RESUMO
In April 1986, the Chernobyl nuclear accident resulted in wide-scale contamination of Belarus with significantly elevated levels of radioiodine isotopes, mainly iodine-131 (131I), and long-lived radiocaesium isotopes, mainly caesium-137 (137Cs). Various groups of the population were affected by exposure to ionising radiation, including pregnant women and their foetuses. This paper describes the methods and results related to the establishment of a cohort of 2965 Belarusian people exposed in utero due to Chernobyl fallout. The cohort consists of individuals whose mothers resided in the most radioactively contaminated areas in Belarus at the time of the accident. Prenatal and postnatal doses to the thyroid due to intake of 131I, external irradiation and ingestion of radiocaesium isotopes were estimated for all cohort members. Ongoing research on this unique cohort will provide important information on adverse health effects following prenatal and postnatal exposure to radioiodine and radiocaesium isotopes, for which available epidemiological data are scant.
Assuntos
Acidente Nuclear de Chernobyl , Feto/efeitos da radiação , Gestantes , Cinza Radioativa , Adulto , Radioisótopos de Césio , Exposição Ambiental , Feminino , Humanos , Radioisótopos do Iodo , Gravidez , Exposição à Radiação , Radiação Ionizante , República de Belarus/epidemiologiaRESUMO
BACKGROUND: While an increased risk of thyroid cancer from post-Chernobyl exposure to Iodine-131 (I-131) in children and adolescents has been well-documented, risks of other cancers or leukemia as a result of residence in radioactively contaminated areas remain uncertain. METHODS: We studied non-thyroid cancer incidence in a cohort of about 12,000 individuals from Belarus exposed under age of 18 years to Chernobyl fallout (median age at the time of Chernobyl accident of 7.9 years). During 15 years of follow-up from1997 through 2011, 54 incident cancers excluding thyroid were identified in the study cohort with 142,968 person-years at risk. We performed Standardized Incidence Ratio (SIR) analysis of all solid cancers excluding thyroid (n=42), of leukemia (n=6) and of lymphoma (n=6). RESULTS: We found no significant increase in the incidence of non-thyroid solid cancer (SIR=0.83, 95% Confidence Interval [CI]: 0.61; 1.11), lymphoma (SIR=0.66, 95% CI: 0.26; 1.33) or leukemia (SIR=1.78, 95% CI: 0.71; 3.61) in the study cohort as compared with the sex-, age- and calendar-time-specific national rates. These findings may in part reflect the relatively young age of study subjects (median attained age of 33.4 years), and long latency for some radiation-related solid cancers. CONCLUSIONS: We found no evidence of statistically significant increases in solid cancer, lymphoma and leukemia incidence 25 years after childhood exposure in the study cohort; however, it is important to continue follow-up non-thyroid cancers in individuals exposed to low-level radiation at radiosensitive ages.
Assuntos
Acidente Nuclear de Chernobyl , Leucemia/epidemiologia , Linfoma/epidemiologia , Neoplasias Induzidas por Radiação/epidemiologia , Adolescente , Criança , Pré-Escolar , Estudos de Coortes , Humanos , Incidência , Lactente , Recém-Nascido , Leucemia/etiologia , Linfoma/etiologia , Neoplasias Induzidas por Radiação/etiologia , República de Belarus/epidemiologia , Fatores de RiscoRESUMO
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.
Assuntos
Adenoma/epidemiologia , Adenoma/etiologia , Acidente Nuclear de Chernobyl , Radioisótopos do Iodo/toxicidade , Neoplasias Induzidas por Radiação/etiologia , Neoplasias da Glândula Tireoide/etiologia , Adolescente , Adulto , Criança , Relação Dose-Resposta à Radiação , Exposição Ambiental , Feminino , Humanos , Masculino , Neoplasias Induzidas por Radiação/epidemiologia , Prevalência , Fatores de Risco , Neoplasias da Glândula Tireoide/epidemiologiaRESUMO
BACKGROUND: Recent studies of children and adolescents who were exposed to radioactive iodine-131 (I-131) after the 1986 Chernobyl nuclear accident in Ukraine exhibited a significant dose-related increase in the risk of thyroid cancer, but the association of radiation doses with tumor histologic and morphologic features is not clear. METHODS: A cohort of 11,664 individuals in Belarus who were aged ≤18 years at the time of the accident underwent 3 cycles of thyroid screening during 1997 to 2008. I-131 thyroid doses were estimated from individual thyroid activity measurements taken within 2 months after the accident and from dosimetric questionnaire data. Demographic, clinical, and tumor pathologic characteristics of the patients with thyroid cancer were analyzed using 1-way analysis of variance, chi-square tests or Fisher exact tests, and logistic regression. RESULTS: In total, 158 thyroid cancers were identified as a result of screening. The majority of patients had T1a and T1b tumors (93.7%), with many positive regional lymph nodes (N1; 60.6%) but few distant metastases (M1; <1%). Higher I-131 doses were associated with higher frequency of solid and diffuse sclerosing variants of thyroid cancer (P < .01) and histologic features of cancer aggressiveness, such as lymphatic vessel invasion, intrathyroidal infiltration, and multifocality (all P < .03). Latency was not correlated with radiation dose. Fifty-two patients with self-reported thyroid cancers which were diagnosed before 1997 were younger at the time of the accident and had a higher percentage of solid variant cancers compared with patients who had screening-detected thyroid cancers (all P < .0001). CONCLUSIONS: I-131 thyroid radiation doses were associated with a significantly greater frequency of solid and diffuse sclerosing variants of thyroid cancer and various features of tumor aggressiveness.
Assuntos
Acidente Nuclear de Chernobyl , Radioisótopos do Iodo/administração & dosagem , Neoplasias Induzidas por Radiação/epidemiologia , Neoplasias Induzidas por Radiação/patologia , Neoplasias da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/patologia , Adolescente , Adulto , Criança , Estudos de Coortes , Feminino , Humanos , Modelos Logísticos , Masculino , República de Belarus/epidemiologia , Adulto JovemRESUMO
OBJECTIVE: Serum thyroglobulin (Tg) has been associated with a number of thyroid disorders and has been proposed as an indicator of iodine deficiency in a population. However, few studies have addressed the epidemiology of Tg in a population-based setting or in the context of exposure to radioactive iodine-131 (I-131). Our objective was to evaluate baseline levels of Tg in relation to sociodemographic characteristics, iodine status and thyroid function for individuals exposed to I-131. DESIGN: A population-based cohort assembled in Belarus following the Chornobyl accident provided demographic factors, clinical data and physiological measurements. PARTICIPANTS: Our analytical sample included 10,344 subjects of whom 7890 had no thyroid disease and 2454 had evidence of structural or functional thyroid abnormality. MEASUREMENTS: Standardized assays were used to measure serum Tg, urinary iodine, TSH and antibodies to Tg and thyroid peroxidase. Ultrasound was used to assess the presence of nodules and estimate thyroid volume. RESULTS: In the fully adjusted model, percent change in Tg was significantly increased among females, smokers and subjects of older age and Tg increased with decreasing urinary iodine concentration, increasing serum TSH and increasing thyroid volume (P-values for trend <0·0001), and presence of thyroid nodules (P < 0·05). We found a complex interaction between region of residence, rural/urban living, presence/absence of thyroid abnormalities and serum Tg (P < 0·0001). CONCLUSIONS: In residents of Belarus, serum Tg is significantly related to presence of thyroid abnormalities as well as indicators of thyroid function and iodine deficiency and, therefore, could be used to characterize the iodine status and thyroid function of individuals in the context of epidemiological study.
Assuntos
Tireoglobulina/biossíntese , Doenças da Glândula Tireoide/sangue , Glândula Tireoide/patologia , Adolescente , Adulto , Anticorpos/sangue , Anticorpos/imunologia , Acidente Nuclear de Chernobyl , Criança , Estudos de Coortes , Feminino , Humanos , Iodeto Peroxidase/imunologia , Radioisótopos do Iodo/urina , Masculino , Análise Multivariada , República de Belarus/epidemiologia , População Rural/estatística & dados numéricos , Fatores Socioeconômicos , Tireoglobulina/imunologia , Doenças da Glândula Tireoide/epidemiologia , Doenças da Glândula Tireoide/urina , Testes de Função Tireóidea , Glândula Tireoide/metabolismo , Tireotropina/sangue , Tireotropina/metabolismo , População Urbana/estatística & dados numéricos , Adulto JovemRESUMO
Olutasidenib (FT-2102) is a potent, selective, oral, small-molecule inhibitor of mutant isocitrate dehydrogenase 1 (mIDH1). Overall, 153 IDH1 inhibitor-naive patients with mIDH1R132 relapsed/refractory (R/R) acute myeloid leukemia (AML) received olutasidenib monotherapy 150 mg twice daily in the pivotal cohort of this study. The median age of participants was 71 years (range, 32-87 years) and the median number of prior regimens received by patients was 2 (1-7). The rate of complete remission (CR) plus CR with partial hematologic recovery (CRh) was 35%, and the overall response rate was 48%. Response rates were similar in patients who had, and who had not, received prior venetoclax. With 55% of patients censored at the time of data cut-off, the median duration of CR/CRh was 25.9 months. The median duration of overall response was 11.7 months, and the median overall survival was 11.6 months. Of 86 patients who were transfusion dependent at baseline, a 56-day transfusion independence was achieved in 29 (34%), which included patients in all response groups. Grade 3 or 4 treatment-emergent adverse events (≥10%) were febrile neutropenia and anemia (n = 31; 20% each), thrombocytopenia (n = 25; 16%), and neutropenia (n = 20; 13%). Differentiation syndrome adverse events of special interest occurred in 22 (14%) patients, with 14 (9%) grade ≥3 and 1 fatal case reported. Overall, olutasidenib induced durable remissions and transfusion independence with a well-characterized and manageable side effect profile. The observed efficacy represents a therapeutic advance in this molecularly defined, poor-prognostic population of patients with mIDH1 R/R AML. This trial was registered at www.clinicaltrials.gov as #NCT02719574.
Assuntos
Leucemia Mieloide Aguda , Quinolinas , Humanos , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Piridinas , Quinolinas/uso terapêutico , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/induzido quimicamente , Prognóstico , Isocitrato Desidrogenase/genéticaRESUMO
Thyroid radiation doses were estimated for a cohort of 2,965 Belarusian persons who were exposed in utero and during early life to fallout from the Chernobyl nuclear power plant accident. Prenatal and postnatal doses to the thyroid due to intake of I, external irradiation from radionuclides deposited on the ground, and ingestion of cesium isotopes (Cs and Cs) were calculated for all cohort members. Dose estimation was based on personal interviews with subjects' mothers; the interviews collected data on subjects' residential history, consumption by mothers during time of pregnancy and breast-feeding, as well as consumption by subjects after birth. Direct instrumental measurements of radioactivity in mothers and the study subjects, if available, were also used for calculation of doses. Intake of I by mothers was found to be the predominant pathway for thyroid exposure for the study subjects. The average thyroid dose due to all exposure pathways was estimated to be 137 mGy (median dose of 25 mGy, maximal dose of 14.8 Gy), including 130 mGy (median dose of 17 mGy, maximal dose of 14.8 Gy) from I intake, 4.9 mGy (median dose of 3.0 mGy, maximal dose of 102 mGy) due to external irradiation, and 2.5 mGy (median dose of 1.7 mGy, maximal dose of 47 mGy) due to ingestion of Cs. The dose estimates will be used to evaluate the radiation-related risk of thyroid cancer and other thyroid diseases in this unique cohort.
Assuntos
Acidente Nuclear de Chernobyl , Feto/efeitos da radiação , Glândula Tireoide/efeitos da radiação , Adolescente , Radioisótopos de Césio , Estudos de Coortes , Feminino , Humanos , Neoplasias Induzidas por Radiação/etiologia , Gravidez , Doses de Radiação , Neoplasias da Glândula Tireoide/etiologia , Adulto JovemRESUMO
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.
Assuntos
Acidente Nuclear de Chernobyl , Neoplasias Induzidas por Radiação/etiologia , Nódulo da Glândula Tireoide/etiologia , Adolescente , Criança , Pré-Escolar , Relação Dose-Resposta à Radiação , Detecção Precoce de Câncer/métodos , Feminino , Humanos , Lactente , Recém-Nascido , Radioisótopos do Iodo/efeitos adversos , Masculino , Neoplasias Induzidas por Radiação/epidemiologia , República de Belarus/epidemiologia , Medição de Risco/métodos , Fatores de Risco , Nódulo da Glândula Tireoide/diagnóstico por imagem , Nódulo da Glândula Tireoide/epidemiologia , Nódulo da Glândula Tireoide/patologia , UltrassonografiaRESUMO
BACKGROUND: The excess incidence of thyroid cancer in Ukraine and Belarus observed a few years after the Chernobyl accident is considered to be largely the result of 131I released from the reactor. Although the Belarus thyroid cancer prevalence data has been previously analyzed, no account was taken of dose measurement error. METHODS: We examined dose-response patterns in a thyroid screening prevalence cohort of 11,732 persons aged under 18 at the time of the accident, diagnosed during 1996-2004, who had direct thyroid 131I activity measurement, and were resident in the most radio-actively contaminated regions of Belarus. Three methods of dose-error correction (regression calibration, Monte Carlo maximum likelihood, Bayesian Markov Chain Monte Carlo) were applied. RESULTS: There was a statistically significant (p<0.001) increasing dose-response for prevalent thyroid cancer, irrespective of regression-adjustment method used. Without adjustment for dose errors the excess odds ratio was 1.51 Gy- (95% CI 0.53, 3.86), which was reduced by 13% when regression-calibration adjustment was used, 1.31 Gy- (95% CI 0.47, 3.31). A Monte Carlo maximum likelihood method yielded an excess odds ratio of 1.48 Gy- (95% CI 0.53, 3.87), about 2% lower than the unadjusted analysis. The Bayesian method yielded a maximum posterior excess odds ratio of 1.16 Gy- (95% BCI 0.20, 4.32), 23% lower than the unadjusted analysis. There were borderline significant (p = 0.053-0.078) indications of downward curvature in the dose response, depending on the adjustment methods used. There were also borderline significant (p = 0.102) modifying effects of gender on the radiation dose trend, but no significant modifying effects of age at time of accident, or age at screening as modifiers of dose response (p>0.2). CONCLUSIONS: In summary, the relatively small contribution of unshared classical dose error in the current study results in comparatively modest effects on the regression parameters.
Assuntos
Acidente Nuclear de Chernobyl , Radioisótopos do Iodo/efeitos adversos , Neoplasias Induzidas por Radiação/epidemiologia , Neoplasias da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/etiologia , Adolescente , Adulto , Teorema de Bayes , Criança , Desastres , Relação Dose-Resposta à Radiação , Exposição Ambiental , Feminino , Humanos , Masculino , Cadeias de Markov , Modelos Estatísticos , Método de Monte Carlo , Reatores Nucleares , Prevalência , Reprodutibilidade dos Testes , República de Belarus , Fatores de Risco , Processos Estocásticos , Ucrânia , Incerteza , Adulto JovemRESUMO
The thyroid gland in children is one of the organs that is most sensitive to external exposure to X and gamma rays. However, data on the risk of thyroid cancer in children after exposure to radioactive iodines are sparse. The Chornobyl accident in Ukraine in 1986 led to the exposure of large populations to radioactive iodines, particularly (131)I. This paper describes an ongoing cohort study being conducted in Belarus and Ukraine that includes 25,161 subjects under the age of 18 years in 1986 who are being screened for thyroid diseases every 2 years. Individual thyroid doses are being estimated for all study subjects based on measurement of the radioactivity of the thyroid gland made in 1986 together with a radioecological model and interview data. Approximately 100 histologically confirmed thyroid cancers were detected as a consequence of the first round of screening. The data will enable fitting appropriate dose-response models, which are important in both radiation epidemiology and public health for prediction of risks from exposure to radioactive iodines from medical sources and any future nuclear accidents. Plans are to continue to follow-up the cohort for at least three screening cycles, which will lead to more precise estimates of risk.
Assuntos
Neoplasias Induzidas por Radiação/epidemiologia , Centrais Elétricas , Liberação Nociva de Radioativos , Doenças da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/epidemiologia , Adolescente , Adulto , Criança , Pré-Escolar , Estudos de Coortes , Relação Dose-Resposta à Radiação , Feminino , Humanos , Lactente , Recém-Nascido , Radioisótopos do Iodo , Masculino , Neoplasias Induzidas por Radiação/etiologia , Radiometria , Projetos de Pesquisa , Risco , Doenças da Glândula Tireoide/etiologia , Glândula Tireoide/efeitos da radiação , Neoplasias da Glândula Tireoide/etiologia , Fatores de Tempo , UcrâniaRESUMO
BACKGROUND: Thyroid dysfunction after exposure to low or moderate doses of radioactive iodine-131 (131I) at a young age is a public health concern. However, quantitative data are sparse concerning 131I-related risk of these common diseases. OBJECTIVE: Our goal was to assess the prevalence of thyroid dysfunction in association with 131I exposure during childhood (≤ 18 years) due to fallout from the Chernobyl accident. METHODS: We conducted a cross-sectional analysis of hypothyroidism, hyperthyroidism, autoimmune thyroiditis (AIT), serum concentrations of thyroid-stimulating hormone (TSH), and autoantibodies to thyroperoxidase (ATPO) in relation to measurement-based 131I dose estimates in a Belarusian cohort of 10,827 individuals screened for various thyroid diseases. RESULTS: Mean age at exposure (± SD) was 8.2 ± 5.0 years. Mean (median) estimated 131I thyroid dose was 0.54 (0.23) Gy (range, 0.001-26.6 Gy). We found significant positive associations of 131I dose with hypothyroidism (mainly subclinical and antibody-negative) and serum TSH concentration. The excess odds ratio per 1 Gy for hypothyroidism was 0.34 (95% CI: 0.15, 0.62) and varied significantly by age at exposure and at examination, presence of goiter, and urban/rural residency. We found no evidence of positive associations with antibody-positive hypothyroidism, hyperthyroidism, AIT, or elevated ATPO. CONCLUSIONS: The association between 131I dose and hypothyroidism in the Belarusian cohort is consistent with that previously reported for a Ukrainian cohort and strengthens evidence of the effect of environmental 131I exposure during childhood on hypothyroidism, but not other thyroid outcomes.
Assuntos
Iodo/toxicidade , Doenças da Glândula Tireoide/induzido quimicamente , Glândula Tireoide/fisiopatologia , Adolescente , Acidente Nuclear de Chernobyl , Distribuição de Qui-Quadrado , Criança , Pré-Escolar , Estudos de Coortes , Estudos Transversais , Relação Dose-Resposta à Radiação , Feminino , Humanos , Radioisótopos do Iodo/toxicidade , Funções Verossimilhança , Masculino , Razão de Chances , Prevalência , República de Belarus/epidemiologia , Doenças da Glândula Tireoide/sangue , Doenças da Glândula Tireoide/epidemiologiaRESUMO
OBJECTIVE: As the Internet has become a ubiquitous tool for health information, the use of Internet support groups for mental health concerns has grown. Despite the widespread use of these groups, little research has examined the efficacy and effectiveness of online communities for ameliorating mental health symptoms or factors that prompt people to seek online support rather than formal treatment. Our study addresses this gap in the literature by investigating Internet support group use as an alternative to formal mental health services. METHODS: Logistic regression was conducted with data from the 2008 National Survey on Drug Use and Health (NSDUH) to examine relationships among treatment beliefs, practical variables such as time and affordability, stigma, and use of Internet support groups among 2,532 survey participants who reported a need for mental health treatment but were not receiving formal services. RESULTS: Four significant predictors of Internet support group use emerged: fear of being hospitalized or taking medication (adjusted odds ratio [AOR]=8.81, 95% confidence interval [CI]=4.25-18.27), inadequate insurance coverage (AOR=3.22, CI=1.44-7.20), age 26-34 years (AOR=.22, CI=.07-.69), and age 35 or older (AOR=.21, CI=.08-.56). CONCLUSIONS: Fear of coercion and the costs of traditional mental health services were important predictors of Internet support group use. The finding that inadequate insurance coverage prompted people to seek Internet support aligns with a substantial literature regarding lack of financial resources and reduced access to treatment. Individuals' fears of hospitalization and of taking medication suggested that they may view formal treatment as potentially coercive. Further work is needed to decrease public stigma regarding mental health services and the conditions under which involuntary treatment occurs.
Assuntos
Conhecimentos, Atitudes e Prática em Saúde , Internet/estatística & dados numéricos , Transtornos Mentais/terapia , Serviços de Saúde Mental/estatística & dados numéricos , Grupos de Autoajuda/estatística & dados numéricos , Adolescente , Adulto , Coerção , Medo , Feminino , Acessibilidade aos Serviços de Saúde/economia , Humanos , Cobertura do Seguro , Modelos Logísticos , Masculino , Transtornos Mentais/psicologia , Serviços de Saúde Mental/economia , Preferência do Paciente/psicologia , Psicotrópicos , Estigma Social , Adulto JovemRESUMO
BACKGROUND: Because iodine deficiency can influence background rates of thyroid disease or modify radiation dose-response relationships, we compiled descriptive data on iodine status among participants in a Belarusian-American screening study who were exposed in childhood to radioiodine fallout from the Chornobyl nuclear accident. We have used the data from two consecutive screening cycles to examine whether indicators of iodine status changed before and after documented government initiatives to improve iodine intake. METHODS: Urinary iodine concentrations in spot samples and prevalence of diffuse goiter by palpation were assessed in 11,676 exposed subjects who were 18 years or younger at the time of the accident on April 26, 1986, and were screened beginning 11 years later in connection with the Belarus-American Thyroid Study. Data for the first ( January 1997-March 2001) and second (April 2001-December 2004) screening cycles, which largely correspond to time periods before and after official iodination efforts in 2000/2001, were compared for the cohort overall as well as by oblast of residence (i.e., state) and type of residency (urban/rural). RESULTS: Median urine iodine levels among cohort members increased significantly in the later period (111.5 mg/L) compared to the earlier (65.3 mg/L), with the cycle 2 level in the range defined as adequate iodine intake by the World Health Organization. During the same period, a significant decline in diffuse goiter prevalence was also observed. In both cycles, urinary iodine levels were lower in rural than in urban residents. Urinary iodine levels, but not rates of goiter, varied by oblast of residence. In both periods, adjusted median urine iodine concentrations were similar in Gomel and Minsk oblasts, where *89% of cohort members resided, and were lowest in Mogilev oblast. Yet Mogilev oblast and rural areas showed the most marked increases over time. CONCLUSIONS: Trends in urinary iodine concentrations and prevalence of diffuse goiter by palpation suggest that iodination efforts in Belarus were successful, with benefits extending to the most iodine-deficient populations. Iodine status should be considered when evaluating thyroid disease risk in radioiodine-exposed populations since it can change over time and may influence rates of disease and, possibly, dose-response relationships
Assuntos
Acidente Nuclear de Chernobyl , Bócio/epidemiologia , Iodo/urina , Adolescente , Criança , Pré-Escolar , Estudos de Coortes , Humanos , Lactente , Iodo/administração & dosagem , Neoplasias Induzidas por Radiação/epidemiologia , República de Belarus/epidemiologia , Cloreto de Sódio na Dieta/administração & dosagem , Doenças da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/epidemiologiaRESUMO
BACKGROUND: The Chernobyl accident resulted in an unprecedented number of radiation-induced thyroid cancers in young individuals as detected by national and international screening programs. The vast majority of thyroid malignancies were papillary carcinomas that, despite being similar by histopathology, displayed large variability in clinical course. The correlations between ultrasound (US) and clinicopathological features in young patients with radiation-induced thyroid cancer, however, have not been well studied. Because of the importance of US for deciding which subjects should have fine-needle aspiration biopsy, we assessed the US features of papillary thyroid carcinoma in patients exposed to Chernobyl fallouts. DESIGN: We performed a retrospective multivariate logistic regression analysis of US features, clinicopathological data, and the latency period between radiation exposure and the diagnosis of cancer in 94 patients who were 10.6-34.3 years old (16.5 +/- 6.2, mean +/- standard deviation) at the time of diagnosis and 0.1-18.0 years old (5.6 +/- 4.2) at the time of the Chernobyl accident. RESULTS: Nodules greater than 10 mm were associated with the higher frequency of irregular margins (p = 0.001), longer period of latency (p = 0.016), and bilateral lymph node involvement (p = 0.025). Irregular tumor margins correlated with the shorter period of latency (p = 0.009) and unilateral nodal disease (p = 0.010). Hypoechoic nodules were observed more frequently in female patients (p = 0.012), in the absence of halo (p = 0.003) or calcifications (p = 0.005). Hypoechogenicity also correlated with the shorter latency (p = 0.015) and younger age of patients (p = 0.048). CONCLUSIONS: Irregular nodule margins, a usual sign of malignancy, are less useful in detecting thyroid cancers in radiation-exposed patients with tumors less than 10 mm. Thyroid cancers that are detected after longer latent periods display less of the US features characteristic of a malignant process, while benign US features are observed more frequently. Therefore, we recommend fine-needle aspiration biopsy to ensure early diagnosis of thyroid cancer for patients with a history of radiation exposure, even if their nodules are less than 10 mm.