Risk assessment of radiation-induced thyroid cancers in Belarus

Assessment of incidence and mortality for thyroid cancers carried out for the Belarusian population is described in the present report. It is found that in the period of 1987-2000 about 4,400 radiation-induced thyroid cancers appeared in Belarus: 692 cancers among children and 3,709 cancers among adolescents and adults. The number of lethal thyroid cancers in this period of time in Belarus was assessed as about 350 cases. The excessive absolute risk, EAR, of thyroid cancer incidence assessed for the period of 1987-2000 on the basis of given data on the morbidity and the assessed collective thyroid dose of irradiation is (2.5 – 5.0) per 10 4 PYGy. The EAR value of thyroid cancer mortality is assessed as (0.20 -0.40) per 10 4 PYGy. The excessive relative risk, ERR, of thyroid cancer incidence is assessed as (11.2 – 22.4)/Gy. The radiation risks of thyroid cancers found in the present report are higher than the risk coefficients established for atomic bomb survivors that were irradiate...

Radiation research, 2006

The purpose of the present study was to analyze the thyroid cancer incidence risk after the Chernobyl accident and its degree of dependence on time and age. Data were analyzed for 1034 settlements in Ukraine and Belarus, in which more than 10 measurements of the (131)I content in human thyroids had been performed in May/June 1986. Thyroid doses due to the Chernobyl accident were assessed for the birth years 1968-1985 and related to thyroid cancers that were surgically removed during the period 1990-2001. The central estimate for the linear coefficient of the EAR dose response was 2.66 (95% CI: 2.19; 3.13) cases per 10(4) PY-Gy; for the quadratic coefficient, it was -0.145 (95% CI: -0.171; -0.119) cases per 10(4) PY-Gy(2). The EAR was found to be higher for females than for males by a factor of 1.4. It decreased with age at exposure and increased with age attained. The central estimate for the linear coefficient of the ERR dose response was 18.9 (95% CI: 11.1; 26.7) Gy(-1); for the q...

Journal of Radiological Protection, 1999

The paper presents the analysis of thyroid cancer incidence in the territories of Russia that were most contaminated after the Chernobyl accident. Incidence data in the Bryansk, Kaluga, Orel and Tula regions (5,298 thousand persons) are used. Information on incidence has been obtained from regional oncological dispensaries (state health institutions involved in diagnosis and treatment of malignant neoplasms). Altogether, 2,599 cases of thyroid cancer are considered from 1982 to 1995. Of them, 62 cases were among children and adolescents and 143 among the population who were children and adolescents at the time of the accident in 1986. The study is performed for both sexes. The study compares the distribution of thyroid cancer cases by age at diagnosis and age at exposure. It has been shown that since 1991 the age structure of the incidence has changed significantly with the growing proportion of cases among children and adolescents. The change in the structure occurred due to the radiation factor, specifically as a result of exposure of thyroid to incorporated 131 I. A dependence of risk of cancer on age at exposure has been derived. For children of 0-4 years at exposure the risk of induction of radiogenic thyroid cancer is 6-10 times higher than in adults. On the average, the risk coefficient in children and adolescents at the time of exposure is about 3 times higher than that in adults. The analysis of time trend in thyroid cancer incidence has shown that the incidence rate observed in the period from 1991 to 1995 in the age groups up to 25 years is expected to be maintained in the near future.

International Congress Series, 2007

During 20 years after the Chernobyl catastrophe (1986-2005 inclusive) thyroid cancer was diagnosed in more than 12,000 patients of Belarus. The peak incidence in children was observed in 1995 and since 2001 only sporadic cases occur in the age group under 15 years old. In adolescents, the maximum was registered in 2001. By contrast, in the age group of 46 years or over, the current tendency is a marked increase in the number of primary thyroid cancers that dictates a correspondent intensification of special kinds of treatment. Despite a great number of patients, disease-associated mortality remains stably low; the increasing incidence indicates that thyroid malignancies have proved an actual medical problem in 5 of the 6 administrative regions of Belarus.

2021

This study analyzed the sex and age characteristics of the incidence of thyroid cancer between residents of contaminated and not contaminated by the iodine-131 districts of Belarus in whom thyroid cancer was registered from 1986 to 2016. The analysis was carried out according to the data of the Belarusian Cancer Register and was focused on the age groups of 0-4, 5-9, 10-14, and 15-18 years old as of April 1986, i.e. at the time of the Chernobyl accident. The control group of patients was taken from the Lepel district of the Vitebsk region, which was not contaminated with iodine isotopes . The shortest latency period until the onset of the disease (16 years) was found for the 0-4 years old group. There are no significant gender differences in latency time and the age of diagnosis of thyroid cancer. In general, the incidence rates of thyroid cancer in the Brest region are higher than in the Vitebsk region, where there was practically no radioactive fallout of iodine-131. Comparison of...

Journal of radiological protection : official journal of the Society for Radiological Protection, 2006

Our objective is to assess the regional and temporal dependences of the baseline cases contributing to thyroid cancer incidence among those exposed in childhood or during adolescence in Belarus and Ukraine after the Chernobyl accident. Data are analysed for Kyiv and Sevastopol City and the 25 oblasts (regions) in Ukraine, and for Minsk and Gomel City and the 6 oblasts in Belarus. Average thyroid doses due to the Chernobyl accident were assessed for every birth year in the period from 1968 to 1985. Case data pertain to people who underwent surgical removal of thyroid cancers during the period 1986 to 2001 and who were allocated to their place of residence at the time of the accident. The 35 oblasts/cities were subdivided into an upper, middle and lower group of baseline thyroid cancer incidence. Poisson regressions were performed to estimate age, time and gender dependences of the baseline incidence rates in the three groups. The majority of oblasts/cities with high average doses and...

Radiation Research, 1998

International Congress Series, 2002

The manuscript presents results of the radiogenic thyroid cancer risk analysis in the Bryansk and Oryol regions among children and adolescents at exposure (0-17 years of age). A total of 170 cases of thyroid cancer were diagnosed from 1991 to 1998. Of these, 106 cases were in the Bryansk and 64 in the Oryol region. The size of the exposed population under study is 374 447 persons in the Bryansk region and 207 592 persons in the Oryol region (data of the 1989 census). The mean thyroid dose from incorporated isotopes of 131 I for children and adolescents at exposure is 0.071 Gy in the Bryansk region and 0.013 Gy in the Oryol region. The method of maximum likelihood for nonstationary Poisson series of events was used for risk calculation. The analysis focuses on the relationship between thyroid cancer incidence and thyroid dose due to incorporated iodine radioisotopes. The calculations were based on personal data about disease cases and demographic and dose information for the population points in the regions under study. Statistically significant excess of thyroid cancer incidence above the spontaneous rate was obtained for children and adolescents of the Bryansk region. The excess relative risk per unit dose of 1 Gy (ERR 1Gy) with 95% confidence intervals is 11.9 (7.2, 16.6). For children and adolescents of the Oryol region between 1991 and 1998 statistically significant excess risk was not detected: 6.5 (À20.2, 30.2). The value of the standardized ratio of spontaneous thyroid cancer incidence in the region to the general incidence in Russia is 3.5 with 95% confidence intervals (2.8, 4.2) for the Bryansk region. For the Oryol region this ration is 5.3 (4.0, 6.6). The excess of spontaneous incidence observed in the study areas is primarily due to regional differences in incidence and registration features (screening effect). The attributive risk of induction of radiogenic cancers among children and adolescents in the Bryansk region is 46%. This mean that one of every two thyroid cancers detected in the Bryansk 0531-5131/02

International Congress Series, 2002

In 1996, following several years of collaborative international studies of the consequences of the Chernobyl accident, a number of groups proposed to carry out case -control studies of thyroid cancer among young people in contaminated territories of Belarus and Russia. Collaborations were set-up between the participants of the Chernobyl Sasakawa Project and of those of the Belarus/Russia/EU/ IARC project. These involved joint field work and dose reconstruction, although both projects maintained their original objectives: to evaluate the risk of I-131-induced thyroid cancer and to study the role of possible modifying factors in radiation carcinogenesis, in particular, iodine deficiency and supplementation and genetic predisposition. Joint data collection is now virtually finished and dose reconstruction is nearing completion. Final results are expected in 2002. The current paper summarises the objectives and methods of the case -control studies, as well as the very preliminary 0531-5131/02 D I.; Germany: Goulko G.; Italy: Pacini F., Pinchera A.; Japan: Hoshi M., Ito M., Shibata Y., Yamashita S.; UK: Thomas G., Williams D.; US: Bouville A.; IARC, France: Cardis E., Kesminiene A., Maceika E., Tenet V. International Congress Series 1234 (2002) 105 -113

Radiation and Environmental Biophysics, 1997

The thyroid cancer incidence in the Ukraine among those born in the period 1968-1986 was analyzed with the aim to identify the enhancement due to the Chernobyl accident. Since any Ukrainian data referring to the time period before the accident are scarce and the variation of spontaneous incidences in other countries is immense, the Ukrainian incidences in the period 1986-1989 were used to estimate the baseline risk. Following 1990, the incidence in the southern part of the Ukraine increased by about 30%, independent of age. In the other parts the increase of the incidence depended on age at exposure. In the age group of 9-year-old children, the incidences in three regions defined as the 'high-dose area', the northern, and the middle oblasts, increased by factors of 50, 20, and 6, respectively. These rates (1991)(1992)(1993)(1994)(1995) are well above spontaneous rates in other countries. In the age group of 17-year-old juveniles, the incidence increased by a factor of 6 for the 'high dose area' and in the three northern oblasts, whereas in the nine 'middle' oblasts it was similar to the incidence of the 'southern' Ukraine. These rates are within the range found in other countries.