Non-cancer effects in acute radiation syndrome survivors in Ukraine.

The 1986 Chernobyl Nuclear Power Plant accident that occurred is known as the most severe nuclear disaster in the history of humankind. Acute radiation syndrome (ARS) was diagnosed in 237 persons but only 134 of those were confirmed, including 28 patients who died due to lethal total-body gamma-irradiation and severe skin injuries caused by beta/gamma-emitting radionuclides. A small group of ARS survivors offers an interesting observational insight pertinent to the on-going discussions about long-term non-cancer effects of ionizing radiation. This descriptive study summarizes more than 20 y of follow-up, makes attempts to offer a prognosis for the Chernobyl ARS survivors' health, and explores the link between the outcomes of interest and radiation exposure.

Chronic lymphocytic leukemia patients exposed to ionizing radiation due to the Chernobyl NPP accident--with focus on immunoglobulin heavy chain gene analysis.

Clinical data and immunoglobulin variable heavy chain (IgVH) gene configuration were analyzed in 47 CLL patients, exposed to ionizing radiation (IR) due to Chernobyl NPP accident, and 141 non-exposed patients. Clean-up workers of the second quarter of 1986 (n=19) were picked out as separate group with the highest number of unmutated cases (94.4%), increased usage of IgVH1-69 (33.3%) and IgVH3-21 (16.7%) genes, high frequency of secondary solid tumors (6 cases) and Richter transformation (4 cases). These preliminary data suggest that CLL in the most suffered contingent due to Chernobyl NPP accident might have some specific features.

Cancer consequences of the Chernobyl accident: 20 years on.

26 April 2006 marks the 20th anniversary of the Chernobyl accident. On this occasion, the World Health Organization (WHO), within the UN Chernobyl Forum initiative, convened an Expert Group to evaluate the health impacts of Chernobyl. This paper summarises the findings relating to cancer. A dramatic increase in the incidence of thyroid cancer has been observed among those exposed to radioactive iodines in childhood and adolescence in the most contaminated territories. Iodine deficiency may have increased the risk of developing thyroid cancer following exposure to radioactive iodines, while prolonged stable iodine supplementation in the years after exposure may reduce this risk. Although increases in rates of other cancers have been reported, much of these increases appear to be due to other factors, including improvements in registration, reporting and diagnosis. Studies are few, however, and have methodological limitations. Further, because most radiation-related solid cancers continue to occur decades after exposure and because only 20 years have passed since the accident, it is too early to evaluate the full radiological impact of the accident. Apart from the large increase in thyroid cancer incidence in young people, there are at present no clearly demonstrated radiation-related increases in cancer risk. This should not, however, be interpreted to mean that no increase has in fact occurred: based on the experience of other populations exposed to ionising radiation, a small increase in the relative risk of cancer is expected, even at the low to moderate doses received. Although it is expected that epidemiological studies will have difficulty identifying such a risk, it may nevertheless translate into a substantial number of radiation-related cancer cases in the future, given the very large number of individuals exposed.

Aml1 gene rearrangements and mutations in radiation-associated acute myeloid leukemia and myelodysplastic syndromes.

Several studies suggested a causal link between AML1 gene rearrangements and both radiation-induced acute myeloid leukaemia (AML) and myelodysplastic syndromes (MDS). Fifty-three AML samples were analyzed for the presence of AML1 abnormalities using fluorescent in-situ hybridization (FISH) and reverse transcription polymerase chain reaction (RT-PCR). Of these patients, 24 had experienced radiation exposure due to the Chernobyl accident, and 29 were non-irradiated spontaneous AML cases and served as controls. AML1/ETO translocations were found in 9 of 29 spontaneous AML but only in 1 of 24 radiation-associated AML cases. This difference between translocation frequencies is statistically significant in the age-unstratified cohorts (p=0.015). Following age stratification, the difference becomes less pronounced but remains on borderline significance (p=0.053). AML1 mutation status was assessed in 5 clean-up workers at Chernobyl NPP with MDS, or AML following MDS, by direct sequencing of genomic DNA from the coding region (exon 3 through 8). In one patient who developed MDS following an acute radiation syndrome, a hexanucleotide duplication of CGGCAT in exon 8 was found, inserted after base position 1502. Our results suggest that AML1 gene translocations are infrequent in radiation-induced leukemogenesis but are consistent with the idea that radiation may contribute to the development of MDS through AML1 gene mutation.

MLL gene alterations in radiation-associated acute myeloid leukemia.

AIM: Although acute myelogenous leukemia (AML) arising after radiation exposure is considered to be secondary, little is known about the molecular mechanisms by which the radiation induces the leukemogenic phenotype. The aim of the study was to analyze whether the MLL translocations are as frequent in radiation-associated AML as in spontaneous AML cases. METHODS: Sixty one AML samples obtained at diagnosis were analyzed for the presence of MLL abnormalities using fluorescent in situ hybridization and/or reverse transcription polymerase chain reaction. Of these patients, 27 had experienced radiation exposure due to the Chernobyl accident, 32 were non-irradiated (spontaneous AML), and 2 developed therapy-related AML after chemotherapy with topoisomerase II inhibitors. RESULTS: MLL gene translocations were detected in both groups of spontaneous and therapy-related AML (1/32 and 1/2 cases respectively). The sole MLL rearrangement found in the group of radiation-associated AML patients was a duplication of the gene. CONCLUSION: Our data preclude the involvement of MLL gene translocations in radiation-induced leukemogenesis, but support the assumption that loss and gain of chromosomal material could be crucial in the leukemogenesis of AML patients with the history of radiation exposure due to the Chernobyl accident.

Delayed effects of accidental cutaneous radiation exposure: fifteen years of follow-up after the Chernobyl accident.

BACKGROUND: During the Chernobyl accident in 1986, 237 individuals were identified as having the most severe exposure to ionizing radiation. In the period between 1998 and 2000, 99 long term survivors out of this group were reassessed for radiation-induced cutaneous lesions. OBJECTIVE: To identify sequelae of accidental cutaneous irradiation. METHODS: Detailed dermatologic examinations, including biopsies of suspicious cutaneous lesions for histopathologic examination and 20 MHz sonography, were performed in all patients. RESULTS: Twenty-two of the 99 patients displayed radiation-induced cutaneous lesions. Epidermal atrophy, telangiectases, and pigment alterations were present in all these individuals. Keratotic lesions were found in 14 patients. Cutaneous fibrosis was documented in 8 individuals by the use of 20 MHz sonography, while a radiation ulcer was found in 5. In one patient, two basal cell carcinomas were found. CONCLUSION: The life-long follow-up of irradiated persons is of great importance in order to identify cutaneous neoplasms at an early treatable stage.

Chernobyl disaster : Promotion of follow-up studies

Problem of clinically observed effects of irradiation and other damaging agents of Chernobyl accident is analysed in connection with the previous data. Several international and national scientific programs were performed during the 10 years after the accident. Obtained data are extremely useful for the elaboration of the system of radiation emergency medical preparedness and assistance network in Europe. Difficulties in diagnostic, therapeutic and statistical evaluation measures were characteristic for the first years after the accident. Future perspectives must include scientific investigation and practical help for the main groups of irradiated population on the international basis with the wide access to obtained data for the international community. The analysis of the materials and the circumstances under which they have been received are the basis for determining the following stages in learning the factors of the CPPA influence upon the health conditions of the exposed population: stage 1: 1986; stage 2: 1991; stage 3: 1993-1997. During 1986-1990 the investigations were carried out under the circumstances of the USSR within the framework of the Union programmes while special medical centres of the Union subordination, located in Moscow, took part in them. The major part of these investigations had been classified till 1989. The document presents as a result of the studies of early and middle-term effects some scientific knowledge obtained