The protocol and preliminary baseline survey results of the thyroid ultrasound examination in Fukushima [Rapid Communication]

Abstract

Abstract. After the Fukushima nuclear power plant accident on March 11, 2011, the public of Japan became particularly concerned about the possibility of an increased risk of childhood thyroid cancer, similar to what was observed after the Chernobyl's accident. Due to serious public health perception, there was an urgency to evaluate the baseline levels of childhood thyroid status in Fukushima prefecture. Therefore we have commenced a thyroid ultrasound examination (TUE) survey of the approximately 360,000 pediatric inhabitants (0 to 18 years of age) who lived in Fukushima at the time of the accident in October 2011. The subjects were divided into three categories according to the standardized diagnostic criteria of ultrasound findings. Category A contained the subjects whose TUE findings were intact or benign. Category B were recommended a confirmatory TUE. Category C was recommended an immediate confirmatory TUE. Results: The survey of 40,302 subjects in the first year was completed in March, 2013. There were 40,097 (99.5%), 205 (0.50%) and 0 subjects in categories A, B and C, respectively. Of the 82 category B subjects who underwent fine needle aspiration cytology (FNAC), 12 were diagnosed with a malignant tumor or were suspected to have malignancy. The 12 subjects received thyroid surgery and 11 thyroid cancers and one benign nodule were confirmed histologically after surgery. This is the first largescaled TUE survey to employ sophisticated ultrasound screening and aim to evaluate the baseline frequency of childhood thyroid nodules and cysts. The results will become the golden standard of future comparative TUE in Fukushima, Japan.Key words: Fukushima, Chernobyl, Ultrasound examination, Nodules, Thyroid cancer first few months after the Fukushima disaster.Due to the issue of concern and a strong request from the central and local governments, the Fukushima Health Management survey (FHM) body initiated several health protection surveys [5], including one that involved thyroid ultrasound examinations (TUE) of all pediatric inhabitants who lived or were staying in Fukushima at the time of the accident. The first objective of this survey was to evaluate the baseline rates of childhood thyroid nodules and cancer in Fukushima as this information was not yet available. The baseline survey commenced on October 9, 2011 [6,7] and was conducted by Fukushima Medical University (FMU). Since it is essentially important to follow the standardized ultrasound diagnostic criteria as a part of quality control when any large-scaled screening, the protocol and the initial data of the baseline TUE survey in Fukushima are reported concretely here for the first time.

Ultrasound and the Evaluation of Pediatric Thyroid Malignancy: Current Recommendations for Diagnosis and Follow‐up

“…The physical examination failed to identify any of the 11 nodules larger than 1 cm, including 2 nodules in the radiation group with suspicious US characteristics that were later diagnosed as malignancies requiring surgery . Although the survivability of pediatric thyroid cancer is generally good, the risk of death associated with thyroid cancer when it has developed as a second primary malignancy is 3 to 6 times greater . Such thyroid cancers are also more likely to be multifocal and smaller than 1 cm …”

“…Another example is second primary cancers, which are those that develop after an initial cancer of any type. Most contemporary cases of second primary pediatric thyroid malignancy are attributed to prior head and neck radiation for malignancy or exposure to nuclear fallout . In contrast to the indolent and rarely fatal course of most primary thyroid malignancies, these secondary cancers are more likely to be multifocal at the time of diagnosis and confer a 3‐ to 6‐fold higher risk of mortality …”

“…Highlights of pediatric thyroid US findings can be found in recent national guidelines, original scientific publications, and book chapters . More recent investigations focused on the accuracy of modern US in diagnosing thyroid malignancy in children, as well as the implementation of screening US for thyroid cancer in higher‐risk populations …”

Histopathological analysis of papillary thyroid carcinoma detected during ultrasound screening examinations in Fukushima

“…However, an uncertainty in potential exposure doses during the acute phase of the crisis in Fukushima and the experience of Chernobyl, after which a sharp increase in thyroid cancer incidence in children from the most affected regions was observed, led to the launch of the Fukushima Health Management Survey program . One of 4 detailed surveys, the Thyroid Ultrasound Examination (TUE) was started in October 2011 . The aim of TUE was to undertake ultrasound screening of all children and adolescents of Fukushima Prefecture aged 18 years or younger as of April 1, 2011 (367 649 persons).…”

“…8 One of 4 detailed surveys, the Thyroid Ultrasound Examination (TUE) was started in October 2011. 9 The aim of TUE was to undertake ultrasound screening of all children and adolescents of Fukushima Prefecture aged 18 years or younger as of April 1, 2011 (367 649 persons).…”