Satoru Suzuki

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

UNLABELLED 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 Chernobyls 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 large-scaled 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.

Psychosocial Issues Related to Thyroid Examination After a Radiation Disaster

A thyroid ultrasound examination program has been conducted in the aftermath of the Fukushima Daiichi Nuclear Power Plant accident to address concerns about the increased risk of thyroid cancer similar to those experienced by local residents after the 1986 Chernobyl accident. This is the second-largest thyroid cancer screening in younger age ever, following only that conducted after Chernobyl. As the natural history of thyroid cancer in younger populations is not well characterized, large-scale screening using thyroid ultrasound could result in overdiagnosis, even with careful planning, as has been experienced in South Korea. Awareness regarding the thyroid gland is generally low among residents, who tend to directly associate examination results with radiation exposure and are likely to develop newfound anxiety and feelings of self-condemnation and guilt. We reviewed the dilemma surrounding cancer screening and particularly underscored the need to address psychosocial issues associated with possible overdiagnosis. We modified our approach to address individual and social anxiety induced by results of screening conducted after the Fukushima accident. These findings and our experiences regarding the psychosocial issues related to thyroid examination should assist residents in their lifelong decision making and help them prepare for future disasters.

Comparison of childhood thyroid cancer prevalence among 3 areas based on external radiation dose after the Fukushima Daiichi nuclear power plant accident: The Fukushima health management survey

AbstractThe 2011 Great East Japan Earthquake led to a subsequent nuclear accident at the Fukushima Daiichi Nuclear Power Plant. In its wake, we sought to examine the association between external radiation dose and thyroid cancer in Fukushima Prefecture. We applied a cross-sectional study design with 300,476 participants aged 18 years and younger who underwent thyroid examinations between October 2011 and June 2015. Areas within Fukushima Prefecture were divided into three groups based on individual external doses (≥1% of 5 mSv, <99% of 1 mSv/y, and the other). The odds ratios (ORs) and 95% confidence intervals of thyroid cancer for all areas, with the lowest dose area as reference, were calculated using logistic regression models adjusted for age and sex. Furthermore, the ORs of thyroid cancer for individual external doses of 1 mSv or more and 2 mSv or more, with the external dose less than 1 mSv as reference, were calculated. Prevalence of thyroid cancer for the location groups were 48/100,000 for the highest dose area, 36/100,000 for the middle dose area, and 41/100,000 for the lowest dose area. Compared with the lowest dose area, age-, and sex-adjusted ORs (95% confidence intervals) for the highest-dose and middle-dose areas were 1.49 (0.36–6.23) and 1.00 (0.67–1.50), respectively. The duration between accident and thyroid examination was not associated with thyroid cancer prevalence. There were no significant associations between individual external doses and prevalence of thyroid cancer. External radiation dose was not associated with thyroid cancer prevalence among Fukushima children within the first 4 years after the nuclear accident.

Systematic determination of thyroid volume by ultrasound examination from infancy to adolescence in Japan: The Fukushima Health Management Survey

Although several reports have defined normal thyroid volume depending on either age or body surface, there are no sequential reference values on childhood thyroid volume evaluated by using ultrasonography and epidemiological analysis in Japan. The aim of the present study was to establish updated reference values for thyroid volume by ultrasound examination and epidemiological analysis in 0-19 year-old Japanese children. It is based on a cross-sectional study conducted from October 9, 2011 to March 31, 2012. The subjects were 38,063 children who were examined by ultrasonography as the initial preliminary survey of the Fukushima Health Management Survey in October 9, 2011 to March 31, 2012. The width, thickness, and height of each lobe were measured and the volume of each lobe was calculated by the mean of the elliptical shape volume formula. The values of thyroid volume at the 2.5 and 97.5 percentiles of age and body surface area for each gender group were obtained from 0-19 year-old children. Positive correlation was observed between thyroid volume and either age or body surface. The right lobe was significantly larger than the left lobe. The thyroid volume in females was larger than that in males after adjusting body surface area. The reference values of childhood thyroid for each age or body surface area were obtained by this extensive survey using ultrasound. These reference values may be used to define the normal size of thyroid gland by echosonography in Japanese children, although thyroid volume may be affected by dimorphic factors such as sex hormones.

Comprehensive Health Risk Management after the Fukushima Nuclear Power Plant Accident

Five years have passed since the Great East Japan Earthquake and the subsequent Fukushima Daiichi Nuclear Power Plant accident on 11 March 2011. Countermeasures aimed at human protection during the emergency period, including evacuation, sheltering and control of the food chain were implemented in a timely manner by the Japanese Government. However, there is an apparent need for improvement, especially in the areas of nuclear safety and protection, and also in the management of radiation health risk during and even after the accident. Continuous monitoring and characterisation of the levels of radioactivity in the environment and foods in Fukushima are now essential for obtaining informed consent to the decisions on living in the radio-contaminated areas and also on returning back to the evacuated areas once re-entry is allowed; it is also important to carry out a realistic assessment of the radiation doses on the basis of measurements. Until now, various types of radiation health risk management projects and research have been implemented in Fukushima, among which the Fukushima Health Management Survey is the largest health monitoring project. It includes the Basic Survey for the estimation of external radiation doses received during the first 4 months after the accident and four detailed surveys: thyroid ultrasound examination, comprehensive health check-up, mental health and lifestyle survey, and survey on pregnant women and nursing mothers, with the aim to prospectively take care of the health of all the residents of Fukushima Prefecture for a long time. In particular, among evacuees of the Fukushima Nuclear Power Plant accident, concern about radiation risk is associated with psychological stresses. Here, ongoing health risk management will be reviewed, focusing on the difficult challenge of post-disaster recovery and resilience in Fukushima.

Prevalence of thyroid nodular lesions in children and adolescents

Department of Laboratory Medicine, Department of Thyroid and Endocrinology, Department of Radiation Health Management, Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University, Fukushima, Japan, Department of Global Health, Medicine and Welfare, Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan, Department of Clinical Studies, Radiation Effects Research Foundation, Nagasaki, Japan, Department of Social Medicine, Department of Emergency and Disaster Medicine, Department of Endocrinology and Metabolism, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan, Third Department of Internal Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan, Department of Social Medicine, Department of Clinical Laboratory Medicine, Jichi Medical University, Tochigi, Japan, The First Department of Medicine, Wakayama Medical University, Wakayama, Japan Division of Endocrinology and Metabolism, Showa General Hospital, Tokyo, Japan

Comparative Analysis of the Growth Pattern of Thyroid Cancer in Young Patients Screened by Ultrasonography in Japan After a Nuclear Accident: The Fukushima Health Management Survey

Importance Thyroid cancer generally grows at a very slow rate in adults, and overdiagnosis is a global issue. However, the detection of early-stage thyroid cancer by screening is not well described in young patients. To prevent overdiagnosis, it is essential to understand the natural course of thyroid cancer growth detection by ultrasonography screening in young patients. Objective To evaluate the natural progression of thyroid cancer in young patients. Design, Setting, and Participants An observational study evaluated changes in the diameter of malignant or suspected malignant thyroid tumors on 2 occasions. Changes in malignant thyroid tumor diameter were estimated during the observation period between the screening and confirmatory examinations in the first-round thyroid ultrasonography examination of the Fukushima Health Management Survey in patients younger than 21 years after a nuclear accident at a power plant in Fukushima, Japan. In total, 116 patients cytologically diagnosed with or suspected to have thyroid cancer were classified into 3 groups based on a greater than 10% reduction, a change of −10% to +10% in diameter, and a greater than 10% increase in tumor diameter. The association between tumor growth rate and tumor diameter was analyzed. The study was conducted from March 1, 2016, to August 6, 2017. Main Outcomes and Measures Tumor volume changes, the coefficient of growth of thyroid cancer in young patients, and the association between the observation period or tumor diameter and them. Results Of 116 patients, 77 were female; the mean age was 16.9 years (median, 17.5 years). The mean observation period was 0.488 (range, 0.077-1.632) years. No significant differences in age, sex, tumor diameter, observation period, or serum levels of thyrotropin and thyroglobulin were observed among the groups. Whereas tumor volume changes were not linearly correlated with the observation period (Pearson R = 0.121; 95% CI, −0.062 to 0.297), the coefficient of growth was significantly and negatively correlated with the tumor diameter in the screening examination (Spearman &rgr; = −0.183; 95% CI, −0.354 to −0.001), suggesting growth arrest after the initial proliferation phase. Conclusions and Relevance Ultrasonography screening could reveal asymptomatic thyroid cancer that is falling into a growth arrest pattern in many young patients. Considering the long life expectancy, prevention of overdiagnosis necessitates careful long-term monitoring without immediate diagnosis for suspected noninvasive thyroid cancer.

Findings of Thyroid Ultrasound Examination Within 3 Years After the Fukushima Nuclear Power Plant Accident: The Fukushima Health Management Survey

Context Childhood thyroid cancer is of great concern after the Fukushima nuclear power plant accident. Baseline analytical data on thyroid ultrasound examination (TUE) in children are important for future studies. Objective We analyzed the age and sex distribution of findings from the TUEs of children and adolescents in the Fukushima Health Management Survey (FHMS). Design, Setting, and Participants From October 2011 through March 2014, 294,905 participants aged 18 years or younger at the time of the earthquake voluntarily had TUEs in the first round of the FHMS. A secondary confirmatory examination was performed in 2032 subjects. Age- and sex-dependent prevalence and size of thyroid cysts, nodules, and cancers were analyzed. Main Outcome Measures Age, sex, and size distribution of findings were analyzed. Results Thyroid cysts, nodules, and cytologically suspected cancers were detected in 68,009, 1415, and 38 male subjects and in 73,014, 2455, and 74 female subjects, respectively. There was an age-dependent increase in the detection rate of thyroid nodules and cancer, but that of cysts reached a peak at 11 to 12 years. Sex affected the prevalence of thyroid nodules and cancers after the onset of puberty, but only a small difference was exhibited in that of cysts. Conclusions The thyroid cancer detection rate in Fukushima was clarified, and the proportion of individuals with thyroid nodules and cysts varied substantially by age. The results of this study will contribute to future epidemiological research on nodular thyroid diseases in children and adolescents.

Psychosocial Impact of the Thyroid Examination of the Fukushima Health Management Survey

The thyroid examination component of the Fukushima Health Management Survey was launched in a chaotic environment with insufficient preparation following a compound disaster in 2011. Over the past 5 years, various psychosocial issues have arisen related to these ultrasound examinations. Examinees and their families tended to associate examination results with radiation exposure and developed new concerns about thyroid cancer. Screening for thyroid cancer is not generally recommended around the world, owing to the disease’s excellent prognosis and to risk of overdiagnosis. We reevaluated the thyroid examination program in terms of screening principles and in consideration of the situation after a nuclear power plant accident. We found the program does not match the principles for planning of case-finding and inadequately balances potential benefits and harms. To address various psychosocial issues and reduce harm related to thyroid examinations we have provided explanatory meetings, individual counseling, and classes for students. These strategies are essential, yet they are also insufficient. More extensive program changes are necessary to further reduce the potential harms of thyroid cancer screening and related negative experiences.

Five-Year Interim Report of Thyroid Ultrasound Examinations in the Fukushima Health Management Survey

Abstract The thyroid ultrasound examination in the Fukushima Health Management Survey consists of two stages: the primary examination focuses mainly on nodules and cysts; and the confirmatory examination is for individuals who may need detailed follow-up. According to the data up until March 2016, 116 individuals were diagnosed with malignancy or suspected malignancy in the preliminary baseline survey from fiscal year (FY) 2011 to FY2013. In the second-round thyroid examination in FY2014 and FY2015, confirmatory examinations are currently in progress: at this stage, 57 individuals have been diagnosed with malignancy or suspected malignancy. The number of detected thyroid cancer cases was age dependent in both the first- and second-round examinations. Exposure to radiation from the Fukushima accident is unlikely to have produced this marked increase in thyroid cancer rate compared with the previous cancer registry, when no thyroid cancer screening was implemented. This finding suggests overdiagnosis due to screening effects over the past 5 years.