Increase of regional total cancer incidence in north Sweden due to the Chernobyl accident?
STUDY OBJECTIVE: Is there any epidemiologically visible influence on the cancer incidence after the Chernobyl fallout in Sweden? DESIGN: A cohort study was focused on the fallout of caesium-137 in relation to cancer incidence 1988-1996. SETTING: In northern Sweden, affected by the Chernobyl accident in 1986, 450 parishes were categorised by caesium-137 deposition: < 3 (reference), 3-29, 30-39, 40-59, 60-79, and 80-120 kiloBecquerel/m(2). PARTICIPANTS: All people 0-60 years living in these parishes in 1986 to 1987 were identified and enrolled in a cohort of 1 143 182 persons. In the follow up 22 409 incident cancer cases were retrieved in 1988-1996. A further analysis focused on the secular trend. MAIN RESULTS: Taking age and population density as confounding factors, and lung cancer incidence in 1988-1996 and total cancer incidence in 1986-1987 by municipality as proxy confounders for smoking and time trends, respectively, the adjusted relative risks for the deposition categories were 1.00 (reference < 3 kiloBecquerel/m(2)), 1.05, 1.03, 1.08, 1.10, and 1.21. The excess relative risk was 0.11 per 100 kiloBecquerel/m(2) (95% CI 0.03 to 0.20). Considering the secular trend, directly age standardised cancer incidence rate differences per 100 000 person years between 1988 to 1996 and the reference period 1986-1987, were 30.3 (indicating a time trend in the reference category), 36.8, 42.0, 45.8, 50.1, and 56.4. No clear excess occurred for leukaemia or thyroid cancer. CONCLUSIONS: Unless attributable to chance or remaining uncontrolled confounding, a slight exposure related increase in total cancer incidence has occurred in northern Sweden after the Chernobyl accident. (+info)
Thyroid disease in northern Italian children born around the time of the Chernobyl nuclear accident.
BACKGROUND: The Chernobyl nuclear accident of 1986 caused a dramatic increase in the incidence of thyroid cancers in exposed children in Belarus. Airborne radioactivity from the reactor spread over northern Italy, where rainout gave rise to low levels of radioactivity at ground level. PATIENTS AND METHODS: As the latency between exposure to ionising radiation and development of thyroid cancer is thought to be about 10 years, in 1996/1997 all children born in 1985 and 1986 and attending school in an area of Milan, Italy were examined for thyroid nodules. A total of 3949 children were examined by two physicians blinded to the examination and diagnosis of the other. The children were to be reassessed in 2001/2002. RESULTS: In total, 1% had palpable nodules. The nodule diagnoses were: Hurtle cell adenoma (one), thyroglossal duct cyst (one), thyroid cyst (four) and thyroiditis (four). The prevalence of thyroid disease in the cohort was indistinguishable from that of populations not exposed to radioactive pollution. Only 10 children re-presented for examination 5 years later; all were negative. The direct costs of the study were estimated at 21,200 Euros. CONCLUSION: The high cost of the study in relation to reassuring lack of increase in thyroid nodule prevalence suggests that further studies are not justified. (+info)
National cancer registry to assess trends after the Chernobyl accident.
The National Cancer Registry has been operational in the Republic of Belarus since 1973: information on all new cases of malignant tumours is registered. The data are kept in a computer database and used for assessing the oncological status of the population, and for epidemiological studies. We compared findings before the Chernobyl accident of April 26, 1986 (Chernobyl) and findings between 1990 and 2000. The overall comparison on the changes in the incidence of cancer morbidity in Belarus is presented. The increase is statistically significant for all regions, but significantly greater in the most chronically radiation-contaminated region: the Gomel oblast. The paper presents a comparative analysis of the incidence of cancer morbidity in the population of two regions of Belarus, selected for the greatest difference in their radioactive contamination following Chernobyl. The highest contamination occurred in the Gomel region and is mainly due to high levels of radiocaesium (137Cs) in the soil and in the alimentary chain, especially in rural areas. A relatively low radioactive fallout was noticed in the Vitebsk region, considered here as the "control" area. We compare the situation before and after Chernobyl in the two regions. The overall cancer morbidity rate in all organs including colon, urinary bladder and thyroid, was significantly higher in the Gomel region than in Vitebsk. In populations living in two areas with high 137Cs contamination (oblast of Gomel and Mogilev), the peak incidence rates of breast cancer were already reached between the ages of 45-49 years, 15 years earlier than in the Vitebsk region. Belarussian "liquidators" who were mobilised to clean up the most contaminated territory and build the sarcophagus around the destroyed atomic plant, received the highest radiation doses. They had a significant excess of incidence of cancers of colon, urinary bladder, and thyroid gland, when compared with a corresponding adult population of the Vitebsk region. The Relative Risk (RR) of lung cancer among "liquidators" in 1997-2000 significantly exceeded 1, while in the control population it remained stable. (+info)
Longitudinal neurocognitive assessments of Ukrainians exposed to ionizing radiation after the Chernobyl nuclear accident.
A 4-year longitudinal study of the cognitive effects of the Chernobyl nuclear accident was conducted from 1995 to 1998. The controls were healthy Ukrainians residing several hundred kilometers away from Chernobyl. The exposed groups included Eliminators, Forestry workers and Agricultural workers living within 150 km of Chernobyl. Accuracy and efficiency of cognitive performance were assessed using ANAMUKR, a specialized subset of the Automated Neuropsychological Assessment Metrics (ANAM) battery of tests. Analyses of variance, followed by appropriate pairwise comparisons, indicated that the 4-year averaged levels of performance of the exposure groups (especially the Eliminators) were significantly lower than those of the controls on most measures; further, analyses of performance across time revealed significant declines in accuracy and efficiency, as well as psychomotor slowing, for all exposed groups over the 4-year period. These findings strongly indicate impairment of brain function resulting from both acute and chronic exposure to ionizing radiation. (+info)
A new mechanism of BRAF activation in human thyroid papillary carcinomas.
In this issue of the JCI, Ciampi et al. report the identification of a novel oncogene in patients affected by radiation-associated thyroid papillary carcinomas. This oncogene derives from a paracentric inversion of the long arm of chromosome 7, which results in an in-frame fusion of the N-terminus of the A-kinase anchor protein 9 (AKAP9) gene with the C-terminal catalytic domain (exons 9-18) of the serine-threonine kinase BRAF. The resulting AKAP9-BRAF fusion protein shows constitutive kinase activity, and it is able to transmit mitogenic signals to the MAPK pathways and to promote malignant transformation of NIH3T3 cells. (+info)
Oncogenic AKAP9-BRAF fusion is a novel mechanism of MAPK pathway activation in thyroid cancer.
Genes crucial for cancer development can be mutated via various mechanisms, which may reflect the nature of the mutagen. In thyroid papillary carcinomas, mutations of genes coding for effectors along the MAPK pathway are central for transformation. BRAF point mutation is most common in sporadic tumors. By contrast, radiation-induced tumors are associated with paracentric inversions activating the receptor tyrosine kinases RET and NTRK1. We report here a rearrangement of BRAF via paracentric inversion of chromosome 7q resulting in an in-frame fusion between exons 1-8 of the AKAP9 gene and exons 9-18 of BRAF. The fusion protein contains the protein kinase domain and lacks the autoinhibitory N-terminal portion of BRAF. It has elevated kinase activity and transforms NIH3T3 cells, which provides evidence, for the first time to our knowledge, of in vivo activation of an intracellular effector along the MAPK pathway by recombination. The AKAP9-BRAF fusion was preferentially found in radiation-induced papillary carcinomas developing after a short latency, whereas BRAF point mutations were absent in this group. These data indicate that in thyroid cancer, radiation activates components of the MAPK pathway primarily through chromosomal paracentric inversions, whereas in sporadic forms of the disease, effectors along the same pathway are activated predominantly by point mutations. (+info)
Relationship between caesium (137Cs) load, cardiovascular symptoms, and source of food in 'Chernobyl' children -- preliminary observations after intake of oral apple pectin.
Seventeen years after the nuclear power accident at Chernobyl, most of the radio-contamination among the population of Southern Belarus is caused by incorporation of long-lived radioisotopes. The varying levels of 137Cs observed among children in this area are explained by the source of their food, especially by the consumption of contaminated milk produced privately. We stratified children from rural areas of Belarus (caesium [137Cs] contamination >5 Ci/km(2)) by their 137Cs loads into three distinct groups (group 1, <5 Bq/kg body weight [BW]; group 2, 38.4 +/- 2.4 Bq/kg BW; group 3, 122 +/- 18.5 Bq/kg BW). We determined the relationship between the 137Cs load and the children's main source of food and recorded their cardiovascular symptoms. Cardiovascular symptoms, ECG alterations, and arterial hypertension were significantly more frequent in children with high 137Cs burden than in children with very low 137Cs burden. Children with moderate and high 137Cs loads (groups 2 and 3) received apple pectin, a food additive, for 16 days. Apple pectin significantly decreased 137Cs loads in these groups (39% and 28%, respectively). ECG alterations improved, while cardiovascular symptoms and hypertension did not change in any group. (+info)
Sensitivity analysis for trend tests: application to the risk of radiation exposure.
Trend tests are used to assess the relationship between multiple level treatment X and binary response R. In observational studies, however, there may be a confounder U that is associated with treatment X and causally related to response R. When the data for the confounder U are not observed, an approach for assessing the sensitivity of test results to U is provided. Its use is illustrated by examining data from a study of mutation rate after the Chernobyl accident. (+info)