After large-scale radiation accidents where many individuals are suspected to be exposed to ionizing radiation, biological and physical retrospective dosimetry assays are important tools to aid clinical decision making by categorizing individuals into unexposed/minimally, moderately or highly exposed groups. Quality-controlled inter-laboratory comparisons of simulated accident scenarios are regularly performed in the frame of the European legal association RENEB (Running the European Network of Biological and Physical retrospective Dosimetry) to optimize international networking and emergency readiness in case of large-scale radiation events. In total 33 laboratories from 22 countries around the world participated in the current RENEB inter-laboratory comparison 2021 for the dicentric chromosome assay. Blood was irradiated in vitro with X rays (240 kVp, 13 mA, ∼75 keV, 1 Gy/min) to simulate an acute, homogeneous whole-body exposure. Three blood samples (no. 1: 0 Gy, no. 2: 1.2 Gy, no. 3: 3.5 Gy) were sent to each participant and the task was to culture samples, to prepare slides and to assess radiation doses based on the observed dicentric yields from 50 manually or 150 semi-automatically scored metaphases (triage mode scoring). Approximately two-thirds of the participants applied calibration curves from irradiations with γ rays and about 1/3 from irradiations with X rays with varying energies. The categorization of the samples in clinically relevant groups corresponding to individuals that were unexposed/minimally (0-1 Gy), moderately (1-2 Gy) or highly exposed (>2 Gy) was successfully performed by all participants for sample no. 1 and no. 3 and by ≥74% for sample no. 2. However, while most participants estimated a dose of exactly 0 Gy for the sham-irradiated sample, the precise dose estimates of the samples irradiated with doses >0 Gy were systematically higher than the corresponding reference doses and showed a median deviation of 0.5 Gy (sample no. 2) and 0.95 Gy (sample no. 3) for manual scoring. By converting doses estimated based on γ-ray calibration curves to X-ray doses of a comparable mean photon energy as used in this exercise, the median deviation decreased to 0.27 Gy (sample no. 2) and 0.6 Gy (sample no. 3). The main aim of biological dosimetry in the case of a large-scale event is the categorization of individuals into clinically relevant groups, to aid clinical decision making. This task was successfully performed by all participants for the 0 Gy and 3.5 Gy samples and by 74% (manual scoring) and 80% (semiautomatic scoring) for the 1.2 Gy sample. Due to the accuracy of the dicentric chromosome assay and the high number of participating laboratories, a systematic shift of the dose estimates could be revealed. Differences in radiation quality (X ray vs. γ ray) between the test samples and the applied dose effect curves can partly explain the systematic shift. There might be several additional reasons for the observed bias (e.g., donor effects, transport, experimental conditions or the irradiation setup) and the analysis of these reasons provides great opportunities for future research. The participation of laboratories from countries around the world gave the opportunity to compare the results on an international level.
The goal of the RENEB inter-laboratory comparison 2021 exercise was to simulate a large-scale radiation accident involving a network of biodosimetry labs. Labs were required to perform their analyses using different biodosimetric assays in triage mode scoring and to rapidly report estimated radiation doses to the organizing institution. This article reports the results obtained with the cytokinesis-block micronucleus assay. Three test samples were exposed to blinded doses of 0, 1.2 and 3.5 Gy X-ray doses (240 kVp, 13 mA, ∼75 keV, 1 Gy/min). These doses belong to 3 triage categories of clinical relevance: a low dose category, for no exposure or exposures inferior to 1 Gy, requiring no direct treatment of subjects; a medium dose category, with doses ranging from 1 to 2 Gy, and a high dose category, after exposure to doses higher than 2 Gy, with the two latter requiring increasing medical attention. After irradiation the test samples (no. 1, no. 2 and no. 3) were sent by the organizing laboratory to 14 centers participating in the micronucleus assay exercise. Laboratories were asked to setup micronucleus cultures and to perform the micronucleus assay in triage mode, scoring 500 binucleated cells manually, or 1,000 binucleated cells in automated/semi-automated mode. One laboratory received no blood samples, but scored pictures from another lab. Based on their calibration curves, laboratories had to provide estimates of the administered doses. The accuracy of the reported dose estimates was further analyzed by the micronucleus assay lead. The micronucleus assay allowed classification of samples in the corresponding clinical triage categories (low, medium, high dose category) in 88% of cases (manual scoring, 88%; semi-automated scoring, 100%; automated scoring, 73%). Agreement between scoring laboratories, assessed by calculating the Fleiss' kappa, was excellent (100%) for semi-automated scoring, good (83%) for manual scoring and poor (53%) for fully automated scoring. Correct classification into triage scoring dose intervals (reference dose ±0.5 Gy for doses ≤2.5 Gy, or reference dose ±1 Gy for doses >2.5 Gy), recommended for triage biodosimetry, was obtained in 79% of cases (manual scoring, 73%; semi-automated scoring, 100%; automated scoring, 67%). The percentage of dose estimates whose 95% confidence intervals included the reference dose was 58% (manual scoring, 48%; semiautomated scoring, 72%; automated scoring, 60%). For the irradiated samples no. 2 and no. 3, a systematic shift towards higher dose estimations was observed. This was also noticed with the other cytogenetic assays in this intercomparison exercise. Accuracy of the rapid triage modality could be maintained when the number of manually scored cells was scaled down to 200 binucleated cells. In conclusion, the micronucleus assay, preferably performed in a semi-automated or manual scoring mode, is a reliable technique to perform rapid biodosimetry analysis in large-scale radiation emergencies.
- MeSH
- hojení ran účinky záření MeSH
- kontraindikace MeSH
- kůže účinky záření MeSH
- lidé MeSH
- obvazy klasifikace MeSH
- radiační poranění * etiologie farmakoterapie klasifikace MeSH
- radioterapie škodlivé účinky MeSH
- sloučeniny stříbra * terapeutické užití MeSH
- vztah dávky záření a odpovědi MeSH
- Check Tag
- lidé MeSH
Východiska: Vliv ionizujícího záření indikovaného k léčbě zhoubných nádorů na imunitní systém zůstával dlouho stranou hlavního zájmu. Problematika v současnosti nabývá na významu, zejména v souvislosti s rozvojem a dostupností imunoterapeutické léčby. Radioterapie je v léčbě nádorových onemocnění schopna ovlivnit imunogenicitu nádoru zvýšením exprese některých antigenů specifických pro nádor. Tyto antigeny mohou být zpracovány imunitním systémem a stimulovat naivní lymfocyty k přeměně na tumor specifické lymfocyty. Lymfocytární populace je zároveň mimořádně citlivá na nízké dávky ionizujícího záření a radioterapie často indukuje těžkou lymfopenii. Závažná lymfopenie je negativním prognostickým faktorem řady nádorových onemocnění a negativně ovlivňuje i účinnost následné imunoterapeutické léčby. Cíl: V článku shrnujeme možné ovlivnění imunitního systému radioterapií s důrazem na ovlivnění cirkulujících imunitních buněk zářením a důsledky tohoto ovlivnění pro vývoj nádorového onemocnění. Závěr: Lymfopenie je významným faktorem ovlivňujícím výsledky onkologické léčby a její výskyt je při radioterapii častý. Strategie redukující riziko lymfopenie spočívají v akceleraci léčebných režimů, redukci cílových objemů, zkracování beam-on time ozařovačů, v optimalizaci radioterapie na nové kritické orgány, použití částicové radioterapie a v dalších postupech redukujících integrální dávku záření.
Background: The effect of ionizing radiation on the immune system during the treatment of malignant tumors has long remained a point of great interest. This issue is currently gaining importance, especially in connection with the advancing development and availability of immunotherapeutic treatment. During cancer treatment, radiotherapy has the ability to influence the immunogenicity of the tumor by increasing the expression of certain tumor-specific antigens. These antigens can be processed by the immune system, stimulating the transformation of na?ve lymphocytes into tumor-specific lymphocytes. However, at the same time, the lymphocyte population is extremely sensitive to even low doses of ionizing radiation, and radiotherapy often induces severe lymphopenia. Severe lymphopenia is a negative prognostic factor for numerous cancer diagnoses and negatively impacts the effectiveness of immunotherapeutic treatment. Aim: In this article, we summarize the possible influence of radiotherapy on the immune system, with a particular emphasis on the impact of radiation on circulating immune cells and the subsequent consequences of this influence on the development of cancer. Conclusion: Lymphopenia is an important factor influencing the results of oncological treatment, with a common occurrence during radiotherapy. Strategies to reduce the risk of lymphopenia consist of accelerating treatment regimens, reducing target volumes, shortening the beam-on time of irradiators, optimizing radiotherapy for new critical organs, using particle radiotherapy, and other procedures that reduce the integral dose of radiation.
- Klíčová slova
- protinádorová imunitní reakce,
- MeSH
- lidé MeSH
- lymfopenie * etiologie MeSH
- radioterapie škodlivé účinky MeSH
- tolerance záření MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
The JC-1 dye is widely used in apoptosis studies to monitor mitochondrial health. The probe was tested in vitro on two established cell lines and peripheral porcine blood lymphocytes after gamma irradiation (IR) to assess its potential in biodosimetric evaluation. In brief, we stained irradiated and non-irradiated cells with the JC-1 dye to determine the existing changes in mitochondrial membrane potential and monitor cell health through flow cytometry. The stage of injury in these cells was evaluated through an irradiated versus non-irradiated ratio (IVNIR), comparing the relative proportion of polarised cells containing red JC-1 aggregates. We observed a decreasing IVNIR as the radiation dose increased (i.e. 0.5; 1; 2; 4; 6; 8 and 10 Gy), performing the analysis at 4, 8 and 24 h after IR in all the tested cells. The results from the JC1-dye test showed that CD4 T lymphocytes were more sensitive to irradiation than other subpopulations.
This study establishes a new experimental approach for retrospective biodosimetric assessment by apoptosis detection ex vivo. For this purpose, we used mononuclear blood leukocytes isolated from the peripheral blood of irradiated Wistar rats and cultured them ex vivo for posterior analysis. Using flow cytometry, we distinguished apoptotic lymphocyte subsets individual biodosimetric potential at different time periods after exposure: B-lymphocytes 6-8 h (0-7 Gy), natural killer cells 24 h (0-7 Gy) and T-lymphocytes 24 h (0-1 Gy). This novel experimental design innovates through the need of a single blood sample from irradiated individuals for a complete biodosimetric assessment.
Východiska: Poškození DNA ionizujícím zářením je hlavním mechanizmem účinku radioterapie (RT) a výsledek léčby a poradiační toxicitu zdravých tkání ovlivňuje řada faktorů zevních a vnitřních, mezi které patří i mutace v genech pro reparaci DNA vedoucí k různým poruchám rozpoznávání poškozené DNA a jejich oprav. Poruchy reparace DNA se mohou projevovat zvýšenou citlivostí k onkologické léčbě. Cíl: Mechanizmus opravy DNA a přehled genetických syndromů s mutacemi genů účastnících se reparace DNA objasňuje urychlenou kancerogenezi a zvýšenou radiosenzitivitu při RT nádorových onemocnění. Většina radiosenzitivních syndromů je autozomálně recesivně dědičná, příkladem jsou ataxia teleangiectasia, Nijmegenský syndrom lomivosti, xeroderma pigmentosum, Cockaynův syndrom, Bloomův syndrom a Wernerův syndrom. Závěr: Radioterapie je u většiny homozygotních pacientů s recesivními radiosenzitivními syndromy kontraindikována. Asymptomatičtí heterozygoti mohou mít zvýšené riziko vzniku nádorů a malá část pacientů i mírně zvýšené riziko intolerance RT, nicméně indikaci k RT to nelimituje. Vysoké riziko sekundárních malignit po radioterapii je kontraindikací adjuvantní RT u Li-Fraumeniho syndromu.
Background: Ionizing radiation DNA damage is the main mechanism of radiotherapy (RT) action and the outcome of treatment and healthy tissue toxicity is influenced by a number of external and internal factors, including mutations in DNA damage recognition and repair. Disorders of DNA repair may result in increased sensitivity to cancer treatment. Purpose: The mechanism of DNA repair and an overview of genetic syndromes with mutations in genes involved in DNA repair clarify the accelerated carcinogenesis and increased radiosensitivity in RT cancers. Most radiosensitivity syndromes are autosomal recessively inherited; examples are ataxia teleangiectasia, Nijmegen breakage syndrome, xeroderma pigmentosum, Cockayne syndrome, Bloom syndrome and Werner syndrome. Conclusion: Radiotherapy is contraindicated in most homozygous patients with recessive radiosensitivity syndromes. Asymptomatic heterozygotes may have an increased risk of tumor incidence and a small part of them slightly increased risk of RT intolerance; however, this does not limit RT treatment. The high risk of secondary malignancies after radiotherapy is a contraindication to adjuvant RT in Li-Fraumeni syndrome.
- MeSH
- Cockayneův syndrom genetika MeSH
- lidé MeSH
- mutace MeSH
- oprava DNA genetika MeSH
- tolerance záření * genetika MeSH
- xeroderma pigmentosum genetika MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
PURPOSE: The complex relationship between linear energy transfer (LET) and cellular response to radiation is not yet fully elucidated. To better characterize DNA damage after irradiations with therapeutic protons, we monitored formation and disappearance of DNA double-strand breaks (DNA DSB) as a function of LET and time. Comparisons with conventional γ-rays and high LET carbon ions were also performed. MATERIALS AND METHODS: In the present work, we performed immunofluorescence-based assay to determine the amount of DNA DSB induced by different LET values along the 62 MeV therapeutic proton Spread out Bragg peak (SOBP) in three cancer cell lines, i.e. HTB140 melanoma, MCF-7 breast adenocarcinoma and HTB177 non-small lung cancer cells. Time dependence of foci formation was followed as well. To determine irradiation positions, corresponding to the desired LET values, numerical simulations were carried out using Geant4 toolkit. We compared γ-H2AX foci persistence after irradiations with protons to that of γ-rays and carbon ions. RESULTS: With the rise of LET values along the therapeutic proton SOBP, the increase of γ-H2AX foci number is detected in the three cell lines up to the distal end of the SOBP, while there is a decrease on its distal fall-off part. With the prolonged incubation time, the number of foci gradually drops tending to attain the residual level. For the maximum number of DNA DSB, irradiation with protons attain higher level than that of γ-rays. Carbon ions produce more DNA DSB than protons but not substantially. The number of residual foci produced by γ-rays is significantly lower than that of protons and particularly carbon ions. Carbon ions do not produce considerably higher number of foci than protons, as it could be expected due to their physical properties. CONCLUSIONS: In situ visualization of γ-H2AX foci reveal creation of more lesions in the three cell lines by clinically relevant proton SOBP than γ-rays. The lack of significant differences in the number of γ-H2AX foci between the proton and carbon ion-irradiated samples suggests an increased complexity of DNA lesions and slower repair kinetics after carbon ions compared to protons. For all three irradiation types, there is no major difference between the three cell lines shortly after irradiations, while later on, the formation of residual foci starts to express the inherent nature of tested cells, therefore increasing discrepancy between them.
- MeSH
- dvouřetězcové zlomy DNA účinky záření MeSH
- lidé MeSH
- lineární přenos energie * MeSH
- nádorové buněčné linie MeSH
- oprava DNA účinky záření MeSH
- protony * MeSH
- relativní biologická účinnost MeSH
- viabilita buněk účinky záření MeSH
- vztah dávky záření a odpovědi MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In breast cancer radiotherapy, substantial radiation exposure of organs other than the treated breast cannot be avoided, potentially inducing second primary cancer or heart disease. While distant organs and large parts of nearby ones receive doses in the mGy-Gy range, small parts of the heart, lung and bone marrow often receive doses as high as 50 Gy. Contemporary treatment planning allows for considerable flexibility in the distribution of this exposure. To optimise treatment with regards to long-term health risks, evidence-based risk estimates are required for the entire broad range of exposures. Here, we thus propose an approach that combines data from medical and epidemiological studies with different exposure conditions. Approximating cancer induction as a local process, we estimate organ cancer risks by integrating organ-specific dose-response relationships over the organ dose distributions. For highly exposed organ parts, specific high-dose risk models based on studies with medical exposure are applied. For organs or their parts receiving relatively low doses, established dose-response models based on radiation-epidemiological data are used. Joining the models in the intermediate dose range leads to a combined, in general non-linear, dose response supported by data over the whole relevant dose range. For heart diseases, a linear model consistent with high- and low-dose studies is presented. The resulting estimates of long-term health risks are largely compatible with rate ratios observed in randomised breast cancer radiotherapy trials. The risk models have been implemented in a software tool PASSOS that estimates long-term risks for individual breast cancer patients.
- MeSH
- hodnocení rizik MeSH
- kouření MeSH
- leukemie MeSH
- lidé MeSH
- nádory plic MeSH
- nádory prsu radioterapie MeSH
- nemoci srdce MeSH
- software MeSH
- teoretické modely * MeSH
- vztah dávky záření a odpovědi MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- kombinovaná terapie MeSH
- konformní radioterapie metody MeSH
- lidé MeSH
- nádory * farmakoterapie radioterapie MeSH
- protinádorové látky imunologicky aktivní terapeutické užití MeSH
- vztah dávky záření a odpovědi MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- komentáře MeSH
- souhrny MeSH
