Radiation dose-response relationships for thyroid nodules and autoimmune thyroid diseases in Hiroshima and Nagasaki atomic bomb survivors 55-58 years after radiation exposure

Radiation Implication in Pediatric Second Primary Thyroid Malignancy (SPTM) Cumulative Incidence and Mortality in the United States: Large Cohort Evidence

OBJECTIVE

To assess racial and sex variances in second primary thyroid malignancy (SPTM) cumulative incidence and temporal trends and the radiation exposure effect in pediatric SPTM.

MATERIALS AND METHODS

A retrospective cohort study, a non-experimental epidemiologic design, was used to assess the cumulative incidence (CmI) and temporal trends as well as the exposure effect of radiation in SPTM among children, 0-19 years, in the Surveillance, Epidemiology, and End Results (SEER) registry, National Cancer Institute (NCI), USA. Percent change (PC) and annual percent change (APC) were used to examine CmI rates and temporal trends, while chi-square statistics and binomial regression models were used to examine variable distribution by race and to determine the exposure effect of radiation on SPTM as well as mortality, respectively.

RESULTS

The frequency of pediatric thyroid cancer was (n = 3457) between 1973 and 2013/14, while the PC was 151.2 for all races but 99.8 among whites. Of all pediatric thyroid cancers diagnosed during this period, SPTM accounted for 3% (n = 99). Compared to whites, blacks/AA were 60% less likely to present with SPTM, adjusted risk ratio, aRR = 0.40, 99% CI 0.06-2.47, while other races were 18% more likely to develop SPTM, aRR = 1.18, 99% CI 0.48-2.87. Additionally, females relative to males were 63% less likely to be diagnosed with SPTM, aRR = 0.37, 99% CI 0.22-0.61. With respect to urbanicity, compared to children in rural areas, those in urban areas were 21% less likely to develop SPTM, aRR = 0.79, 99% CI, 0.12-5.35, while children in metropolitan areas were 40% less likely to develop SPTM, aRR = 0.60, 99% CI, 0.10-3.59. Although imprecise, there was a 5% increased risk of SPTM, with radiation as an exposure effect, aRR = 1.05, 99% CI 1.01-1.75.

CONCLUSIONS

There are increasing temporal trends in pediatric SPTM with blacks relative to whites having observed lower incidence, despite an increasing percent change among blacks/AA, indicative of the disproportionate burden of this malignant neoplasm. SPTM risk was higher among males and in rural areas, while radiation as a risk for SPTM was clinically and biologically meaningful, albeit an observed statistically insignificant inference due to sampling variability, requiring intervention mapping in radiation exposure margination among children.

Secondary cancer risk assessments following the proton therapy of lung cancer as the functions of field characteristics and patient age

INTRODUCTION

Radiation-induced secondary cancers relevant to proton therapy are still a main concern among cancer survivors. This study aims to determine the effects of age at exposure and treatment field size on radiation-induced secondary tumors following the proton therapy of lung cancer within out of field organs through the Monte Carlo (MC) simulation approach.

MATERIAL AND METHODS

A full MC model of ICRP-110 male phantom was simulated to calculate the absorbed dose corresponding to secondary radiations within distant organs from the tumor volume. Then, the risks of secondary malignancies were estimated by employing the recommended risk model by the Committee of Biological Effects of Ionizing Radiation (BEIR) for different treatment field sizes and various patient ages at exposure.

RESULTS

The results revealed that by increasing the patient age from 25 to 45 years, lifetime attributable risk (LAR) values were decreased. Maximum and minimum mortality rates were obtained for the liver and thyroid at the fixed age of 25 years, respectively. Calculated risk values for most near organs to the tumor were higher than those for distant organs. Changing the aperture size from 5 × 5 cm2 to 8 × 10 cm2 resulted in LAR increments with maximum variations of 12.5% for the stomach and a rough variation of 1.12 times in LAR for all exposure ages.

CONCLUSION

Our work on whole-body phantom addresses the impact of age at exposure and aperture size on LAR during the proton therapy of lung cancer. To minimize secondary cancer risks relevant to proton therapy of lung cancer, extra attention should be considered.

Sensitivity to thyroid hormone indices are associated with papillary thyroid carcinoma in Chinese patients with thyroid nodules

BACKGROUND

The association between thyroid hormone sensitivity and thyroid cancer is unknown, and we aimed to investigate the association between sensitivity to thyroid hormone indices and papillary thyroid carcinoma (PTC) in Chinese patients with thyroid nodules (TNs).

METHODS

A total of 1,998 patients undergoing thyroid surgery due to TNs from Nanjing Drum Tower Hospital were included in this study. We evaluated central sensitivity to thyroid hormones, such as thyroid stimulating hormone index (TSHI), TSH T4 resistance index (TT4RI), thyroid feedback quantile-based index (TFQI), and parametric thyroid feedback quantile-based Index (PTFQI). Peripheral sensitivity to thyroid hormone was evaluated by FT3 to FT4 ratio. Multivariate logistic regression analysis was performed to evaluate the association between sensitivity to thyroid hormone indices and PTC risk.

RESULTS

The results showed that central indices of thyroid hormone sensitivity, including TSHI, TT4RI, TFQI, and PTFQI, were positively associated with PTC risk. For each SD increase in TSHI, TT4RI, TFQI, and PTFQI, the odds ratios (OR, 95% CI) of PTC were 1.31 (1.18-1.46), 1.01 (1.01-1.02), 1.94 (1.45-2.60), and 1.82 (1.41-2.34), respectively. On the other hand, the association between peripheral sensitivity to thyroid hormone and PTC was significantly negative. For each SD increase in FT3/FT4 ratio, the OR (95% CI) of PTC was 0.18 (0.03-0.96), and a negative correlation was found between FT3/FT4 ratio and TNM staging of PTC.

CONCLUSIONS

Sensitivity to thyroid hormone indices could be used as new indicators for predicting PTC in Chinese patients with TNs. Future researches are still needed to confirm our findings.

Selenium and thyroid diseases

Selenium, a non-metallic element, is a micronutrient essential for the biosynthesis of selenoproteins containing selenocysteine. In adults, the thyroid contains the highest amount of selenium per gram of tissue. Most known selenoproteins, such as glutathione peroxidase, are expressed in the thyroid and are involved in thyroid hormone metabolism, redox state regulation, and maintenance of cellular homeostasis. Some clinical studies have shown that lack of selenium will increase the prevalence of several kinds of thyroid diseases. Selenium treatment in patients with Graves' orbitopathy has been shown to delay disease progression and improve the quality of life. Selenium supplementation in Hashimoto's thyroiditis was associated with the decreased levels of anti-thyroid peroxidase antibody and improved thyroid ultrasound structure. In thyroid cancer, various selenium supplements have shown variable anticancer activity. However, published results remain the conflicting and more clinical evidence is still needed to determine the clinical significance of selenium. This article reviews the strong association between selenium and thyroid disease and provides new ideas for the clinical management of selenium in thyroid disease.

The effect of exposure on cattle thyroid after the Fukushima Daiichi nuclear power plant accident

Nuclear plant accidents can be a risk for thyroid cancer due to iodine radioisotopes. Near the Fukushima Daiichi nuclear power plant, cattle were exposed to radiation after the accident occurred in May 2011. Here we estimated the total radiation exposure to cattle thyroid and its effects on thyroid function. Until October 2016, the estimated external exposure dose in Farm A was 1416 mGy, while internal exposure dose of ¹³¹I, ¹³⁴Cs, and ¹³⁷Cs were 85, 8.8, and 9.7 mGy in Farm A and 34, 0.2, and 0.3 mGy in Farm B, respectively. The exposed cattle had thyroid with relatively lower weight and lower level of stable iodine, which did not exhibit any pathological findings. Compared with the control, the plasma level of thyroid-stimulating hormone (TSH) was higher in Farm A cattle born before the accident, while the plasma thyroxine (T4) was higher in Farm A cattle born after the accident, suggesting that exposed cattle showed slight hyperactivation of the thyroid gland. In addition, Farm A cattle have higher level of cortisol, one of the anterior pituitary gland-derived hormones. However, we did not observe a causal relationship between the radiation exposure and cattle thyroid.

The association between serum concentration of thyroid hormones and thyroid cancer: a cohort study

The impact of serum thyroid hormone levels on thyroid cancer risk is unclear. Some studies reported that elevated thyroid-stimulating hormone (TSH) is associated with higher risk for incidence of thyroid cancer, but other studies reported no relationship. We conducted a large cohort study in 164,596 South Korean men and women who were free of thyroid cancer at baseline and underwent health examination with hormone levels of thyroid function. A parametric proportional hazard model was used to evaluate the adjusted hazard ratio (HR) and 95% CI. During 2,277,749.78 person-years of follow-up, 1280 incident thyroid cancers were identified (men = 593, women = 687). Among men, the multivariable-adjusted HR (95% CI) for thyroid cancer comparing low levels of TSH with normal levels of TSH was 2.95 (1.67-5.23), whereas the corresponding HR (95% CI) in women was 1.5 (0.88-2.55). High levels of free T4 and free T3 were also associated with incident thyroid cancer in both men and women. In clinical implication, overt hyperthyroidism is associated with thyroid cancer in both men and women. Within the euthyroid range, the highest tertile of TSH was associated with a lower risk of thyroid cancer than the lowest TSH tertile and the highest FT4 tertile was associated with a higher risk of thyroid cancer than the lowest FT4 tertile in both men and women. Our finding indicates that low levels of TSH and high levels of FT4, even within the normal range, were associated with an increased risk of incident thyroid cancer.

Evaluation of a new acrylic-lead shielding device for peripheral dose reduction during cone-beam computed tomography

Objective

To clarify the peripheral dose changes, especially in the eye lens and thyroid gland regions, using an acrylic-lead shield in cone-beam computed tomography (CBCT).

Methods

The acrylic-lead shield consists of system walls and a system mat. The radiophotoluminescence glass dosemeter was set on the eye lens and thyroid gland regions on the RANDO phantom. The system mat was laid under the RANDO phantom ranging from the top of the head to the shoulders, and then, the system walls shielded the phantom's head. Additionally, the phantom was covered anteriorly with a band that had the same shielding ability as the system mat to cover the thyroid gland region. Protocols for CBCT imaging of the thoracic or pelvic region in clinical practice were used. The measurement was performed with and without the acrylic-lead shield.

Results

The dose to the eye lens region was reduced by 45% using the system wall. Conversely, the dose to the thyroid gland was unchanged. The use of the system mat reduced the dose to the thyroid gland region by 47%, and the dose to the eye lens was reduced by 22%. The dose to the eye lens region decreased to the background level using the system walls and mat.

Conclusion

The newly proposed device using an acrylic-lead shield reduced the peripheral dose in CBCT imaging.

Advances in knowledge

Attention is focused on managing peripheral dose in image-guided radiation therapy. The peripheral dose reduction using the acrylic-lead shield is a new proposal in radiotherapy that has never been studied.

Incidence of Diabetes in the Atomic Bomb Survivors: 1969-2015

CONTEXT

Recent epidemiological studies have shown increased risk of diabetes among childhood cancer survivors who received high therapeutic doses of radiation, particularly to the total body or to the abdomen. However, the effect of low-to-moderate dose radiation (<4 Gy) on the risk of diabetes is still unknown.

OBJECTIVES

To investigate the radiation effect on diabetes incidence among atomic bomb (A-bomb) survivors, and whether the dose response is modified by other factors including city, sex, and age at time of bombing (ATB).

METHODS

9131 participants without diabetes at baseline were observed through biennial clinical exams from 1969 to 2015. A Cox proportional hazards model was used to estimate hazard ratios (HR) to evaluate the dose response for diabetes incidence.

RESULTS

During the study period, 1417 incident diabetes cases were identified. The overall crude incidence rate was 7.01/103 person-years. Radiation dose was significantly associated with diabetes incidence, with effect modification by city and age ATB. In Hiroshima, at ages 10 and 30 ATB, the HRs at 1 Gy of pancreatic radiation dose were 1.47 (95% CI, 1.31-1.66) and 1.13 (95% CI, 0.97-1.31), respectively. However, no significant radiation dose response was observed at these ages in Nagasaki. The HR for radiation dose was higher among those who were younger ATB and decreased 1% for each additional year of age.

CONCLUSIONS

Among A-bomb survivors, a radiation association was suggested for incidence of diabetes. Results were inconsistent by city and age ATB, which could indicate potential confounding of the radiation association with diabetes.

Environmental pollution, a hidden culprit for health issues

The environmental and health impacts from the massive discharge of chemicals and subsequent pollution have been gaining increasing public concern. The unintended exposure to different pollutants, such as heavy metals, air pollutants and organic chemicals, may cause diverse deleterious effects on human bodies, resulting in the incidence and progression of different diseases. The article reviewed the outbreak of environmental pollution-related public health emergencies, the epidemiological evidence on certain pollution-correlated health effects, and the pathological studies on specific pollutant exposure. By recalling the notable historical life-threatening disasters incurred by local chemical pollution, the damning evidence was presented to criminate certain pollutants as the main culprit for the given health issues. The epidemiological data on the prevalence of some common diseases revealed a variety of environmental pollutants to blame, such as endocrine-disrupting chemicals (EDCs), fine particulate matters (PMs) and heavy metals. The retrospection of toxicological studies provided illustrative clues for evaluating ambient pollutant-induced health risks. Overall, environmental pollution, as the hidden culprit, should answer for the increasing public health burden, and more efforts are highly encouraged to strive to explore the cause-and-effect relationships through extensive epidemiological and pathological studies.

The Iodine Rush: Over- or Under-Iodination Risk in the Prophylactic Use of Iodine for Thyroid Blocking in the Event of a Nuclear Disaster

Iodine is an essential element for the production of thyroid hormones (THs). Both deficient and excess iodine intakes may precipitate in adverse thyroidal events. Radioactive iodine (RI) is a common byproduct of nuclear fission processes. During nuclear emergencies RI may be released in a plume, or cloud, contaminating the environment. If inhaled or ingested, it may lead to internal radiation exposure and the uptake of RI mainly by the thyroid gland that absorbs stable iodine (SI) and RI in the same way. A dose of radiation delivered to the thyroid gland is a main risk factor for the thyroid cancer development. The SI prophylaxis helps prevent childhood thyroid cancer. The thyroid gland saturation with prophylactic SI ingestion, reduces the internal exposure of the thyroid by blocking the uptake of RI and inhibiting iodide organification. However, negative impact of inadequate SI intake must be considered. We provide an overview on the recommended iodine intake and the impact of SI and RI on thyroid in children and adolescents, discussing the benefits and adverse effects of the prophylactic SI for thyroid blocking during a nuclear accident. The use of SI for protection against RI may be recommended in cases of radiological or nuclear emergencies, moreover the administration of iodine for prophylactic purposes should be cautious. Benefits and risks should also be considered according to age. Adverse effects from iodine administration cannot be excluded. Precise indications are mandatory to use the iodine for thyroid blocking. Due to this natural adaption mechanism it's possible to tolerate large doses of iodine without clinical effects, however, a prolonged assumption of the iodine when not needed can be dangerous and may precipitate in severe thyroidal and non-thyroidal negative effects.

Risk of thyroid disorders in adult and childhood Hodgkin lymphoma survivors 40 years after treatment

Thyroid abnormalities are well reported following childhood treatment for Hodgkin Lymphoma (HL). Limited information exists for adult patients and after modern treatments. We analyzed risks of thyroid disorders in 237 female participants treated at the Royal Marsden Hospital 1970-2015. Multivariable analyses of risk according to treatment and time-related factors, survival analyses, and Cox regression modeling were undertaken. Overall, 33.8% of patients reported thyroid disorders (hypothyroidism 30.0% and thyroid nodules 6.8%). Cumulative prevalence was 42.9% by 40 years follow-up. Risks were greatest after supradiaphragmatic radiotherapy (RR = 5.0, p < 0.001), and increasing dose (RR = 1.03/Gy, p < 0.001). There was no association with a chemotherapy agent. Risks of thyroid disease were as raised following adult as childhood treatment. There was no trend in risk by decade of supradiaphragmatic radiotherapy treatment. Risks of thyroid disease after supradiaphragmatic radiotherapy are as great after adult as childhood treatment and persist after more recent treatment periods.

Immunohistochemical Analysis of Toll-Like Receptors, MyD88, and TRIF in Human Papillary Thyroid Carcinoma and Anaplastic Thyroid Carcinoma

Purpose

We hypothesized that innate immune response pathways might be involved in thyroid carcinogenesis. To investigate this hypothesis, we aimed at analyzing the expression of several receptors and molecules in the innate immune system in papillary thyroid carcinoma (PTC) and anaplastic thyroid carcinoma (ATC) tissues.

Methods

Of the surgically resected specimens, 11 ATC tissues, 25 PTC tissues, and 8 nodular hyperplasia (NH) tissues were selected and examined for the expression of toll-like receptor (TLR) 2, TLR3, TLR4, TLR5, TLR7, TLR9, the myeloid differentiation primary response gene 88 (MyD88), and toll-interleukin-1 receptor domain-containing adaptor inducing INF-β (TRIF) by immunohistochemistry (IHC).

Results

Several TLRs were expressed in each tissue. TLR3 was strongly expressed in all tissues. In contrast, TLR4 was not detected in any tissues. While TLR5 was moderately expressed in NH but significantly reduced in PTC and ATC, TLR9 was absent in NH tissue but moderately expressed in both PTC and ATC. On MyD88 expression, no significant difference was found between PTC and ATC. TRIF was significantly upregulated in PTC and ATC compared to NH. Surprisingly, PTC and ATC tissues exhibited similar expression patterns of TLRs, MyD88, and TRIF.

Conclusion

These data suggest the involvement of the innate immune system in both PTC and ATC. Specifically, TLR3-mediated TRIF activation was confirmed in PTC and ATC. This provides new insight into thyroid carcinogenesis.

The Effect of ThyroidߚStimulating Hormone on Stage of Differentiated Thyroid Carcinoma

Introduction

Thyroid cancer is the most common endocrine malignancy, and it has the fastest increase rate in incidence in both sexes, with a yearly increase of 3% over the last decade. Thyroid‐stimulating hormone (TSH) is the main driver for the thyroid gland to produce thyroid hormone. The main purpose of this study was to assess the relationship between serum TSH level and the stage of malignancy in patients with differentiated thyroid cancer.

Methods

This cross‐sectional study was performed on 77 patients with thyroid cancer. The demographic characteristics, TSH level and stage of malignancy were recorded for all patients in the data collection form. The data analysis was conducted by descriptive statistics using SPSS 20.0 software.

Results

The results show a significant relationship (p‐value = .025) between the malignancy stage and serum TSH level. The mean TSH level in patients of stage 3 (5.70 ± 2.03) was significantly higher than patients in stage 2 (2.58 ± 0.52) and stage 1 (2.33 ± 0.28). No significant relationship was observed between the age of patients and serum TSH level. Although the mean serum TSH level in men (3.61 ± 0.98) was higher than in women (2.52 ± 0.25), the difference was not statistically significant.

Conclusions

According to the results of this study, serum TSH level can be considered as a predictor of the stage of differentiated thyroid cancer. Therefore, it can be used to predict the likelihood of cancer and improve the outcome and extent of thyroidectomy in patients with thyroid cancer.

Thyroid‐stimulating hormone (TSH) is the main driver for the thyroid gland to produce thyroid hormone. The main purpose of this study is to assess the relationship between serum TSH level and the stage of malignancy in patients with differentiated thyroid cancer.

Trends in Childhood Thyroid Cancer incidence in Korea and Its Potential Risk Factors

BACKGROUND

Although the incidence of thyroid cancer had been increasing until a few years ago, a decrease has been observed in the last years, probably due to the reduction of the screening tests in Korea. Childhood thyroid cancer has been increasing in the past with the same trend as in adults, but there have been few reports on recent trends. We analyzed the trends of thyroid cancer in Korean children and related factors.

METHODS

From national statistics and cancer register database, the data of age-specific incidence rate in Korean childhood thyroid cancer from 1999 to 2017 was obtained, and levels of seaweed intake, the number of computed tomography (CT) and neck ultrasonography (US), obesity prevalence rate, and smoking and alcohol consumption rates in children were analyzed.

RESULTS

The age-specific incidence of thyroid cancer in Korean children has increased in both genders between 1999 and 2017 (2.0 in 1999 vs. 7.2 in 2017, per population of 100,000), especially in the age group of 14-18 years (1.5 in 1999 vs. 5.5 in 2017, per population of 100,000). During the same period, levels of seaweed intake, number of CT scans and neck US, and prevalence of obesity in children increased significantly, while childhood smoking and alcohol consumption rates decreased.

CONCLUSION

Unlike the adult thyroid cancer in Korea, childhood thyroid cancer continues to increase, and the cause might be accompanied by actual increases due to the environmental factors such as excessive iodine intake, exposure to medical radiation, and increased obesity prevalence as well as the screening effect.

Individual response of humans to ionising radiation: governing factors and importance for radiological protection

Tissue reactions and stochastic effects after exposure to ionising radiation are variable between individuals but the factors and mechanisms governing individual responses are not well understood. Individual responses can be measured at different levels of biological organization and using different endpoints following varying doses of radiation, including: cancers, non-cancer diseases and mortality in the whole organism; normal tissue reactions after exposures; and, cellular endpoints such as chromosomal damage and molecular alterations. There is no doubt that many factors influence the responses of people to radiation to different degrees. In addition to the obvious general factors of radiation quality, dose, dose rate and the tissue (sub)volume irradiated, recognized and potential determining factors include age, sex, life style (e.g., smoking, diet, possibly body mass index), environmental factors, genetics and epigenetics, stochastic distribution of cellular events, and systemic comorbidities such as diabetes or viral infections. Genetic factors are commonly thought to be a substantial contributor to individual response to radiation. Apart from a small number of rare monogenic diseases such as ataxia telangiectasia, the inheritance of an abnormally responsive phenotype among a population of healthy individuals does not follow a classical Mendelian inheritance pattern. Rather it is considered to be a multi-factorial, complex trait.

Association between Uranium Exposure and Thyroid Health: A National Health and Nutrition Examination Survey Analysis and Ecological Study

Besides specific, incidental radiation exposure, which has been associated with increased thyroid cancer risk, the effects of exposure to background radiation from uranium, a naturally occurring, radioactive, and ubiquitous element, on the thyroid gland has not been widely studied. We therefore investigated the association between uranium exposure and thyroid health in the US. Using the National Health and Nutrition Examination Survey (NHANES), we assessed the association between urinary uranium levels and thyroid-related antibodies, including thyroglobulin antibodies (TgAb) and anti-thyroid peroxidase (anti-TPO), in the general population. Secondly, we performed an ecological study of age-adjusted thyroid cancer incidence rates per state and sources of uranium exposure. We included 3125 eligible participants from the NHANES and found a significant association between increased TgAb and increased urinary uranium levels when analyzed as quartiles (p = 0.0105), while no association was found with anti-TPO. In addition, although no significant correlation was found in the ecological study, certain states had high age-adjusted thyroid cancer incidence rates and a high number of uranium activity locations and high uranium concentrations in water. The present study suggests that uranium exposure may affect thyroid health, which warrants increased sampling of soil and water in high-risk states.

Thyroid nodule prevalence among women in areas of high natural background radiation, Karunagappally, Kerala, India

PURPOSE

Radiation exposure has been reported to cause thyroid nodules. The study area was Karunagapally, which has several areas with high natural radiation levels derived from thorium and its decay products. Since thyroid abnormalities are more common in women, the focus was only on women.

METHODS

The examinations included interview, ultrasonography of the thyroid and serum assays of free thyroxine (FT4), thyrotropin (TSH), and anti-thyroglobulin levels. Cumulative dose during the childhood and lifetime cumulative dose (lagged by 5 years) were estimated.

RESULTS

We examined 524 female residents aged 17-73 years and found 75 cases of solitary solid thyroid nodules. The prevalence of thyroid nodules were 14.1 % (n = 42) in high dose panchayats and 14.5% (n = 33) in low-dose panchayats. In the logistic regression analysis adjusted for age, the prevalence of solitary thyroid nodule was not linearly related to childhood cumulative dose (P for trend = 0.159) and lifetime cumulative dose (P for trend = 0.333). The prevalence of thyroiditis and hypothyroidism was not related to natural radiation exposure. Serum levels of FT4 or TSH were not related to natural radiation exposure.

CONCLUSIONS

The results obtained from the present study do not support the increase of solitary thyroid nodule, thyroiditis or hypothyroidism in relation to high-natural-background-radiation exposure.

Hyperthyroidism After Radiation Therapy for Childhood Cancer: A Report from the Childhood Cancer Survivor Study

PURPOSE

The association of hyperthyroidism with exposure to ionizing radiation is poorly understood. This study addresses the risk of hyperthyroidism in relation to incidental therapeutic radiation dose to the thyroid and pituitary glands in a large cohort of survivors of childhood cancer.

METHODS AND MATERIALS

Using the Childhood Cancer Survivor Study's cohort of 5-year survivors of childhood cancer diagnosed at hospitals in the United States and Canada between 1970 and 1986, the occurrence of hyperthyroidism through 2009 was ascertained among 12,183 survivors who responded to serial questionnaires. Radiation doses to the thyroid and pituitary glands were estimated from radiation therapy records, and chemotherapy exposures were abstracted from medical records. Binary outcome regression was used to estimate prevalence odds ratios (ORs) for hyperthyroidism at 5 years from diagnosis of childhood cancer and Poisson regression to estimate incidence rate ratios (RRs) after the first 5 years.

RESULTS

Survivors reported 179 cases of hyperthyroidism, of which 148 were diagnosed 5 or more years after their cancer diagnosis. The cumulative proportion of survivors diagnosed with hyperthyroidism by 30 years after the cancer diagnosis was 2.5% (95% confidence interval [CI], 2.0%-2.9%) among those who received radiation therapy. A linear relation adequately described the thyroid radiation dose response for prevalence of self-reported hyperthyroidism 5 years after cancer diagnosis (excess OR/Gy, 0.24; 95% CI, 0.06-0.95) and incidence rate thereafter (excess RR/Gy, 0.06; 95% CI, 0.03-0.14) over the dose range of 0 to 63 Gy. Neither radiation dose to the pituitary gland nor chemotherapy was associated significantly with hyperthyroidism. Radiation-associated risk remained elevated >25 years after exposure.

CONCLUSIONS

Risk of hyperthyroidism after radiation therapy during childhood is positively associated with external radiation dose to the thyroid gland, with radiation-related excess risk persisting for >25 years. Neither radiation dose to the pituitary gland nor chemotherapy exposures were associated with hyperthyroidism among childhood cancer survivors through early adulthood.

Long-Term Endocrine and Metabolic Consequences of Cancer Treatment: A Systematic Review

The number of patients surviving ≥5 years after initial cancer diagnosis has significantly increased during the last decades due to considerable improvements in the treatment of many cancer entities. A negative consequence of this is that the emergence of long-term sequelae and endocrine disorders account for a high proportion of these. These late effects can occur decades after cancer treatment and affect up to 50% of childhood cancer survivors. Multiple predisposing factors for endocrine late effects have been identified, including radiation, sex, and age at the time of diagnosis. A systematic literature search has been conducted using the PubMed database to offer a detailed overview of the spectrum of late endocrine disorders following oncological treatment. Most data are based on late effects of treatment in former childhood cancer patients for whom specific guidelines and recommendations already exist, whereas current knowledge concerning late effects in adult-onset cancer survivors is much less clear. Endocrine sequelae of cancer therapy include functional alterations in hypothalamic-pituitary, thyroid, parathyroid, adrenal, and gonadal regulation as well as bone and metabolic complications. Surgery, radiotherapy, chemotherapy, and immunotherapy all contribute to these sequelae. Following irradiation, endocrine organs such as the thyroid are also at risk for subsequent malignancies. Although diagnosis and management of functional and neoplastic long-term consequences of cancer therapy are comparable to other causes of endocrine disorders, cancer survivors need individually structured follow-up care in specialized surveillance centers to improve care for this rapidly growing group of patients.

MTHFR gene polymorphisms in hypothyroidism and hyperthyroidism among Jordanian females

OBJECTIVE

Methylenetetrahydrofolate reductase (MTHFR) is involved in DNA methylation that is associated with autoimmune pathology. We investigated the association between MTHFR genetic polymorphisms at g.677C>T and g.1298A>C and their haplotypes, and the risk of thyroid dysfunction among Jordanian females.

SUBJECTS AND METHODS

A case-control study involving 98 hypothyroidism cases, 66 hyperthyroidism cases and 100 controls was conducted. Polymerase chain reaction/restriction fragment length polymorphism technique was performed to determine genotypes. Statistical analysis using SPSS software was performed.

RESULTS

Genetic analysis showed a significant difference in genotype frequency of g.1298A>C between cases, and controls [hypothyroidism: AA (45.9%), AC (37.8%), CC (16.3%); hyperthyroidism: AA (9.1%), AC (69.7%), CC (21.2%); controls: AA (37.8%), AC (29.6%), CC (32.7%); CChypo vs. AAhypo: 2.55, 95% CI: (1.18-5.52); OR at least on Chypo: 1.79, 95% CI: (1.07-2.99)]; CChyper vs. AAhyper: 4.01, 95% CI: (1.79-9.01); OR at least on Chyper: 0.18, 95% CI: (0.07-0.48)]. There was no significant difference in genotype frequency of g.677C>T between cases and controls [hypothyroidism: CC (50.0%), CT (32.7%), TT (17.3%); hyperthyroidism: CC (77.3%), CT (15.2%), TT (7.6%); controls: CC (55.6%), CT (32.3%), TT (12.1%)]. There was a significant difference of MTHFR haplotypes among hypothyroidism cases and controls. TA and CC had a lower hypothyroidism risk whereas; TC showed a higher risk.

CONCLUSIONS

g.1298A>C genetic polymorphism of MTHFR may modulate the risk of thyroid disease. CC, TA, and TC haplotypes affect the risk of hypothyroidism. Larger samples should be included in the future to verify the role of MTHFR polymorphisms in thyroid diseases.

Inflammatory disease and C-reactive protein in relation to therapeutic ionising radiation exposure in the US Radiologic Technologists

Chronic inflammation underlies many autoimmune diseases, including hypothyroidism, hyperthyroidism, and rheumatoid arthritis, also type-2 diabetes and osteoarthritis. Associations have been suggested of high-dose ionising radiation exposure with type-2 diabetes and elevated levels of C-reactive protein, a marker of chronic inflammation. In this analysis we used a proportional hazards model to assess effects of radiotherapy on risks of subsequent inflammatory disease morbidity in 110,368 US radiologic technologists followed from a baseline survey (1983–1989/1994–1998) through 2008. We used a linear model to assess log-transformed C-reactive protein concentration following radiotherapy in 1326 technologists. Relative risk of diabetes increased following radiotherapy (p < 0.001), and there was a borderline significant increasing trend per treatment (p = 0.092). For osteoarthritis there was increased relative risk associated with prior radiotherapy on all questionnaires (p = 0.005), and a significant increasing trend per previous treatment (p = 0.024). No consistent increases were observed for other types of inflammatory disease (hypothyroidism, hyperthyroidism, rheumatoid arthritis) associated with radiotherapy. There was a borderline significant (p = 0.059) increasing trend with dose for C-reactive protein with numbers of prior radiotherapy treatments. Our results suggest that radiotherapy is associated with subsequent increased risk of certain inflammatory conditions, which is reinforced by our finding of elevated levels of C-reactive protein.

Evolving Understanding of the Epidemiology of Thyroid Cancer

The incidence of thyroid cancer worldwide has increased significantly over the past 3 decades, due predominantly to an increase in papillary thyroid cancer. Although most of these cancers are small and localized, population-based studies have documented a significant increase in thyroid cancers of all sizes and stages, in addition to incidence-based mortality for papillary thyroid cancer. This suggests that the increasing incidence of thyroid cancer is due in large part to increasing surveillance and overdiagnosis, but that there also appears to be a true increase in new cases of thyroid cancer.

Epidemiological studies of atomic bomb radiation at the Radiation Effects Research Foundation

Epidemiological studies of people who were exposed to atomic bomb radiation and their children who were conceived after parental exposure to radiation (F₁) have investigated late health effects of atomic bomb radiation and its transgenerational effects. Those studies were initiated by the Atomic Bomb Casualty Commission (ABCC) in the 1950s. ABCC was reorganized to the Radiation Effects Research Foundation (RERF) in 1975, which continued the work of the ABCC. Follow-up of vital status and cause of death is performed for all RERF cohorts, including the atomic bomb survivors (the Life Span Study: LSS), in utero survivors, and the children of the survivors (F₁). Cancer incidence is investigated for accessible subpopulations of the cohorts. Health examinations for subcohorts of the LSS and in utero survivors are conducted as the Adult Health Study (AHS); a program of health examinations for a subcohort of the F₁ study is called the F₁ Offspring Clinical Study (FOCS). Participants of all clinical programs are asked to donate their blood and urine for storage and future biomedical investigations. Epidemiological studies have observed increased radiation risks for malignant diseases among survivors including those exposed in utero, and possible risks for some noncancer diseases. No increased risks due to parental exposure to radiation have been observed for malignancies or other diseases in F₁, but continuing investigations are required.

THYROID DISEASES AMONG ATOMIC BOMB SURVIVORS

Systematic epidemiological studies of Hiroshima and Nagasaki atomic bomb survivors have made substantial contributions to the understanding of radiation effects on human health. A recent study of atomic bomb survivors reported that an increased risk of thyroid cancer associated with childhood exposure might have persisted for more than 50 years after exposure. In analyses of non-cancer thyroid diseases, several cross-sectional studies, including the latest study focusing on survivors exposed in childhood, suggested that the risk of thyroid nodules increased, while risks of thyroid dysfunction and autoimmunity were not apparent several decades after radiation exposure. However, careful interpretations are needed because only limited data from cross-sectional studies are available. Further longitudinal studies are necessary to improve our understanding of the effect of radiation on the thyroid and its function.

Impact of early life exposure to ionizing radiation on influenza vaccine response in an elderly Japanese cohort

The objective of this study was to evaluate effects of whole body radiation exposure early in life on influenza vaccination immune responses much later in life. A total of 292 volunteers recruited from the cohort members of ongoing Adult Health Study (AHS) of Japanese atomic bomb (A-bomb) survivors completed this observational study spanning two influenza seasons (2011-2012 and 2012-2013). Peripheral blood samples were collected prior to and three weeks after vaccination. Serum hemagglutination inhibition (HAI) antibody titers were measured as well as concentrations of 25 cytokines and chemokines in culture supernatant from peripheral blood mononuclear cells, with and without in vitro stimulation with influenza vaccine. We found that influenza vaccination modestly enhanced serum HAI titers in this unique cohort of elderly subjects, with seroprotection ranging from 18 to 48% for specific antigen/season combinations. Twelve percent of subjects were seroprotected against all three vaccine antigens post-vaccination. Males were generally more likely to be seroprotected for one or more antigens post-vaccination, with no differences in vaccine responses based on age at vaccination or radiation exposure in early life. These results show that early life exposure to ionizing radiation does not prevent responses of elderly A-bomb survivors to seasonal influenza vaccine.

Radiation-related thyroid autoimmunity and dysfunction

The thyroid gland is vulnerable not only to external radiation but also to internal radiation, because the thyroid cells can incorporate radioactive iodine when synthesizing thyroid hormones. Since radiation-induction of thyroid neoplasia, including thyroid cancer, is well recognized, the data on radiation-related thyroid autoimmunity and dysfunction are summarized and reviewed. High-dose irradiation, irrespective of being external or internal, is strongly associated with a risk of hypothyroidism (with the prevalence ranging from 2.4% to 31%) and of Graves' hyperthyroidism (with the prevalence being up to 5%). It is easy to understand that high-dose irradiation induces hypothyroidism with some frequency, because high-dose irradiation destroys the thyroid gland. On the other hand, the basis for development of hyperthyroidism is mechanistically unclear, and it is merely speculative that autoantigens may be released from damaged thyroid glands and recognized by the immune system, leading to the development of anti-thyrotropin receptor antibodies and Graves' hyperthyroidism in subjects who are immunologically predisposed to this ailment. In contrast, the data on moderate to low-dose irradiation on thyroid autoimmunity and dysfunction are inconsistent. Although it is difficult to draw a definitive conclusion, some data may suggest a transient effect of moderate- to low-dose irradiation on hypothyroidism and autoimmune thyroiditis, implying that the effect, if it exists, is reversible. Finally, no report has shown a statistically significant increase in the prevalence of moderate- to low-dose irradiation-induced Graves' hyperthyroidism.

Radiation-induced inflammation and autoimmune diseases

Currently, ionizing radiation (IR) plays a key role in the agricultural and medical industry, while accidental exposure resulting from leakage of radioactive sources or radiological terrorism is a serious concern. Exposure to IR has various detrimental effects on normal tissues. Although an increased risk of carcinogenesis is the best-known long-term consequence of IR, evidence has shown that other diseases, particularly diseases related to inflammation, are common disorders among irradiated people. Autoimmune disorders are among the various types of immune diseases that have been investigated among exposed people. Thyroid diseases and diabetes are two autoimmune diseases potentially induced by IR. However, the precise mechanisms of IR-induced thyroid diseases and diabetes remain to be elucidated, and several studies have shown that chronic increased levels of inflammatory cytokines after exposure play a pivotal role. Thus, cytokines, including interleukin-1(IL-1), tumor necrosis factor (TNF-α) and interferon gamma (IFN-γ), play a key role in chronic oxidative damage following exposure to IR. Additionally, these cytokines change the secretion of insulin and thyroid-stimulating hormone(TSH). It is likely that the management of inflammation and oxidative damage is one of the best strategies for the amelioration of these diseases after a radiological or nuclear disaster. In the present study, we reviewed the evidence of radiation-induced diabetes and thyroid diseases, as well as the potential roles of inflammatory responses. In addition, we proposed that the mitigation of inflammatory and oxidative damage markers after exposure to IR may reduce the incidence of these diseases among individuals exposed to radiation.

Risk of Thyroid Nodules in Residents of Belarus Exposed to Chernobyl Fallout as Children and Adolescents

CONTEXT

Although radiation exposure is an important predictor of thyroid cancer on diagnosis of a thyroid nodule, the relationship between childhood radiation exposure and thyroid nodules has not been comprehensively evaluated.

OBJECTIVE

To examine the association between internal I-131 thyroid dose and thyroid nodules in young adults exposed during childhood.

DESIGN, SETTING, AND PARTICIPANTS

In this cross-sectional study, we screened residents of Belarus aged ≤18 years at the time of the Chernobyl nuclear accident for thyroid disease (median age, 21 years) with thyroid palpation, ultrasonography, blood/urine analysis, and medical follow-up when appropriate. Eligible participants (N = 11,421) had intact thyroid glands and doses based on direct individual thyroid activity measurements.

MAIN OUTCOME MEASURES

Excess odds ratios per Gray (EOR/Gy, scaled at age 5 years at exposure) for any thyroid nodule and for nodules grouped by cytology/histology, diameter size, and singularity.

RESULTS

Risk of any thyroid nodule increased significantly with I-131 dose and, for a given dose, with younger age at exposure. The EOR/Gy (95% confidence intervals) for neoplastic nodules (3.82; 0.87 to 15.52) was significantly higher than for nonneoplastic nodules (0.32; <0.03 to 0.70) and did not vary by size; whereas the EOR/Gy for nonneoplastic nodules did vary by size (P = 0.02) and was 1.55 (0.36 to 5.46) for nodules ≥10 mm and 0.02 (<-0.02 to 0.70) for nodules <10 mm. EORs/Gy for single and multiple nodules were comparable.

CONCLUSIONS

Childhood exposure to internal I-131 is associated with increased risk of neoplastic thyroid nodules of any size and nonneoplastic nodules ≥10 mm.

Thyroid Dysfunction and Autoimmune Thyroid Diseases Among Atomic Bomb Survivors Exposed in Childhood

CONTEXT

The risk of thyroid cancer increases and persists for decades among individuals exposed to ionizing radiation in childhood, although the long-term effects of childhood exposure to medium to low doses of radiation on thyroid dysfunction and autoimmune thyroid diseases have remained unclear.

OBJECTIVE

To evaluate radiation dose responses for the prevalence of thyroid dysfunction and autoimmune thyroid disease among atomic bomb survivors exposed in childhood.

DESIGN, SETTING, AND PARTICIPANTS

Hiroshima and Nagasaki atomic bomb survivors who were younger than 10 years old at exposure underwent thyroid examinations at the Radiation Effects Research Foundation between 2007 and 2011, which was 62 to 66 years after the bombing. Data from 2668 participants (mean age, 68.2 years; 1455 women) with known atomic bomb thyroid radiation doses (mean dose, 0.182 Gy; dose range, 0 to 4.040 Gy) were analyzed.

MAIN OUTCOME AND MEASURES

Dose-response relationships between atomic bomb radiation dose and the prevalence of hypothyroidism, hyperthyroidism (Graves' disease), and positive for antithyroid antibodies.

RESULTS

Prevalences were determined for hypothyroidism (129 cases, 7.8%), hyperthyroidism (32 cases of Graves' disease, 1.2%), and positive for antithyroid antibodies (573 cases, 21.5%). None of these was associated with thyroid radiation dose. Neither thyroid antibody-positive nor -negative hypothyroidism was associated with thyroid radiation dose. Additional analyses using alternative definitions of hypothyroidism and hyperthyroidism found that radiation dose responses were not significant.

CONCLUSIONS

Radiation effects on thyroid dysfunction and autoimmune thyroid diseases were not observed among atomic bomb survivors exposed in childhood, at 62 to 66 years earlier. The cross-sectional design and survival bias were limitations of this study.

Guidelines for the treatment of childhood-onset Graves' disease in Japan, 2016

Purpose behind developing these guidelines: Over one decade ago, the “Guidelines for the Treatment of Graves’ Disease with Antithyroid Drug, 2006” (Japan Thyroid Association (JTA)) were published as the standard drug therapy protocol for Graves’ disease. The “Guidelines for the Treatment of Childhood-Onset Graves’ Disease with Antithyroid Drug in Japan, 2008” were published to provide guidance on the treatment of pediatric patients. Based on new evidence, a revised version of the “Guidelines for the Treatment of Graves’ Disease with Antithyroid Drug, 2006” (JTA) was published in 2011, combined with the “Handbook of Radioiodine Therapy for Graves’ Disease 2007” (JTA). Subsequently, newer findings on pediatric Graves’ disease have been reported. Propylthiouracil (PTU)-induced serious hepatopathy is an important problem in pediatric patients. The American Thyroid Association’s guidelines suggest that, in principle, physicians must not administer PTU to children. On the other hand, the “Guidelines for the Treatment of Graves’ Disease with Antithyroid Drug, 2011” (JTA) state that radioiodine therapy is no longer considered a “fundamental contraindication” in children. Therefore, the “Guidelines for the Treatment of Childhood-Onset Graves’ Disease with Antithyroid Drug in Japan, 2008” required revision.

Thyroid-Stimulating Hormone, Thyroid Hormones, and Risk of Papillary Thyroid Cancer: A Nested Case-Control Study

Background: The effects of thyroid-stimulating hormone (TSH) and thyroid hormones on the development of human papillary thyroid cancer (PTC) remain poorly understood.Methods: The study population consisted of 741 (341 women, 400 men) histologically confirmed PTC cases and 741 matched controls with prediagnostic serum samples stored in the Department of Defense Serum Repository. Concentrations of TSH, total T3, total T4, and free T4 were measured in serum samples. Conditional logistic regression models were used to calculate ORs and 95% confidence intervals (CI).Results: The median time between blood draw and PTC diagnosis was 1,454 days. Compared with the middle tertile of TSH levels within the normal range, serum TSH levels below the normal range were associated with an elevated risk of PTC among women (OR, 3.74; 95% CI, 1.53-9.19) but not men. TSH levels above the normal range were associated with an increased risk of PTC among men (OR, 1.96; 95% CI, 1.04-3.66) but not women. The risk of PTC decreased with increasing TSH levels within the normal range among both men and women (P_trend = 0.0005 and 0.041, respectively).Conclusions: We found a significantly increased risk of PTC associated with TSH levels below the normal range among women and with TSH levels above the normal range among men. An inverse association between PTC and TSH levels within the normal range was observed among both men and women.Impact: These results could have significant clinical implications for physicians who are managing patients with abnormal thyroid functions and those with thyroidectomy. Cancer Epidemiol Biomarkers Prev; 26(8); 1209-18. ©2017 AACR.

Radiation exposure and thyroid cancer: a review

The association between radiation exposure and the occurrence of thyroid cancer has been well documented, and the two main risk factors for the development of a thyroid cancer are the radiation dose delivered to the thyroid gland and the age at exposure. The risk increases after exposure to a mean dose of more than 0.05-0.1 Gy (50-100mGy). The risk is more important during childhood and decreases with increased age at exposure, being low in adults. After exposure, the minimum latency period before the appearance of thyroid cancers is 5 to 10 years. Papillary carcinoma (PTC) is the most frequent form of thyroid carcinoma diagnosed after radiation exposure, with a higher prevalence of the solid subtype in young children with a short latency period and of the classical subtype in cases with a longer latency period after exposure. Molecular alterations, including intra-chromosomal rearrangements, are frequently found. Among them, RET/PTC rearrangements are the most frequent. Current research is directed on the mechanism of genetic alterations induced by radiation and on a molecular signature that can identify the origin of thyroid carcinoma after a known or suspected exposure to radiation.

Insulin Resistance: Any Role in the Changing Epidemiology of Thyroid Cancer?

In the past few decades, the incidence of thyroid cancer (TC), namely of its papillary hystotype (PTC), has shown a steady increase worldwide, which has been attributed at least in part to the increasing diagnosis of early stage tumors. However, some evidence suggests that environmental and lifestyle factors can also play a role. Among the potential risk factors involved in the changing epidemiology of TC, particular attention has been drawn to insulin-resistance and related metabolic disorders, such as obesity, type 2 diabetes, and metabolic syndrome, which have been also rapidly increasing worldwide due to widespread dietary and lifestyle changes. In accordance with this possibility, various epidemiological studies have indeed gathered substantial evidence that insulin resistance-related metabolic disorders might be associated with an increased TC risk either through hyperinsulinemia or by affecting other TC risk factors including iodine deficiency, elevated thyroid stimulating hormone, estrogen-dependent signaling, chronic autoimmune thyroiditis, and others. This review summarizes the current literature evaluating the relationship between metabolic disorders characterized by insulin resistance and the risk for TC as well as the possible underlying mechanisms. The potential implications of such association in TC prevention and therapy are discussed.

Evaluation of thyroid antibodies and benign disease prevalence among young adults exposed to (131)I more than 25 years after the accident at the Chernobyl Nuclear Power Plant

Background. The Chernobyl Nuclear Power Plant (CNPP) accident exposed a large number of inhabitants to internal ¹³¹I radiation. The associations between internal ¹³¹I exposure and thyroid autoimmunity and benign thyroid diseases remain controversial in the population living in the contaminated area around the CNNP. In this study, we evaluate the association of ¹³¹I with benign thyroid diseases. Methods. We compared the prevalence of Anti-Thyroid Autoantibodies (ATAs), thyroid function, and prevalence of thyroid ultrasound finding outcomes in 300 residents of the contaminated area of Ukraine who were 0–5 years of age at the time of the CNPP accident (group 1) and 300 sex-matched residents who were born after the accident (group 2). Results. We did not find any differences of the prevalence of Antithyroglobulin Antibodies (TGAb) positive, Antithyroid Peroxidase Antibodies (TPOAb) positive, and TGAb and/or TPOAb positive between the study groups. (11.7% vs 10.3%; p = 0.602, 17.3% vs 13.0%; p = 0.136, 21.0% vs 17.3%; p = 0.254, respectively); after adjusting for age and sex, the prevalence was not associated with the ¹³¹I exposure status in the study groups. The prevalence of subclinical and overt hypothyroidism cases was not significantly different (p = 0.093 and p = 0.320) in the two groups, nor was the prevalence of goiter (p = 0.482). On the other hand, the prevalence of nodules was significantly higher in group 1 (p = 0.003), though not significantly so after adjustment for age and sex. Discussion. Working 26–27 years after the CNNP accident, we found no increased prevalence of ATAs or benign thyroid diseases in young adults exposed to ¹³¹I fallout during early childhood in the contaminated area of Ukraine. Long-term follow-up is needed to clarify the effects of radiation exposure on autoimmunity reaction in the thyroid.

Risk of thyroid follicular adenoma among children and adolescents in Belarus exposed to iodine-131 after the Chornobyl accident

Several studies reported an increased risk of thyroid cancer in children and adolescents exposed to radioactive iodines, chiefly iodine-131 ((131)I), after the 1986 Chornobyl (Ukrainian spelling) nuclear power plant accident. The risk of benign thyroid tumors following such radiation exposure is much less well known. We have previously reported a novel finding of significantly increased risk of thyroid follicular adenoma in a screening study of children and adolescents exposed to the Chornobyl fallout in Ukraine. To verify this finding, we analyzed baseline screening data from a cohort of 11,613 individuals aged ≤18 years at the time of the accident in Belarus (mean age at screening = 21 years). All participants had individual (131)I doses estimated from thyroid radioactivity measurements and were screened according to a standardized protocol. We found a significant linear dose response for 38 pathologically confirmed follicular adenoma cases. The excess odds ratio per gray of 2.22 (95% confidence interval: 0.41, 13.1) was similar in males and females but decreased significantly with increasing age at exposure (P < 0.01), with the highest radiation risks estimated for those exposed at <2 years of age. Follicular adenoma radiation risks were not significantly modified by most indicators of past and current iodine deficiency. The present study confirms the (131)I-associated increases in risk of follicular adenoma in the Ukrainian population and adds new evidence on the risk increasing with decreasing age at exposure.

Ultrasonographic evaluation of parathyroid hyperplasia in multiple endocrine neoplasia type 1: Positive correlation between parathyroid volume and circulating parathyroid hormone concentration

There are few reports on parathyroid ultrasonography of multiple endocrine neoplasia type 1 (MEN1). This study investigated the ultrasonographic features of parathyroid glands in 10 patients with MEN1 who underwent preoperative neck ultrasonography and parathyroidectomy between 2006 and 2010 at Toranomon Hospital. We retrospectively analyzed clinical features, laboratory and ultrasonographic data, and pathological diagnosis. A total of 38 parathyroid glands were surgically removed (three to five glands from each patient). All removed parathyroids were pathologically diagnosed as hyperplasia. Seven cases (70.0 %) had adenomatous thyroid nodules. Twenty-five enlarged parathyroid glands (65.8 %) were detected by preoperative ultrasonography with a detection rate of 81.8 % (9/11) and 59.3 % (16/27) for patients without and with adenomatous nodules, respectively. Total parathyroid gland weight and potentially predictable total parathyroid volume by preoperative ultrasonography were significantly correlated with preoperative serum intact parathyroid hormone (iPTH) concentration (R = 0.97, P < 0.001 and R = 0.96, P < 0.001, respectively). The equation used for prediction of the total volume by ultrasonography was 15 × iPTH (pg/ml) - 1,000 and that for total weight was 20 × iPTH (pg/ml) - 1,400. Although adenomatous nodules often coexisted with MEN1 and made identification of enlarged parathyroid glands by ultrasonography difficult, the positive correlation between the predictable parathyroid volume by ultrasonography and serum iPTH suggests that their measurement is useful in the preoperative detection and localization of enlarged parathyroid glands in patients with MEN1. Furthermore, the presence of parathyroid glands that should be resected can be predicted before surgery using the equation proposed here.

Association of radiation dose with prevalence of thyroid nodules among atomic bomb survivors exposed in childhood (2007-2011)

IMPORTANCE

Few studies have evaluated the association of radiation dose with thyroid nodules among adults exposed to radiation in childhood.

OBJECTIVE

To evaluate radiation dose responses on the prevalence of thyroid nodules in atomic bomb survivors exposed in childhood.

DESIGN, SETTING, AND PARTICIPANTS

This survey study investigated 3087 Hiroshima and Nagasaki atomic bomb survivors who were younger than 10 years at exposure and participated in the thyroid study of the Adult Health Study at the Radiation Effects Research Foundation. Thyroid examinations including thyroid ultrasonography were conducted between October 2007 and October 2011, and solid nodules underwent fine-needle aspiration biopsy. Data from 2668 participants (86.4% of the total participants; mean age, 68.2 years; 1213 men; and 1455 women) with known atomic bomb thyroid radiation doses (mean dose, 0.182 Gy; median dose, 0.018 Gy; dose range, 0-4.040 Gy) were analyzed.

MAIN OUTCOMES AND MEASURES

The prevalence of all thyroid nodules having a diameter of 10 mm or more (consisting of solid nodules [malignant and benign] and cysts), prevalence of small thyroid nodules that were less than 10 mm in diameter detected by ultrasonography, and atomic bomb radiation dose-responses.

RESULTS

Thyroid nodules with a diameter of 10 mm or more were identified in 470 participants (17.6%): solid nodules (427 cases [16.0%]), malignant tumors (47 cases [1.8%]), benign nodules (186 cases [7.0%]), and cysts (49 cases [1.8%]), and all were significantly associated with thyroid radiation dose. Excess odds ratios per gray unit were 1.65 (95% CI, 0.89-2.64) for all nodules, 1.72 (95% CI, 0.93-2.75) for solid nodules, 4.40 (95% CI, 1.75-9.97) for malignant tumors, 2.07 (95% CI, 1.16-3.39) for benign nodules, and 1.11 (95% CI, 0.15-3.12) for cysts. The interaction between age at exposure and the dose was significant for the prevalence of all nodules (P = .003) and solid nodules (P < .001), indicating that dose effects were significantly higher with earlier childhood exposure. No interactions were seen for sex, family history of thyroid disease, antithyroid antibodies, or seaweed intake. No dose-response relationships were observed for small (<10-mm diameter) thyroid nodules.

CONCLUSIONS AND RELEVANCE

Radiation effects on thyroid nodules exist in atomic bomb survivors 62 to 66 years after their exposure in childhood. However, radiation exposure is not associated with small thyroid nodules.

The influence of the environment on the development of thyroid tumors: a new appraisal

Most epidemiological studies concerning differentiated thyroid cancers (DTC) indicate an increasing incidence over the last two decades. This increase might be partially explained by the better access to health services worldwide, but clinicopathological analyses do not fully support this hypothesis, indicating that there are carcinogenetic factors behind this noticeable increasing incidence. Although we have undoubtedly understood the biology and molecular pathways underlying thyroid carcinogenesis in a better way, we have made very little progresses in identifying a risk profile for DTC, and our knowledge of risk factors is very similar to what we knew 30-40 years ago. In addition to ionizing radiation exposure, the most documented and established risk factor for DTC, we also investigated the role of other factors, including eating habits, tobacco smoking, living in a volcanic area, xenobiotics, and viruses, which could be involved in thyroid carcinogenesis, thus, contributing to the increase in DTC incidence rates observed.

Evaluation of radiation exposure of medical staff during CT-guided interventions

PURPOSE

The purpose of this prospective study was to investigate absolute radiation exposure values and factors that influence radiation exposure of interventionists during CT-guided interventions (CTGIs). To our knowledge, no data exist regarding the radiation dose to which the interventionist is exposed during these procedures.

METHODS

Absolute radiation dose values from a total of 131 CTGIs were analyzed. Radiation dose values were collected by thermoluminescent dosimeters that were positioned above the lead protection being worn, on the forehead, thyroid, chest, gonads, and right and left hand and foot. The radiation doses were analyzed with respect to the experience level of the person performing the procedure, the degree of difficulty measured on a 4-point Likert scale, the lesion size measured on a 3-point Likert scale, and the CT system used.

RESULTS

Median whole-body dose was 12 μSv. With the exception of the forehead, all whole-body radiation doses were statistically significantly lower in CTGIs performed using the modern dual-source CT system compared with the 16-slice multi-detector CT. For CTGIs rated as more complex, the radiation exposure of the radiologist performing the procedure was statistically significantly higher, with the exception of the left hand. A statistically significantly lower median whole-body dose was measured for inexperienced compared with experienced radiologists. However, a few dose measurements of more than 1 mSv were found at the right hand.

CONCLUSIONS

Radiation exposure measured during CTGIs is low (<50 μSv). Because the radiation dose was higher in more-complex interventions and for 16-slice multi-detector row CT, inexperienced radiologists should focus on less-complex procedures.

The Brazilian consensus for the diagnosis and treatment of hyperthyroidism: recommendations by the Thyroid Department of the Brazilian Society of Endocrinology and Metabolism

INTRODUCTION

Hyperthyroidism is characterized by increased synthesis and release of thyroid hormones by the thyroid gland. Thyrotoxicosis refers to the clinical syndrome resulting from excessive circulating thyroid hormones, secondary to hyperthyroidism or due to other causes. This article describes evidence-based guidelines for the clinical management of thyrotoxicosis.

OBJECTIVE

This consensus, developed by Brazilian experts and sponsored by the Department of Thyroid Brazilian Society of Endocrinology and Metabolism, aims to address the management, diagnosis and treatment of patients with thyrotoxicosis, according to the most recent evidence from the literature and appropriate for the clinical reality of Brazil.

MATERIALS AND METHODS

After structuring clinical questions, search for evidence was made available in the literature, initially in the database MedLine, PubMed and Embase databases and subsequently in SciELO - Lilacs. The strength of evidence was evaluated by Oxford classification system was established from the study design used, considering the best available evidence for each question.

RESULTS

We have defined 13 questions about the initial clinical approach for the diagnosis and treatment that resulted in 53 recommendations, including the etiology, treatment with antithyroid drugs, radioactive iodine and surgery. We also addressed hyperthyroidism in children, teenagers or pregnant patients, and management of hyperthyroidism in patients with Graves' ophthalmopathy and various other causes of thyrotoxicosis.

CONCLUSIONS

The clinical diagnosis of hyperthyroidism usually offers no difficulty and should be made with measurements of serum TSH and thyroid hormones. The treatment can be performed with antithyroid drugs, surgery or administration of radioactive iodine according to the etiology of thyrotoxicosis, local availability of methods and preferences of the attending physician and patient.

Coexistence of papillary thyroid cancer and Hashimoto thyroiditis in children: report of 3 cases

This report documents 3 pediatric papillary thyroid carcinoma cases with associated Hashimoto thyroiditis. In all 3 cases, hypoechoic nodules accompanied by multiple echogenic spots were noted on sonography of the thyroid. Hashimoto thyroiditis was suspected on the basis of positive thyroid autoantibody test results and pathologic examinations of thyroidectomy specimens, which revealed chronic thyroiditis with lymphocytic infiltration as the background of papillary thyroid carcinoma development. The potential for papillary carcinoma development warrants close follow-up, and meticulous sonographic examinations must be performed in children with Hashimoto thyroiditis.

Quantification of cancer risk of each clinical and ultrasonographic suspicious feature of thyroid nodules: a systematic review and meta-analysis

OBJECTIVE

In order to quantify the risk of malignancy of clinical and ultrasonographic features of thyroid nodules (TNs), we did a systematic review and meta-analysis of published studies.

METHODS

We did a literature search in MEDLINE for studies published from 1st January 1989 until 31st December 2012. Studies were considered eligible if they investigated the association between at least one clinical/ultrasonographic feature and the risk of malignancy, did not have exclusion criteria for the detected nodules, had histologically confirmed the diagnoses of malignancy, and had a univariable analysis available. Two reviewers independently extracted data on study characteristics and outcomes.

RESULTS

The meta-analysis included 41 studies, for a total of 29678 TN. A higher risk of malignancy expressed in odds ratio (OR) was found for the following: nodule height greater than width (OR: 10.15), absent halo sign (OR: 7.14), microcalcifications (OR: 6.76), irregular margins (OR: 6.12), hypoechogenicity (OR: 5.07), solid nodule structure (OR: 4.69), intranodular vascularization (OR: 3.76), family history of thyroid carcinoma (OR: 2.29), nodule size ≥4 cm (OR: 1.63), single nodule (OR: 1.43), history of head/neck irradiation (OR: 1.29), and male gender (OR: 1.22). Interestingly, meta-regression analysis showed a higher risk of malignancy for hypoechoic nodules in iodine-sufficient than in iodine-deficient geographical areas.

CONCLUSIONS

The current meta-analysis verified and weighed out each suspicious clinical and ultrasonographic TN feature. The highest risk was found for nodule height greater than width, absent halo sign, and microcalcifications for ultrasonographic features and family history of thyroid carcinoma for clinical features. A meta-analysis-derived grading system of TN malignancy risk, validated on a large prospective cohort, could be a useful tool in TN diagnostic work-up.