CURRENT STATUS OF PEDIATRIC THYROID CANCER 14 YEARS AFTER THE FUKUSHIMA NUCLEAR ACCIDENT

Abstract

Following the Fukushima Daiichi nuclear power plant accident associated with the Great East Japan Earthquake in 2011, thyroid cancers were detected through population-based ultrasound screening. We herein describe the clinicopathological features of these thyroid cancers. The mean age at the time of the accident was 17.8 years, with a male-to-female ratio of 1:1.8. Lymph node metastasis was detected in 22.4% of cases preoperatively, but this increased to 77.6% in postoperative pathological examinations, predominantly involving peritracheal nodes. Extrathyroidal extension was observed in 39% of cases, and distant metastasis (M1) was found in 2.4%. The surgical procedures performed included total thyroidectomy in 8.8% and lobectomy in 91.2%, with lymph node dissection performed in all cases. Histopathology revealed that 98% of cases were papillary carcinoma. Genetic analysis demonstrated BRAF mutations in 69% of cases, whereas RET/PTC3 rearrangements were rare, showing a distinct pattern compared with Chernobyl. In summary, thyroid cancers detected in Fukushima differed significantly from those after the Chernobyl accident. Except for sex distribution, the clinical features were similar to those of both adult and pediatric sporadic thyroid cancers.