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Abstract
Supplemental Digital Content is available in the text. Background: Studies investigating the population-mixing hypothesis in childhood leukemia principally use two analytical approaches: (1) nonrandom selection of areas according to specific characteristics, followed by comparisons of their incidence of childhood leukemia with that expected based on the national average; and (2) regression analyses of region-wide data to identify characteristics associated with the incidence of childhood leukemia. These approaches have generated contradictory results. We compare these approaches using observed and simulated data. Methods: We generated 10,000 simulated regions using the correlation structure and distributions from a United Kingdom dataset. We simulated cases using a Poisson distribution with the incidence rate set to the national average assuming the null hypothesis that only population size drives the number of cases. Selection of areas within each simulated region was based on characteristics considered responsible for elevated infection rates (population density and inward migration) and/or elevated leukemia rates. We calculated effect estimates for 10,000 simulations and compared results to corresponding observed data analyses. Results: When the selection of areas for analysis is based on apparent clusters of childhood leukemia, biased assessments occur; the estimated 5-year incidence of childhood leukemia ranged between zero and eight per 10,000 children in contrast to the simulated two cases per 10,000 children, similar to the observed data. Performing analyses on region-wide data avoids these biases. Conclusions: Studies using nonrandom selection to investigate the association between childhood leukemia and population mixing are likely to have generated biased findings. Future studies can avoid such bias using a region-wide analytical strategy. See video abstract at, http://links.lww.com/EDE/B431.
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Can changes in population mixing and socio-economic deprivation in Cumbria, England explain changes in cancer incidence around Sellafield? Spat Spatiotemporal Epidemiol 2017; 21:25-36. [PMID: 28552185 DOI: 10.1016/j.sste.2017.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 02/14/2017] [Accepted: 02/21/2017] [Indexed: 11/23/2022]
Abstract
Previously excesses in incident cases of leukaemia and non-Hodgkin lymphoma have been observed amongst young people born or resident in Seascale, Cumbria. These excesses have not been seen more recently. It is postulated that the former apparent increased risk was related to 'unusual population mixing', which is not present in recent years. This study investigated changes in measures of population mixing from 1951-2001. Comparisons were made between three specified areas. Area-based measures were calculated (migration, commuting, deprivation, population density). All areas have become more affluent, although Seascale was consistently the most affluent. Seascale has become less densely populated, with less migration into the ward and less diversity with respect to migrants' origin. There have been marked changes in patterns of population mixing throughout Cumbria. Lesser population mixing has been observed in Seascale in recent decades. Changes in pattern and nature of population mixing may explain the lack of recent excesses.
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Lupatsch JE, Kreis C, Zwahlen M, Niggli F, Ammann RA, Kuehni CE, Spycher BD. Temporal association between childhood leukaemia and population growth in Swiss municipalities. Eur J Epidemiol 2016; 31:763-74. [DOI: 10.1007/s10654-016-0162-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 05/12/2016] [Indexed: 02/05/2023]
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4
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Residential mobility and the risk of childhood leukemia. Cancer Causes Control 2016; 27:433-43. [DOI: 10.1007/s10552-016-0720-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 01/12/2016] [Indexed: 10/22/2022]
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5
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Population mixing and the risk of childhood leukaemia in Switzerland: a census-based cohort study. Eur J Epidemiol 2015; 30:1287-98. [DOI: 10.1007/s10654-015-0042-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 05/12/2015] [Indexed: 10/23/2022]
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6
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Collignon A, Duchenet V, Mouchel D, Malet M, Cornet E, Troussard X. Épidémiologie des hémopathies malignes en Basse-Normandie : incidence et caractéristiques cliniques et biologiques chez l’enfant et l’adulte jeune de moins de 25ans (1997–2005). Rev Epidemiol Sante Publique 2012; 60:343-53. [DOI: 10.1016/j.respe.2012.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 02/10/2012] [Accepted: 03/12/2012] [Indexed: 11/25/2022] Open
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7
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Kinlen LJ. An examination, with a meta-analysis, of studies of childhood leukaemia in relation to population mixing. Br J Cancer 2012; 107:1163-8. [PMID: 22955857 PMCID: PMC3461174 DOI: 10.1038/bjc.2012.402] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Background: Marked influxes of people into rural areas, termed rural population mixing (PM), have been associated with excesses of childhood leukaemia (CL), consistent with mini-epidemics of a mainly immunising, subclinical infection to which CL is a rare response. For such situations of rural PM would promote contacts between infected and susceptible individuals, the latter tending to have a higher than average prevalence in rural or isolated areas. Confusion has arisen from some workers applying the term PM to non-rural situations lacking known recent change. Methods: Available PM studies using the original definition of influxes were examined, a meta-analysis carried out of studies of CL in relation to exposure to high levels of rural PM, and also a detailed analysis by age group. Results: The meta-analysis of 17 studies shows a significant CL excess in association with rural PM: overall relative risk (RR) at ages 0–14: 1.57; 95% confidence interval 1.44–1.72; at 0–4 years 1.72 (1.54–1.91). This contrasts with the absence of an excess of CL in similarly exposed urban areas (RR 1.00; 0.93–1.07), pointing to a high level of immunity there. The mixed results of studies using other definitions of PM were summarised. The excess associated with rural PM below age 2 years (RR 1.51; 1.17, 1.92) was not appreciably different from that at later childhood ages. Conclusion: Much of the inconsistency among studies ostensibly about CL and PM reflects the use of definitions other than that originally proposed. The broad similarity of the CL excess below age 2 with that at older childhood ages is inconsistent with the Greaves’ delayed infection hypothesis, since any infection underlying the former is difficult to consider as delayed.
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Affiliation(s)
- L J Kinlen
- Cancer Epidemiology Unit, University of Oxford, Richard Doll Building, Headington, Oxford OX3 7LF, UK.
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8
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Abstract
The excess of childhood leukaemia (CL) in Seascale, near the Sellafield nuclear reprocessing site in rural NW England, suggested that an epidemic of an underlying infection, to which CL is a rare response, is promoted by marked population mixing (PM) in rural areas, in which the prevalence of susceptibles is higher than average. This hypothesis has been confirmed by 12 studies in non-radiation situations. Of the five established CL excesses near nuclear sites, four are associated with significant PM; in the fifth, the Krummel power station in Germany, the subject has not been thoroughly investigated.
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Affiliation(s)
- L Kinlen
- Cancer Epidemiology Unit, University of Oxford, Richard Doll Building, Headington, Oxford, OX3 7LF, UK.
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9
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Childhood leukaemia in the vicinity of German nuclear power plants - some missing links. J Appl Biomed 2010. [DOI: 10.2478/v10136-009-0010-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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10
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11
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Abstract
This review considers recent studies regarding the role of environmental factors in the etiology of childhood leukemia and lymphoma. Potential environmental risk factors identified for childhood leukemia include exposure to magnetic fields of more than 0.4 micro Tessla, exposure to pesticides, solvents, benzene and other hydrocarbons, maternal alcohol consumption (but only for certain genotypes), contaminated drinking water, infections, and high birth weight. The finding of space-time clustering and seasonal variation also supports a role for infections. There is little evidence linking childhood leukemia with lifetime exposure to ionizing radiation although fetal exposures to X-rays are associated with increased risk. Breast-feeding, consumption of fresh fruit and vegetables and having allergies all appear to be protective. Burkitt lymphoma (BL) is confined to areas of the world where malaria is endemic, with the additional involvement of the Epstein-Barr virus (EBV) as a co-factor. Environmental risk factors suggested for other types of non-Hodgkin lymphoma (NHL) include exposure to ionizing radiation (both lifetime and antenatal), pesticides, and, in utero exposure to cigarette smoke, benzene and nitrogen dioxide (via the mother). Hodgkin lymphoma (HL) is especially associated with higher levels of socioeconomic deprivation, but breast-feeding seems to confer lower risk. This is consistent with an infection or immune-response mediated etiology for HL.
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Affiliation(s)
- Richard J Q McNally
- School of Clinical Medical Sciences, Child Health, University of Newcastle Upon Tyne, UK.
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12
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La prévention du cancer et la relation dose–effet : l’effet cancérogène des rayonnements ionisants. Cancer Radiother 2009; 13:238-58. [DOI: 10.1016/j.canrad.2009.03.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 03/04/2009] [Accepted: 03/20/2009] [Indexed: 01/05/2023]
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13
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Tubiana M, Feinendegen LE, Yang C, Kaminski JM. The linear no-threshold relationship is inconsistent with radiation biologic and experimental data. Radiology 2009; 251:13-22. [PMID: 19332842 PMCID: PMC2663584 DOI: 10.1148/radiol.2511080671] [Citation(s) in RCA: 378] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Maurice Tubiana
- Department of Medicine, Centre Antoine Beclere, Paris, France
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Law GR, Feltbower RG, Taylor JC, Parslow RC, Gilthorpe MS, Boyle P, McKinney PA. What do epidemiologists mean by 'population mixing'? Pediatr Blood Cancer 2008; 51:155-60. [PMID: 18421720 DOI: 10.1002/pbc.21570] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
There is growing evidence that some chronic diseases are caused, or promoted, by infectious disease. 'Population mixing' has been used as a proxy for the range and dose of infectious agents circulating in a community. Given the speculation over the role of population mixing in many chronic diseases, we review the various methods used for measuring population mixing, and provide a classification of these. We recommend that authors fulfill two criteria in publications: measures are demonstrably associated with the putative risk factors for which population-mixing is acting as a proxy and fundamental characteristics of the chosen measures are clearly defined.
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Affiliation(s)
- Graham R Law
- Biostatistics Unit, University of Leeds, Leeds, UK
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15
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Laurier D, Jacob S, Bernier MO, Leuraud K, Metz C, Samson E, Laloi P. Epidemiological studies of leukaemia in children and young adults around nuclear facilities: a critical review. RADIATION PROTECTION DOSIMETRY 2008; 132:182-90. [PMID: 18922823 DOI: 10.1093/rpd/ncn262] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The existence of an increased risk of childhood leukaemia near nuclear installations is a recurrent issue. A review of the related epidemiological literature is presented here. Results for 198 nuclear sites throughout 10 countries were included in the review. In addition to local studies, 25 multi-site studies have been published for eight countries. A large variability was noticed in the quality of the data as well as in the definition of the study population and in the methods of analysis. Many studies present important limits that make the results difficult to interpret. The review confirms that some clusters of childhood leukaemia cases exist locally. However, results based on multi-site studies around nuclear installations do not indicate an increased risk globally. Many studies were launched to investigate possible origins of the observed clusters around specific sites, but up to now, none of the proposed hypotheses have explained them.
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Affiliation(s)
- D Laurier
- Institute for Radiological Protection and Nuclear Safety, IRSN, DRPH/SRBE, BP17, F-92262 Fontenay-aux-Roses Cedex, France.
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Abstract
In a national study, we investigated the incidence of childhood leukaemia (CL) over a 14-year period in France in relation to several measures based on the proportion of individuals who changed address between the last two national censuses. A positive association was found with the proportion of migrants who came from a distant place. The further the migrants came, the higher was the incidence of leukaemia, particularly among children aged 0-4 years in 'isolated' communes at the time of diagnosis (RR=1.4, 95% CI: 1.1,1.8 in the highest category of migration distance). Although the role of the population density was less obvious, a more marked association was found above a certain threshold. No association with the proportion of commuters was observed.
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17
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Belpomme D, Irigaray P, Hardell L, Clapp R, Montagnier L, Epstein S, Sasco AJ. The multitude and diversity of environmental carcinogens. ENVIRONMENTAL RESEARCH 2007; 105:414-29. [PMID: 17692309 DOI: 10.1016/j.envres.2007.07.002] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 06/25/2007] [Accepted: 07/05/2007] [Indexed: 05/16/2023]
Abstract
We have recently proposed that lifestyle-related factors, screening and aging cannot fully account for the present overall growing incidence of cancer. In order to propose the concept that in addition to lifestyle related factors, exogenous environmental factors may play a more important role in carcinogenesis than it is expected, and may therefore account for the growing incidence of cancer, we overview herein environmental factors, rated as certainly or potentially carcinogenic by the International Agency for Research on Cancer (IARC). We thus analyze the carcinogenic effect of microorganisms (including viruses), radiations (including radioactivity, UV and pulsed electromagnetic fields) and xenochemicals. Chemicals related to environmental pollution appear to be of critical importance, since they can induce occupational cancers as well as other cancers. Of major concerns are: outdoor air pollution by carbon particles associated with polycyclic aromatic hydrocarbons; indoor air pollution by environmental tobacco smoke, formaldehyde and volatile organic compounds such as benzene and 1,3 butadiene, which may particularly affect children, and food pollution by food additives and by carcinogenic contaminants such as nitrates, pesticides, dioxins and other organochlorines. In addition, carcinogenic metals and metalloids, pharmaceutical medicines and cosmetics may be involved. Although the risk fraction attributable to environmental factors is still unknown, this long list of carcinogenic and especially mutagenic factors supports our working hypothesis according to which numerous cancers may in fact be caused by the recent modification of our environment.
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Affiliation(s)
- D Belpomme
- Department of Medical Oncology, European Hospital Georges Pompidou (HEGP), University of Paris, F-75015Paris, France.
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Belson M, Kingsley B, Holmes A. Risk factors for acute leukemia in children: a review. ENVIRONMENTAL HEALTH PERSPECTIVES 2007; 115:138-45. [PMID: 17366834 PMCID: PMC1817663 DOI: 10.1289/ehp.9023] [Citation(s) in RCA: 293] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Accepted: 07/13/2006] [Indexed: 05/02/2023]
Abstract
Although overall incidence is rare, leukemia is the most common type of childhood cancer. It accounts for 30% of all cancers diagnosed in children younger than 15 years. Within this population, acute lymphocytic leukemia (ALL) occurs approximately five times more frequently than acute myelogenous leukemia (AML) and accounts for approximately 78% of all childhood leukemia diagnoses. Epidemiologic studies of acute leukemias in children have examined possible risk factors, including genetic, infectious, and environmental, in an attempt to determine etiology. Only one environmental risk factor (ionizing radiation) has been significantly linked to ALL or AML. Most environmental risk factors have been found to be weakly and inconsistently associated with either form of acute childhood leukemia. Our review focuses on the demographics of childhood leukemia and the risk factors that have been associated with the development of childhood ALL or AML. The environmental risk factors discussed include ionizing radiation, non-ionizing radiation, hydrocarbons, pesticides, alcohol use, cigarette smoking, and illicit drug use. Knowledge of these particular risk factors can be used to support measures to reduce potentially harmful exposures and decrease the risk of disease. We also review genetic and infectious risk factors and other variables, including maternal reproductive history and birth characteristics.
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Affiliation(s)
- Martin Belson
- Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Environmental Hazards and Health Effects, Health Studies Branch, Atlanta, Georgia 30341, USA.
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19
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Nyári TA, Kajtár P, Bartyik K, Thurzó L, Parker L. Childhood acute lymphoblastic leukaemia in relation to population mixing around the time of birth in South Hungary. Pediatr Blood Cancer 2006; 47:944-8. [PMID: 16421899 DOI: 10.1002/pbc.20737] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In a retrospective epidemiological study of 481,984 live births in South Hungary, we investigated whether higher levels of population mixing around the time of birth is a risk factor for acute lymphoblastic leukemia (ALL) under age 5 years. Poisson regression was used to investigate the relationship between risk of ALL and the population-mixing index based on the number of incomers in each county district for each year, standardized to have a range of 0-1. Among all children, the risk of ALL increased significantly with increasing population mixing around the time of birth (trend across the range of 0-1 RR = 2.1 95% CI: 1.02-4.44). This effect was more marked for boys (RR = 3.1 95% CI: 1.13-8.51), which supports a sex-specific effect of exposures on risk of ALL.
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Affiliation(s)
- Tibor A Nyári
- Department of Medical Informatics, University of Szeged, Szeged, Hungary
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20
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Rudant J, Baccaïni B, Ripert M, Goubin A, Bellec S, Hémon D, Clavel J. Population-mixing at the place of residence at the time of birth and incidence of childhood leukaemia in France. Eur J Cancer 2006; 42:927-33. [PMID: 16530405 DOI: 10.1016/j.ejca.2005.12.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Revised: 12/06/2005] [Accepted: 12/12/2005] [Indexed: 10/24/2022]
Abstract
The association between the risk of childhood leukaemia before age 7 years and population-mixing at the place of residence at birth was investigated by retrospectively considering all the children born in mainland French communes between 1st January 1990 and 31st December 1998. An increased risk of acute lymphoblastic leukaemia was found with higher levels of migration for children residing at birth in isolated communes with a population density > or =50 people per km2 (SIRR = 2.59, 95% CI: 1.48-4.49). No association was observed with lower population densities. For children residing in non-isolated communes at birth, the results were similar but less marked. The risk tended to increase only for population densities > or =5000 people per km2 (SIRR = 1.57, 95% CI: 0.99-2.52). The findings are consistent with epidemic models and support the hypothesis of an infectious aetiology relating to population-mixing. Population density may be seen as an indicator of the opportunity of contacts between inhabitants and should therefore be taken into account when investigating an infectious hypothesis. This is the first systematic study of population-mixing at the place of residence at the time of birth to be conducted on a national scale.
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Affiliation(s)
- J Rudant
- INSERM, U754, IFR69, Université Paris-Sud XI - 16 Avenue Paul Vaillant Couturier, F-94807 Villejuif Cédex, France
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21
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Abstract
There are three current hypotheses concerning infectious mechanisms in the aetiology of childhood leukaemia: exposure in utero or around the time of birth, delayed exposure beyond the first year of life to common infections and unusual population mixing. No specific virus has been definitively linked with childhood leukaemia and there is no evidence to date of viral genomic inclusions within leukaemic cells. The case-control and cohort studies have revealed equivocal results. Maternal infection during pregnancy has been linked with increased risk whilst breast feeding and day care attendance in the first year of life appear to be protective. There is inconclusive evidence from studies on early childhood infectious exposures, vaccination and social mixing. Some supportive evidence for an infectious aetiology is provided by the findings of space-time clustering and seasonal variation. Spatial clustering suggests that higher incidence is confined to specific areas with increased levels of population mixing, particularly in previously isolated populations. Ecological studies have also shown excess incidence with higher population mixing. The marked childhood peak in resource-rich countries and an increased incidence of the childhood peak in acute lymphoblastic leukaemia (ALL) (occurring at ages 2-6 years predominantly with precursor B-cell ALL) is supportive of the concept that reduced early infection may play a role. Genetically determined individual response to infection may be critical in the proliferation of preleukaemic clones as evidenced by the human leucocyte antigen class II polymorphic variant association with precursor B-cell and T-cell ALL.
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Affiliation(s)
- Richard J Q McNally
- Cancer Research UK Paediatric and Familial Cancer Research Group, Central Manchester and Manchester Children's University Hospitals NHS Trust, Manchester, UK.
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22
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White-Koning ML, Hémon D, Laurier D, Tirmarche M, Jougla E, Goubin A, Clavel J. Incidence of childhood leukaemia in the vicinity of nuclear sites in France, 1990-1998. Br J Cancer 2004; 91:916-22. [PMID: 15280917 PMCID: PMC2409865 DOI: 10.1038/sj.bjc.6602068] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Overall, 670 cases (O) of childhood leukaemia were diagnosed within 20 km of the 29 French nuclear installations between 1990 and 1998 compared to an expected number (E) of 729.09 cases (O/E=0.92, 95% confidence interval (CI)=[0.85–0.99]). Each of the four areas defined around the sites showed non significant deficits of cases (0–5 km: O=65, O/E=0.87, CI=[0.67–1.10]; 5–10 km: O=165, O/E=0.95, CI=[0.81–1.10]; 10–15 km: O=220, O/E=0.88, CI=[0.77–1.00]; 15–20 km: O=220, O/E=0.96, CI=[0.84–1.10]). There was no evidence of a trend in standardised incidence ratio with distance from the sites for all children or for any of the three age groups studied. Similar results were obtained when the start-up year of the electricity-generating nuclear sites and their electric nuclear power were taken into account. No evidence was found of a generally increased risk of childhood leukaemia around the 29 French nuclear sites under study during 1990–1998.
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Affiliation(s)
- M L White-Koning
- Institut National de la Santé et de la Recherche Médicale INSERM - U170-IFR69, 16 avenue Paul Vaillant Couturier, 94807 Villejuif Cedex, France
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23
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Abstract
An infective, mostly viral, basis has been found in an increasing number of different human cancers. In all cases, the neoplasm is a rare response to the relevant infection, which is usually present in persistent form, and requiring specific cofactors for malignancy to develop. In some cases, epidemiological evidence of infectivity preceded and promoted identification of the specific infection involved and even the discovery of the microbe itself, as in Burkitt's lymphoma and cervix cancer. In other cases, the discovery of the agent came first as in stomach and nasopharynx cancers, and epidemiology has been concerned mainly with confirming the relationship, measuring the size of the risk and identifying cofactors. Infection-linked cancers include some of the commonest malignancies in certain large world regions, amounting to over 20% of all cancer in the developing countries. In addition to these cancers are others such as childhood leukaemia that show features indicative of an infective basis though no underlying agent has been identified. Advances in this field invite speculation about possible future discoveries and how these might be promoted. However, in that majority of cancers that are unrelated to sexual behaviour, there will be nothing even at the population level to suggest an infective basis because what is transmitted from one individual to another is not the neoplasm itself, but the underlying, often silent, infection to which the malignancy is an uncommon response. The increasing prevalence of immune impairment in human populations, as a result of the use of immunosuppressive drugs with organ transplants and the spread of HIV infection, has produced marked effects on cancer incidence in the affected groups including increases, of skin cancers, non-Hodgkin's lymphoma and Kaposi's sarcoma and to a lesser extent of many other cancers, in some cases at least due to the release from immunological control of incipient infection-based malignancies.
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Affiliation(s)
- Leo Kinlen
- Cancer Epidemiology Unit, Gibson Building, Radcliffe Infirmary, Oxford OX2 6HE, UK.
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Affiliation(s)
- L Kinlen
- Cancer Epidemiology Unit, Oxford University, Gibson Building, Radcliffe Infirmary, Oxford OX2 6HE, UK
- Cancer Epidemiology Unit, Oxford University, Gibson Building, Radcliffe Infirmary, Oxford OX2 6HE, UK. E-mail:
| | - R Doll
- Clinical Trials Service Unit, Oxford University, Harkness Building, Radcliffe Infirmary, Oxford OX2 6HE, UK
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Wartenberg D, Schneider D, Brown S. Childhood leukaemia incidence and the population mixing hypothesis in US SEER data. Br J Cancer 2004; 90:1771-6. [PMID: 15150603 PMCID: PMC2409734 DOI: 10.1038/sj.bjc.6601734] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We evaluated the infectious aetiology hypothesis of childhood leukaemia that rapid population influx into rural areas is associated with increased risk. Using data from the US SEER program, we found that in changes in rural county population sizes from 1980 to 1989 were associated with incidence rates for childhood acute lymphocytic leukaemia (ALL). The observed associations were strongest among children 0-4 years of age, born in the same state as diagnosis, in extremely rural counties, and when counties adjacent to nonrural counties were excluded. Similar analyses for brain and central nervous system (CNS) cancer in children, a disease less linked to this infectious hypothesis, provide evidence against methodologic bias. Similar evaluations for other decades were not meaningful due to limited sample sizes and, perhaps, increased population mobility.
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Affiliation(s)
- D Wartenberg
- UMDNJ-Robert Wood Johnson Medical School, The Cancer Institute of New Jersey, New Brunswick, NJ, 170 Frelinghuysen Road, Piscataway, NJ 08854, USA.
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