid cancer is due to overdiagnosis by US-based screening (15).…”