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Comment & Response
June 13, 2019

Incidence of Thyroid Cancer Among Children and Young Adults in Fukushima, Japan—Reply

Author Affiliations
  • 1Department of Radiation Health Management, Fukushima Medical University, Fukushima, Japan
  • 2Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima, Japan
  • 3National Institute of Public Health, Saitama, Japan
  • 4Hiroshima University, Hiroshima, Japan
JAMA Otolaryngol Head Neck Surg. Published online June 13, 2019. doi:10.1001/jamaoto.2019.1102

In Reply In our observational study,1 we comprehensively assessed the characteristics of thyroid cancer screened by ultrasonography among children and young adults with 2 rounds of examination during the first 5 years after the 2011 Fukushima Daiichi nuclear power station accident.

The article by Takahashi et al2 that Suzuki et al referred to was a simulation study of anticipated childhood and adolescent thyroid cancer cases in Japan that used a cancer progression model based on the National Cancer Registry. However, Figure 1 in our study was not based on the simulation model but on the exact detected cases in the thyroid examinations, the values of which were adjusted for the number of participants in each age group at the time of the accident. Suzuki et al highlighted the following 2 concerns: (1) goodness of fit should be shown and (2) detectable incidence function J(s) should be specifically checked to see whether or not it is dependent on age with evidence. Although these factors are significant for further analysis based on the simulation model, a recent analysis showed that ultrasonography screening–detected thyroid cancers do not have a linear progression but fall into a growth arrest in many young patients.3 Thus, future studies will be conducted to run simulation models based on theoretically reasonable tumor growth patterns of thyroid cancer in young patients based on ultrasonographic observation data from the Fukushima cohort.