Prevalence of thyroid diffuse goiter and its association with body mass index and the presence of cysts and nodules in children and adolescents: the Fukushima Health Management Survey.

The main cause of diffuse thyroid goiter is autoimmune chronic thyroiditis, otherwise known as Hashimoto's thyroiditis. Thyroid hormones play pivotal roles in growth and development during childhood. However, the prevalence of diffuse goiter and the relationships between diffuse goiter, thyroid volume, cysts and nodules, and anthropometric measurements in children are not well known. Among 789,459 participants who participated in thyroid ultrasound examinations, 320,206 participants (male: 161,728; female: 158,478) aged 1-23 years were analyzed. Logistic regression analyses were conducted to calculate the odds ratios of the standard deviation score of body mass index (BMI-SDS), the SDS of bilateral width multiplied thickness area (BWTAR-SDS) as a provisional determination of thyroid volume, and the presence of nodules or cysts for positive diffuse goiter compared with negative diffuse goiter after correction for sex and age. The prevalence of diffuse goiter increased in a female-dominant manner with aging. Compared with the absence of diffuse goiter, the age- and sex-adjusted odds ratios (95% confidence intervals) for BMI-SDS (1 SD), BWTAR-SDS (1 SD), cysts, and nodules were 1.24 (1.21-1.27), 3.21 (3.13-3.29), 0.53 (0.50-0.58), and 1.38 (1.17-1.64), respectively. The odds ratios of nodules for positive diffuse goiter were 4.18 (1.08-16.08), 1.76 (1.01-3.07), 1.80 (1.32-2.45), and 1.34 (1.08-1.67) in the age groups 1-7, 8-11, 12-15, and 16-23 years, respectively. The age-dependent increase in the prevalence of diffuse goiter was independently associated with increased BMI and positive prevalence of nodules in young individuals.

Confounding factors and biases involved in regional differences in the detection rate of thyroid cancer in the second-round Thyroid Ultrasound Examination: the Fukushima Health Management Survey.

In response to concerns about health due to radiation exposure, the Fukushima Prefecture launched the Thyroid Ultrasound Examination program for residents aged 0-18 years at the time of the earthquake. Herein, we considered the confounding factors involved in the regional differences in the development of thyroid cancer. In this study, the 242 065 individuals who participated in both first- and second-round surveys were classified into four groups by address according to their air radiation dose. The number of participants diagnosed as malignant or suspicious for malignancy by cytological examination were 17, 38, 10 and 4 with detection rates of 53.8, 27.8, 21.7 and 14.5 per 100 000 participants in Regions 1, 2, 3 and 4, respectively. Sex (P = 0.0400), age at the time of the primary examination (P < 0.0001) and interval between the first- and second-round surveys (P < 0.0001) were significantly different among the four regions, and these were suspected to be confounding factors affecting regional differences in malignant nodule detection rates. In addition, significant regional differences were observed in the participation rate in the confirmatory examination (P = 0.0037) and the fine needle aspiration cytology implementation rate (P = 0.0037), which could be potential biases. No significant regional differences in the detection of malignant nodules were found in the multivariate logistic regression analysis after adjusting for the survey interval alone or for sex, age and survey interval. The confounding factors and biases identified in this study that may have important impacts on thyroid cancer detection rate should be fully considered in future studies.

A Comprehensive Review of the Progress and Evaluation of the Thyroid Ultrasound Examination Program, the Fukushima Health Management Survey.

The Great East Japan Earthquake on March 11, 2011, and the subsequent tsunami caused an accident at the Fukushima Daiichi Nuclear Power Plant, in which extensive damage to the nuclear power reactors resulted in massive radioactive contamination. Fukushima Prefecture implemented the Thyroid Ultrasound Examination (TUE) program as part of the Fukushima Health Management Survey project in response to residents' anxieties about health risks due to radiation exposure for residents aged 0-18 years at the time of the nuclear accident. This program consisted of the primary examination and the confirmatory examination. In the primary examination, thyroid nodules and cysts were examined using portable ultrasound apparatuses. The confirmatory examination was performed to have clinical or cytological diagnosis. As of June 30, 2021, 116, 71, 31, 36, and 9 examinees in the first, second, third, and fourth round of surveys, and the survey at age 25 years, respectively, were determined to have nodules cytologically diagnosed as malignant or suspicious for malignancy. The confirmatory examination of the fourth-round survey and the primary and confirmatory examination of fifth-round survey are currently in progress. Together with the low thyroid absorbed radiation dose estimated in the United Nations Scientific Committee on the Effects of Atomic Radiation 2020 report, our results suggested that the increased incidence of childhood thyroid cancer in Fukushima Prefecture was not caused by radiation exposure, but rather by the highly sensitive detection method. As detailed in this review, there were ongoing challenges in our program, such as actions against the risk of overdiagnosis and psychological support for participants and their families.

Revisiting the Geographical Distribution of Thyroid Cancer Incidence in Fukushima Prefecture: Analysis of Data From the Second- and Third-round Thyroid Ultrasound Examination.

BACKGROUND: After the first-round (Preliminary Baseline Survey) ultrasound-based examination for thyroid cancer in response to the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, two rounds of surveys (Full-scale Survey) have been carried out in Fukushima Prefecture. Using the data from these surveys, the geographical distribution of thyroid cancer incidence over 6 or 7 years after the disaster was examined. METHODS: Children and adolescents who underwent the ultrasound-based examinations in the second- and/or third-round (Full-scale) survey in addition to the first-round survey were included. With a discrete survival model, we computed age, sex, and body mass index standardized incidence ratios (SIRs) for municipalities. Then, we employed spatial statistics to assess geographic clustering tendency in SIRs and Poisson regression to assess the association of SIRs with the municipal average absorbed dose to the thyroid gland at the 59-municipality level. RESULTS: Throughout the second- and third-round surveys, 99 thyroid cancer cases were diagnosed in the study population of 252,502 individuals. Both flexibly shaped spatial scan statistics and maximized excess events test did not detect statistically significant spatial clustering (P = 0.17 and 0.54, respectively). Poisson regression showed no significant dose-response relationship: the estimated relative risks of lowest, middle-low, middle-high, and highest areas were 1.16 (95% confidence interval [CI], 0.52-2.59), 0.55 (95% CI, 0.31-0.97), 1.05 (95% CI, 0.79-1.40), and 1.24 (95% CI, 0.89-1.74). CONCLUSION: There was no statistical support for geographic clustering or regional association with radiation dose measures of the thyroid cancer incidence in the cohort followed up to the third-round survey (fiscal years 2016-2017) in Fukushima Prefecture.

Possible Association Between Thyroid Nodule Formation and Developmental Alterations in the Pituitary-Thyroid Hormone Axis in Children and Adolescents: The Fukushima Health Management Survey.

Background: We previously found low thyrotropin (TSH) levels in children and adolescents with thyroid nodules, including papillary thyroid cancer, although it is generally accepted that high TSH levels are a risk factor for formation and growth of thyroid nodules in adults. To clarify the reasons for the discrepancy, we precisely analyzed the features of pituitary-thyroid hormone (TH) actions in children and adolescents with or without nodules at different ages. Methods: Among the 4955 participants who participated in a second screening by thyroid ultrasound examination in the Fukushima Health Management Survey, 721 and 2849 euthyroid participants aged 6-20 years without or with nodules, including thyroid cancer, were selected for evaluation of TH regulation. The responsivity of TSH to THs was assessed by two thyroid feedback quantile-based indices (T4FQI and T3FQI). Logistic regression analyses were conducted to calculate the odds ratios (ORs) of serum concentrations related to thyroid functions for positive thyroid nodules compared with negative nodules. Results: The feedback indices declined in a sex-specific manner with aging. In particular, T3FQI, the index for TSH response to free triiodothyronine (fT3), started to decline after ∼10 and 15 years of age in female and male participants, respectively. Compared with the absence of nodules, the age- and sex-adjusted ORs (confidence intervals) for logTSH, free thyroxine (fT4), fT3, T4FQI, T3FQI, and thyroglobulin levels were 0.586 (0.501-0.685), 1.036 (0.595-1.805), 1.059 (0.842-1.332), 0.569 (0.454-0.715), 0.564 (0.443-0.719), and 1.01 (1.005-1.014), respectively. Associations between the presence of nodules and either low logTSH or low feedback indices were observed in participants aged between 12 and 17 years among the total cohort. Conclusions: The relationships between the levels of TSH and THs changed in a sex-dependent manner in children and adolescents. The age-dependent shift in the pituitary-TH set point may be associated with age-dependent nodule formation during restricted periods of growth and maturation in both young female and male participants.

Demographic characteristics of children with growth hormone deficiency from 1996 to 2015 in Japan: 20 years of data from the foundation for growth science in Japan.

Growth hormone (GH) deficiency (GHD) in children is a heterogeneous condition that includes several entities of various severities. GH treatment has been affected by various factors. Because comprehensive analyses for Japanese children with GHD over time are scarce, we investigated the baseline characteristics of patients with GHD at the start of GH treatment between 1996 and 2015 using data from the Foundation for Growth Science in Japan. During the registration period, 19,717 subjects were determined to be eligible for GH treatment as GHD. Overall analyses revealed that there were twice the number of male patients as female patients, and the etiology was idiopathic in 91.1%, central nervous system (CNS) tumor at the hypothalamus-pituitary area in 1.7%, CNS tumor distant from the hypothalamus-pituitary area in 0.68%, other tumors in 0.91%, congenital CNS malformations in 0.83%, and other diseases in 1.1% with their specific characteristics. The latest average age, height standard deviation score (SDS), insulin-like growth factor-1 SDS, and proportion of severe GHD at GH treatment initiation were 8.8 years, -2.76, -1.42, and 19.5%, respectively. The proportions of breech delivery and asphyxia gradually decreased, whereas that of caesarean section gradually increased during the registration period with the latest values of 2.2%, 4.9%, and 14.0%, respectively (all analyses: p < 0.0001). In contrast, the proportion of idiopathic GHD with breech delivery seemed to reach the lowest level among those with a birth year before 2000. This study identified the characteristics and changes of patients with GHD over 20 years.

Preschool-children's height, trend, and causes: Japanese national surveys 1990-2010.

We observed trends in the height of children aged 3 to 6 in Japan using data from the National Growth Survey on Preschool Children in the years 1990, 2000, and 2010. Average standard deviation (SD) scores of height decreased from 0.39 (SD 1.02) in 1990 (n = 3,684) to 0.37 (SD 1.05) in 2000 (n = 2,981) and 0.33 (SD 1.07) in 2010 (n = 2,027). Mothers of children in later waves were taller, older, and more likely to be primiparous; children in later waves had shorter gestational age, lower birth weight, and were less likely to have been fed less with formula or solid foods before 6 mo. The only factor that consistently contributed to a reduction in children's height for both 1990-2000 and 2000-2010 was a reduction in birthweight SD score (indirect effect on height -1.5 [95% CI: -1.9, -1.1] mm for 1990-2000 and -1.2 [95% CI: -1.8, -0.8] mm for 2000-2010). Factors that contributed, although not significantly or consistently between the two periods, were changes in pre-pregnancy BMI, smoking during pregnancy, multiple pregnancies, gestational age, BMI at birth, and use of formula and solid foods before 6 mo. Secular increases in maternal age, height, and primiparity contributed to increasing children's height.

Fine Needle Aspiration Cytology Implementation and Malignancy Rates in Children and Adolescents Based on Japanese Guidelines: The Fukushima Health Management Survey.

Background: The thyroid ultrasound examination (TUE) program was initiated among the residents of Fukushima Prefecture aged ≤18 years at the time of the Fukushima Dai-ichi Nuclear Power Plant accident. In this program, fine needle aspiration cytology (FNAC) was performed only in cases that conformed to the Japanese guidelines for the management of thyroid nodules. To analyze the suitability of the protocol in the TUE, we analyzed the implementation rate of FNAC and the detection rate of thyroid malignancy. Methods: There were 299,939 and 269,659 voluntary participants in the Preliminarily Baseline Survey (PLBS), first-round survey, and the first Full-scale Survey (FSS), second-round survey, of the TUE, respectively. FNAC is recommended for nodules with diameters 5.1-10.0 mm showing sonographic characteristics that are strongly suspicious for thyroid carcinoma; diameters 10.1-20.0 mm with characteristics that are suspicious for carcinoma; and all nodules with diameters >20 mm. Results: In the PLBS and the first FSS, 1362 and 1382 cases with thyroid nodules sized ≥5.1 mm in diameter were found, respectively. The implementation rates of FNAC in the PLBS were 20.1%, 63.2%, and 87.7% of subjects with nodules sized 5.1-10.0, 10.1-20.0, and ≥20.1 mm in diameter, respectively. In the first FSS, the FNAC implementation rates were 7.3%, 26.0%, and 50.0% in the subjects with nodules with diameters 5.1-10.0, 10.1-20.0, and ≥20.1 mm, respectively. In the subjects who underwent FNAC, the detection rates of malignant and suspected malignant nodules were 21.4% and 34.1% in the PLBS and first FSS, respectively. In the first FSS, malignant or suspected malignant nodules were found in 0.63% and 0.40% of subjects who had nodules of diameters ≤5.0 mm and 5.1-10.0 mm in the PLBS, respectively. In contrast, in the subjects with nodules measuring ≥10.0 mm in diameter in the PLBS, no malignancies were detected. Conclusions: The use of a protocol that conformed to the Japanese guidelines led to a reduction in the FNAC implementation rate and an increase in the malignancy detection rate in smaller nodules. In addition, the use of this strategy enabled us to avoid detection failure of thyroid carcinomas >10.0 mm.

Psychosocial support for the examinees and their families during the secondary confirmatory examination:Analyses of support records at first visit.

Background and Purpose The Thyroid Ultrasound Examination (TUE) program is conducted as part of the Fukushima Health Management Survey. Following the established criteria, examinees are called in for a secondary confirmation examination, which may induce high anxiety related to a thyroid cancer for both the examinees and their families. Therefore, Fukushima Medical University created the Thyroid Support Team to reduce anxiety. The purpose of this study is to analyze the psychosocial support for examinees and their families through two types of records, and to clarify the current issues and determine future directions of support.Materials and methods We analyzed 223 records of support for the first visit of examinees who attended the secondary confirmatory examination, conducted at Fukushima Medical University from September 2018 to March 2019.Results During the first visit, frequent topics and questions brought up by the examinees and their families were about the "Thyroid Ultrasound Examination (TUE) program" and "Examination findings". The Thyroid Support Team members assisted them by "Responding to questions", "Confirming the doctor's explanation" and "Providing information". The percentage of people with high anxiety decreased in both examinees and their family members after the examination. The level of anxiety was lower among those who had already taken the secondary confirmatory examination. Family members' anxiety was significantly higher than that of the examinees, and anxiety levels were highly correlated between examinees and their families.Conclusion The psychosocial support for examinees and their families was important in reducing their anxiety.　Currently there are changes in social conditions and various opinions concerning the TUE.　Thus, careful explanation and the need for decision-making supports for the examinees and their families increased. Also, we should take into account the aging of the examinees and expanding the available psychosocial support.

The current status of 492 adult women with Turner syndrome: a questionnaire survey by the Foundation for Growth Science.

Current status and its background of Adult Turner Syndrome (TS) are not clarified well. Via a questionnaire survey of 492 adult women with TS, this study investigated the association between menstruation, Kaufmann therapy (menstrual induction therapy), social status (education, employment & marriage), complications, transition from pediatric to adult care, and sex chromosome karyotype using statistical methods. Spontaneous menarche occurred in 22.0% and more frequently among patients with the 45,X/46,XX karyotype. Over 60% of these subjects, menstruation did not persist regularly. Kauffmann therapy was performed in 69.4%; the most common formulation was a conjugated estrogen and progesterone combination. Marriage and higher education advancement rates were low in adults with TS, whereas their employment rate was similar to that of the age-matched general female population. Patients receiving Kauffmann therapy had higher complication rates, greater education length, and higher employment rates. The higher-education advancement rate was observed among patients with 45,X/46,X,Xi and 46,X,Xi karyotypes. Transition from pediatrician to adult specialist was not smooth, subjects were treated in pediatric departments (60.7%), gynecological department (21.4%), internal medicine departments (13.3%), and others. While reason is not clear, the largest number of TS patients are treated in general pediatrics and the percentage of receiving Kauffmann therapy and having complication were significantly lower than in pediatric and adult department of endocrinology (& metabolism). This Study revealed many novel findings of adult TS.

Position paper from the Japan Thyroid Association task force on the management of low-risk papillary thyroid microcarcinoma (T1aN0M0) in adults.

The incidence of thyroid carcinoma has been increasing worldwide. This is interpreted as an increase in the incidental detection of papillary thyroid microcarcinomas (PTMCs). However, mortality has not changed, suggesting overdiagnosis and overtreatment. Prospective clinical trials of active surveillance for low-risk PTMC (T1aN0M0) have been conducted in two Japanese institutions since the 1990s. Based on the favorable outcomes of these trials, active surveillance has been gradually adopted worldwide. A task force on the management of PTMC in adults organized by the Japan Thyroid Association therefore conducted a systematic review and has produced the present position paper based on the scientific evidence concerning active surveillance. This paper indicates evidence for the increased incidence of PTMC, favorable surgical outcomes for low-risk PTMC, recommended criteria for diagnosis using fine needle aspiration cytology, and evaluation of lymph node metastasis (LNM), extrathyroidal extension (ETE) and distant metastasis. Active surveillance has also been reported with a low incidence of disease progression and no subsequent recurrence or adverse events on survival if conversion surgery was performed at a slightly advanced stage. Active surveillance is a safe and valid strategy for PTMC, because it might preserve physical quality of life and reduce 10-year medical costs. However, some points should be noted when performing active surveillance. Immediate surgery is needed for PTMC showing high-risk features, such as clinical LNM, ETE or distant metastasis. Active surveillance should be performed under an appropriate medical team and should be continued for life.

Cytological examination of the thyroid in children and adolescents after the Fukushima Nuclear Power Plant accident: the Fukushima Health Management Survey.

The Fukushima Daiichi Nuclear Power Plant accident occurred on March 11 2011, following the Great East Japan Earthquake and tsunami. Radioactive materials, including I-131, were released into the environment after the accident. Shortly after, the prefectural government initiated the Fukushima Health Management Survey for monitoring the long-term health conditions of the residents of Fukushima Prefecture. In the survey, thyroid ultrasonography was scheduled for all people aged 18 years or younger who were living in Fukushima Prefecture at the time of disaster. The total number of examinees was approximately 370,000 in the Preliminary Baseline Survey (PBLS), and 380,000 in the first Full-scale Survey (FSS). First, thyroid ultrasonography was performed as the Primary Examination. When a thyroid nodule that meets the fine needle aspiration cytology (FNAC) guideline is detected, thyroid FNAC is performed. By the end of June 2017, the cytological specimens of 187 examinees had been interpreted as Malignant or Suspicious for Malignancy (SFM). In this article, the cytological results of whole categories are presented using the criteria of The Bethesda System for Reporting Thyroid Cytopathology. The total numbers of examinees with SFM or Malignant in PBLS and at the first FSS were 106 (62.0%) and 71 (38.0%), respectively. The data of the cytological results of SFM and Malignant were already reported. However, this is the first report of cytological data from categories other than SFM and Malignant. The results of the current study will contribute to future research into the thyroid conditions of children and adolescents.

Nested matched case control study for the Japan Fukushima Health Management Survey's first full-scale (second-round) thyroid examination.

Since Fukushima nuclear accident in 2011, thyroid ultrasound examinations have been conducted. The first full-scale examination detected 71 thyroid-cancer cases. This study examined whether radiation exposure was associated with thyroid-cancer incidence.Subjects were participants in the baseline screening and newborns during the 2011 fiscal year. Under nested matched case-control study design, 10 controls per each case were selected by matching the age, sex, baseline screening results, and interval between examinations. With 3 dose levels of external radiation: 1.3 + mSv (upper), 0.8 to 1.3 (middle), and 0.0 to 0.8 (reference), we applied 2 logistic models adjusting for 3 participation-proportions (primary, secondary, and fine-needle aspiratory cytology), overweight, and the B-result of baseline screening (Model 1), and past medical history, family history of thyroid cancer, and frequencies of eating seafood and seaweed in addition to the parameters in Model 1 (Model 2). We examined each model in 3 ways: (a) excluding subjects with a missing radiation exposure dose; and substituting (b1) median or (b2) mean dose of the municipality with missing dose.Odds ratios (ORs) of middle-dose exposure were (a) 1.35 (0.46-3.94), (b1) 1.55 (0.61-3.96), and (b2) 1.23 (0.50-3.03) for Model 1, and (a) 1.18 (0.39-3.57), (b1) 1.31 (0.49-3.49), and (b2) 1.02 (0.40-2.59) for Model 2. For upper-dose exposure, similar results were obtained. Past medical history was significantly associated (odds ratio  = 2.04-2.08) with both (b1) and (b2) in Model 2.No significant associations were obtained between the external radiation exposure and thyroid-cancer incidence.

A nationwide questionnaire survey targeting Japanese pediatric endocrinologists regarding transitional care in childhood, adolescent, and young adult cancer survivors.

Existing guidelines recommend long-term follow-up of childhood cancer survivors (CCS). However, in Japan, transitional care for CCS has not been established. To ascertain the current status in Japan, and to cultivate a better understanding, a questionnaire survey was conducted on transitional care in CCS, and adolescent and young adult (AYA) cancer survivors. Questionnaires were distributed to 183 councilors (137 institutions) of the Japanese Society for Pediatric Endocrinology. A total of 131 responses, representative of 174 councilors, were obtained. The response rate was 95%. Among the respondents, 91% had experience in medical care for cancer patients, while 63% had experience in transitional care; however, the number of patients referred to adult clinics was small. Further, 89% acknowledged the availability of adult endocrinologists who were willing to accept these patients; although their numbers were insufficient. Pediatric endocrinologists highlighted difficulties in medical examinations concerning infertility, obesity, pregnancy/delivery, and gonadal dysfunction, in that order. Staff and time shortages were listed as some of the challenges faced by medical staff, while multisystem morbidity was listed for patients. This nationwide questionnaire survey revealed that Japanese pediatric endocrinologists require cooperation between related departments and collaborative infrastructure to develop transitional care for cancer survivors.

Absorbed radiation doses in the thyroid as estimated by UNSCEAR and subsequent risk of childhood thyroid cancer following the Great East Japan Earthquake.

The identification of thyroid cancers among children after the Chernobyl nuclear power plant accident propelled concerns regarding long-term radiation effects on thyroid cancer in children affected by the Fukushima Daiichi nuclear power plant accident in Fukushima, Japan. Herein we consider the potential association between absorbed dose in the thyroid and the risk of developing thyroid cancer as detected by ultrasonography on 300 473 children and adolescents aged 0-18 years in Fukushima. The absorbed dose mentioned in the present study indicates the sum of that from external exposure and that from internally deposited radionuclides. We grouped participants according to estimated absorbed doses in each of 59 municipalities in Fukushima Prefecture, based on The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2013 report. The 59 municipalities were assigned to quartiles by dose. We limited our analyses to participants aged ≥6 years because only one case of thyroid cancer was observed in participants aged ≤5 years; 164 299 participants were included in the final analysis. Compared with the lowest dose quartile, the age- and sex-adjusted rate ratios (95% confidence intervals) for the low-middle, high-middle and highest quartiles were 2.00 (0.84-4.80), 1.34 (0.50-3.59) and 1.42 (0.55-3.67) for the 6-14-year-old groups and 1.99 (0.70-5.70), 0.54 (0.13-2.31) and 0.51 (0.12-2.15) for the >15-year-old group, respectively. No dose-dependent pattern emerged from the geographical distribution of absorbed doses by municipality, as estimated by UNSCEAR, and the detection of thyroid cancer among participants within 4-6 years after the accident. Ongoing surveillance might further clarify the effects of low-dose radiation exposure on thyroid cancer in Fukushima.

Investigation of thyroid cancer cases that were not detected in the Thyroid Ultrasound Examination program of the Fukushima Health Management Survey but diagnosed at Fukushima Medical University Hospital.

The Great East Japan Earthquake, which occurred on March 11, 2011, and its subsequent Fukushima Daiichi Nuclear Power Plant accident, prompted implementation of the Thyroid Ultrasound Examination (TUE) program as a part of the Fukushima Health Management Survey. The purpose of this program is to support residents of Fukushima Prefecture, and to analyze the health effects of the released radionuclides. Regardless of relatively high participation rates and a well-planned diagnostic flow, it is conceivable that not all thyroid cancer cases can be detected by the TUE program. The aims of the present study were to identify and characterize these "outside" cases, targeting patients at Fukushima Medical University (FMU) Hospital. As of June 30, 2017, we have successfully identified 11 outside cases. These corresponded to 5.7% of the 194 subjects who were identified as having thyroid cancer or suspected thyroid cancer in the TUE program. Although the outside subjects of other institutes were not investigated, the present study may have identified the majority of outside subjects in Japan, considering that FMU Hospital treats a large number of thyroid cancer subjects. Furthermore, the characteristics of the 11 subjects were not different from those of the subjects identified in the TUE program. These findings confirm that the TUE program was able to identify subjects of thyroid cancer adequately and sufficiently.

External Radiation Dose, Obesity, and Risk of Childhood Thyroid Cancer After the Fukushima Daiichi Nuclear Power Plant Accident: The Fukushima Health Management Survey.

BACKGROUND: The 2011 Great East Japan Earthquake led to a nuclear accident at Fukushima Daiichi Nuclear Power Plant. This study examines the associations of radiation dose and lifestyle factors with incidence of thyroid cancer in Fukushima. METHODS: We designed a prospective study with 300,473 participants aged 18 years or younger, who underwent thyroid examinations from October 2011. Follow-up surveys were conducted through June 2017, and 245,530 participants (123,480 men and 122,050 women, 82% follow-up) received follow-up examinations. Fukushima Prefecture was divided into five areas based on individual external radiation dose. We calculated relative risks and 95% confidence intervals (CIs) for thyroid cancer in each area, with area of lowest dose as reference, using age-adjusted Poisson regression models. We also calculated risks associated with overweight and obesity. RESULTS: The incidence per 100,000 for Groups A (highest dose), B, C, D, and E (lowest dose) were 13.5, 19.2, 17.3, 9.0, and 8.3, respectively. Compared with Group E, the age-adjusted risks (95% CIs) were 1.62 (0.59, 4.47) for group A, 2.32 (0.86, 6.24) for group B, 2.21 (0.82, 5.94) for group C, and 1.02 (0.36, 2.86) for group D. Obesity was positively associated with thyroid cancer incidence; the multivariable-adjusted risk of thyroid cancer was 2.23 (1.01, 4.90) for obese individuals compared with nonobese individuals. CONCLUSION: Regional differences in radiation dose were not associated with increased risk of thyroid cancer among children in Fukushima within 4 to 6 years after the nuclear power plant accident. Obesity may be an important factor for further follow-up in Fukushima.

Incidence of Thyroid Cancer Among Children and Young Adults in Fukushima, Japan, Screened With 2 Rounds of Ultrasonography Within 5 Years of the 2011 Fukushima Daiichi Nuclear Power Station Accident.

Importance: Ultrasonographic (US) screening for thyroid cancer was performed in the Fukushima Health Management Survey after the 2011 Fukushima Daiichi nuclear power station accident. Clinical characteristics of thyroid cancers screened by US among children and young adults during the first 5 years after the accident were analyzed. Objectives: To evaluate the number of detected thyroid cancers by age group within 5 years of the Fukushima Daiichi nuclear power station accident and to compare the basic clinical characteristics and demographic patterns in first- and second-round examinations. Design, Setting, and Participants: In this observational study, 324 301 individuals 18 years or younger at the time of accident were included. Patients received a cytologic diagnosis of malignant or suspected malignant thyroid cancer during the first (fiscal years 2011-2013) or second round (fiscal years 2014-2015) of screening. Number of detected cases of cancer was evaluated, correcting for the number of examinees by age group at the time of the accident and for the incidence of detected cancers according to age group at the time of the screening (age groups were divided into 3-year intervals). Results were compared using the age-specific incidence of unscreened cancers from a national cancer registry. Main Outcomes and Measures: Clinical baseline characteristics of the patients and the age-specific number and incidence of thyroid cancers detected during the second round. Results: Among 299 905 individuals screened in the first round (50.5% male; mean [SD] age at screening, 14.9 [2.6] years), malignant or suspected thyroid cancer was diagnosed in 116. Among 271 083 individuals screened in the second round (50.4% male; age at screening, 12.6 [3.2] years), malignant or suspected thyroid cancer was diagnosed in 71. The most common pathologic diagnosis in surgical cases was papillary thyroid cancer (149 of 152 [98.0%]). The distribution pattern by age group at the time of the accident, where the number of detected thyroid cancer cases was corrected by the number of examinees, increased with older age in both screening rounds. This demographic pattern was similar between the first and second examinations. The distribution pattern of the incidence rate by age group at the time of screening in the second round also increased with older age. The incidence rate detected by screening was 29 cases per 100 000 person-years for those aged 15 to 17 years, 48 cases per 100 000 person-years for those aged 18 to 20 years, and 64 cases per 100 000 person-years for those aged 21 to 22 years. Conclusions and Relevance: Large-scale mass US screening of young people resulted in the diagnosis of a number of thyroid cancers, with no major changes in overall characteristics within 5 years of the 2011 Fukushima nuclear power station accident. These results suggest that US screening can identify many detectable cancers from a large pool of nonclinical and subclinical thyroid cancers among individuals of a relatively young age, in an age-dependent manner.