S. Suzuki et al. for the Fukushima Health Management Survey (FHMS) concluded that the high prevalence of childhood thyroid cancer detected in the first four years in Fukushima can be attributed to mass screening.1 One reason for this was a striking discrepancy in age distribution of cancer patients in Fukushima within 0-3 years following exposure versus similar data in Ukraine 4-7 years after exposure.2 Their circuitous comparison seems to be because they consider thyroid cancer patients detected during latency period in Chernobyl were not due to radiation. On this assumption, thyroid cancers detected in Fukushima in 0-3 years after exposure can never be radiation induced, as FHMS names the first thyroid examination “Preliminary Baseline Screening”.3 This idea is widely spread and adopted in IAEA 2013 report: thyroid cancers in Fukushima are unlikely to be radiation induced because no case was found in the age of 0–5 years at exposure. 4
They did not argue that thyroid cancers found in Fukushima are not radiation induced because cancers were found in latency (A in Figure), but they took a more circuitous way (B): Because the age pattern of thyroid cancers in Fukushima in 0-3 years after exposure is different from the one of radiation induced cancer of Ukraine in 4-7 years, thyroid cancers in Fukushima in 0-3 years are not radiation induced. The criterion B for radiation induced thyroid cancer seems to be a kind of trick (deception) because it is equivalent to a criterion that thyroid cancers diagnosed in 0-3 years are not due to exposure. FHMS had this conclusion from the beginning of thyroid examination.
Latency period of radiation induced thyroid cancer may distribute and depend on the extent of exposure and patient’s age. Thyroid cancer cases growing quickly in sensitive children of high dose may contribute cases in 0-3 years after exposure. The striking similarity between age patterns during 4 years after exposure in Ukraine and in Fukushima2 suggests similar character of thyroid cancer in both areas.
Those younger than five years at exposure were considered to have the highest risk for thyroid cancer in Ukraine.2 This is not correct because the average numbers of patients per age during 4-7 years for ages 0-4 and 5-18 at exposure were 14.2 and 23.1 cases, respectively. (FIG. 1) The former is 60 % of the latter. Age distributions of thyroid cancer patients after Chernobyl accident are different in three countries, and this shall be examined next. ４４８
２０１６年９月開催「第５回福島国際専門家会議」 S. Suzuki'Correspondence information about the author S. Suzuki
・Childhood and Adolescent Thyroid Cancer in Fukushima after the Fukushima Daiichpermalink.phpi Nuclear Power Plant Accident: 5 Years On S. Suzuki Clinical Oncology 2016
・Childhood Thyroid Cancer in Belarus, Russia, and Ukraine after Chernobyl and at Present YURI E. DEMIDCHIK, VLADIMIR A. SAENKO, SHUNICHI YAMASHITA
・Age Distribution of Childhood Thyroid Cancer Patients in Ukraine After Chernobyl and in Fukushima After the TEPCO-Fukushima Daiichi NPP Accident
Mykola D. Tronko,1 Vladimir A. Saenko, Victor M. Shpak,1 Tetiana I. Bogdanova,1 Shinichi Suzuki,3 and Shunichi Yamashita