Comparison of Thyroid Cancer Patient’s Clinical Data after Fukushima and Chernobyl Accidents.

  • The incidence of differentiated thyroid cancer  (DTC) increases steadily during the last 30 years worldwide. Screening effects, diagnostic improvements or real rise in incidence as a result of unknown carcinogens are discussed. Studies in post-Chernobyl pediatric DTC showed that the synergistic influence of radiation and nitrates may lead to an increased risk (Drozd et al., 2015).   For better understanding of the etiology, we compared the published clinical data of pediatric DTC patients after the nuclear emergency of Fukushima with the observations we made after the Chernobyl accident.

    In a large-scale survey after the Fukushima accident, 300,476 subjects were screened and 152 thyroid cancers were confirmed. Mean age of patients at diagnosis was 17.8 years, mean tumor size 14.9 mm. Postoperative lymph node metastasis, extra-thyroidal invasion, and pulmonary metastasis were detected in 79%, 45%, and 2.1% of all cases, respectively. Moreover only 4.8% cases were staged as pT1aN0M0.  (Suzuki et al., 2018).  For comparison, in Belarus patients mean age was 13.0 years at presentation, mean tumor size 14.4 mm. Lymph node metastases were observed in 74%, pulmonary metastasis  in 11% and  extra-thyroidal extension in 48.5- 64.1 (with respect to latency period) (Fridman et al., 2014).

    Lymph node metastases were discovered in patients from Japan and Belarus more than 70% meaning  that most of cancers  were clinically significant and not “overdiagnosed”. Given that the thyroid doses were low in Japanese cases, it would be interesting to evaluate and compare the exposure to endocrine disruptors as e.g. nitrates in patients from both countries.

 

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