Background
Recent studies of children and adolescents exposed to radioactive iodine-131 (I-131) after the 1986 Chernobyl nuclear accident in Ukraine showed significant dose-related increase in the risk of thyroid cancer, but the association of radiation doses with tumor histological and morphological features is not clear.
Methods
A cohort of 11,664 individuals in Belarus ≤18 years at the time of the accident underwent three cycles of thyroid screening in 1997-2008. I-131 thyroid doses were estimated from individual thyroid activity measurements taken within two months after the accident and dosimetric data from questionnaires. Demographic, clinical and pathological characteristics of thyroid cancer cases were analyzed using one-way analysis of variance, chi-square or Fisher's exact tests, and logistic regression.
Results
As a result of screening, 158 thyroid cancers were identified. The majority of cases had T1a and T1b tumors (93.7%), with many regional N1 (60.6%) but few distant M1 (<1%) metastases. Higher I-131 doses were associated with higher frequency of solid or diffuse sclerosing variants of thyroid cancer (P<0.01) and histological features of cancer aggressiveness, such as lymphatic vessel invasion, intrathyroidal infiltration, and multifocality (all P<0.03). Latency was not correlated with radiation dose. Fifty-two cases of self-reported thyroid cancers diagnosed prior to 1997 were younger at the time of the accident and had a higher percentage of solid variant cancers compared to screening-detected cases (all P<0.0001).
Conclusions
I-131 thyroid radiation doses were associated with significantly higher frequency of solid or diffuse sclerosing variants of thyroid cancer and various features of tumor aggressiveness.
The Belarus-American (BelAm) Thyroid Study cohort consists of persons 0–18 years of age at the time of exposure to radioiodines from the 1986 Chernobyl nuclear power plant accident who have undergone serial thyroid screenings with referral for fine-needle aspiration biopsy (FNAB) using standardized criteria. We investigated thyrocyte nuclear abnormalities in cytological samples from FNABs in 50 BelAm subjects with thyroid nodules and 43 control patients from Leningrad, Russia, unexposed to Chernobyl fallout. Nuclear abnormalities such as internuclear chromosome bridges and derivative nuclei with broken bridges (i.e., “tailed” nuclei), formed from dicentric and ring chromosomes, may be cellular markers of radiation exposure. In the exposed BelAm cohort, thyrocytes with bridges were present in 80% of subjects with single-nodular goiters compared with 27% of unexposed controls. The average frequency of thyrocytes with bridges was also significantly higher in the BelAm subjects than in controls as was the mean frequency of thyrocytes with tailed nuclei. In the case of multi-nodular goiters, thyrocytes with bridges were present in 75.0% of exposed BelAm patients compared with 16.7% of unexposed controls. Thyrocytes with tailed nuclei were observed in all of the BelAm subjects but in only 35% of controls, and the mean frequency of tailed nuclei was significantly higher. Unusually long bridges were detected in 29% of BelAm patients with single-nodular goiters and 35% of cases with multi-nodular goiters, while no such abnormalities were observed in the follicular thyroid epithelium of patients from the Leningrad region. Further study is needed to understand whether these phenomena represent irradiation consequences in the human organism.
Проанализировано 75 эхографических снимков щитовидной железы с гистологически верифицированным диагнозом: «рак». Все больные дети находились на момент Чернобыльской аварии в Гомельской области и проживали в условиях зобной эндемии и действия малых доз радиации, сложившихся после аварии. Полученные в нашем исследовании данные еще раз говорят о сложности дифференциальной диагностики опухолей ЩЖ размером менее 1 см, при которой особое внимание следует уделять таким эхосемиотических признакам, как наличие гипоэхогенности и сочетание гипо- и изоэхогенности, неоднородность структуры узлов и наличие одиночных кальцинатов, которые в комплексе с клинико-лабораторными данными позволяют уточнить характер узловых образований у детей.
In article hormonal status and its influence on physical development of the girls in the first phase of the period sexual maturations, prominent citizens of unfavorable ecologic areas of Gomel oblast were under investigation. Basing on correlations and cluster analyzes some connections between hormonal levels and anthropometric parameters were shown.
Introduction. Sustainable development of territories affected by the Chernobyl disaster, require a number of managerial decisions, to reduce the level of radiophobia and psycho-emotional stress in society. Aim. To study the relationship between the indicators of the incidence of hemoblastosis with the density of contamination of territories with radioactive elements. Material and methods. An ecological population epidemiological study based on the calculation of the correlation coefficients of the incidence rates of hemoblastosis with the density of radioactive contamination. Results. There is no connection between the incidence of hemoblastosis and the density of radioactive contamination of territories. A statistically significant risk of multiple myeloma is observed in areas with a 137Cs contamination density of 1.0-4.99 Ci/km2. There was a statistically significant strong (r> 0.95) correlation between the crude incidence rate and standardized by age, sex and place of residence incidence ratio. The presence of strong correlations between these indicators give the possibility to use crude incidence rate instead of SIR in the analysis of morbidity by rayons. Conclusions. No correlation was found between the incidence of hemoblastosis and the density of radioactive contamination.
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