Living on a farm, contact with farm animals and pets, and childhood acute lymphoblastic leukemia: pooled and meta‐analyses from the Childhood Leukemia International Consortium

Orsi, Laurent; Magnani, Corrado; Petridou, Eleni; Dockerty, John D.; Metayer, Catherine; Milne, Elizabeth; Bailey, Helen D.; Dessypris, Nick; Kang, Alice Y.; Wesseling, Catharina; Infante‐Rivard, Claire; Wünsch-Filho, Victor; Mora, Ana M.; Spector, Logan G.; Clavel, Jacqueline

doi:10.1002/cam4.1466

Cited by 19 publications

(16 citation statements)

References 40 publications

(71 reference statements)

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“…Finally, having pets at home has been suggested to be a protective factor for non-communicable diseases in children and adults ( Table 15 ). Specifically, being exposed to pets in the first year of life was found to reduce the risk of acute lymphoblastic leukemia [ 110 ]. For adults, being exposed to a pet was suggested to reduce Crohn’s disease and ulcerative colitis [ 108 ].…”

Section: Resultsmentioning

confidence: 99%

Environmental Risk Factors and Health: An Umbrella Review of Meta-Analyses

Rojas-Rueda

Morales-Zamora

Alsufyani

et al. 2021

IJERPH

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Background: Environmental health is a growing area of knowledge, continually increasing and updating the body of evidence linking the environment to human health. Aim: This study summarizes the epidemiological evidence on environmental risk factors from meta-analyses through an umbrella review. Methods: An umbrella review was conducted on meta-analyses of cohort, case-control, case-crossover, and time-series studies that evaluated the associations between environmental risk factors and health outcomes defined as incidence, prevalence, and mortality. The specific search strategy was designed in PubMed using free text and Medical Subject Headings (MeSH) terms related to risk factors, environment, health outcomes, observational studies, and meta-analysis. The search was limited to English, Spanish, and French published articles and studies on humans. The search was conducted on September 20, 2020. Risk factors were defined as any attribute, characteristic, or exposure of an individual that increases the likelihood of developing a disease or death. The environment was defined as the external elements and conditions that surround, influence, and affect a human organism or population’s life and development. The environment definition included the physical environment such as nature, built environment, or pollution, but not the social environment. We excluded occupational exposures, microorganisms, water, sanitation and hygiene (WASH), behavioral risk factors, and no-natural disasters. Results: This umbrella review found 197 associations among 69 environmental exposures and 83 diseases and death causes reported in 103 publications. The environmental factors found in this review were air pollution, environmental tobacco smoke, heavy metals, chemicals, ambient temperature, noise, radiation, and urban residential surroundings. Among these, we identified 65 environmental exposures defined as risk factors and 4 environmental protective factors. In terms of study design, 57 included cohort and/or case-control studies, and 46 included time-series and/or case-crossover studies. In terms of the study population, 21 included children, and the rest included adult population and both sexes. In this review, the largest body of evidence was found in air pollution (91 associations among 14 air pollution definitions and 34 diseases and mortality diagnoses), followed by environmental tobacco smoke with 24 associations. Chemicals (including pesticides) were the third larger group of environmental exposures found among the meta-analyses included, with 19 associations. Conclusion: Environmental exposures are an important health determinant. This review provides an overview of an evolving research area and should be used as a complementary tool to understand the connections between the environment and human health. The evidence presented by this review should help to design public health interventions and the implementation of health in all policies approach aiming to improve populational health.

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Section: Resultsmentioning

confidence: 99%

Environmental Risk Factors and Health: An Umbrella Review of Meta-Analyses

Rojas-Rueda

Morales-Zamora

Alsufyani

et al. 2021

IJERPH

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“…In particular Switzerland has one of the highest livestock densities in Europe, with around 1.71 livestock units per hectares of utilized agricultural area in 2010 [44]. Previous studies have found a reduced risk of childhood ALL and lymphoma among children with early life exposure to farm animals [45][46][47], while increased risks were found for other cancer subtypes, such as AML, CNST, germ-cell tumours and astrocytoma [18,47]. Given that about 80% of parents with high likelihood of exposure category belonged to job category "market-oriented crop and animal producers" (S1), it is possible that our analysis was confounded by exposure to farm animals.…”

Section: Discussionmentioning

confidence: 99%

Parental occupational exposure to pesticides and risk of childhood cancer in Switzerland: a census-based cohort study

et al. 2020

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Background: Pesticide exposure is a suspected risk factor for childhood cancer. We investigated the risk of developing childhood cancer in relation to parental occupational exposure to pesticides in Switzerland for the period 1990-2015. Methods: From a nationwide census-based cohort study in Switzerland, we included children aged < 16 years at national censuses of 1990 and 2000 and followed them until 2015. We extracted parental occupations reported at the census closest to the birth year of the child and estimated exposure to pesticides using a job exposure matrix. Cox proportional hazards models, adjusted for potential confounders, were fitted for the following outcomes: any cancer, leukaemia, central nervous system tumours (CNST), lymphoma, non-CNS solid tumours. Results: Analyses of maternal (paternal) exposure were based on approximately 15.9 (15.1) million-person years at risk and included 1891 (1808) cases of cancer, of which 532 (503) were leukaemia, 348 (337) lymphomas, 423 (399) CNST, and 588 (569) non-CNS solid tumours. The prevalence of high likelihood of exposure was 2.9% for mothers and 6.7% for fathers. No evidence of an association was found with maternal or paternal exposure for any of the outcomes, except for "non-CNS solid tumours" (High versus None; Father: adjusted HR [95%CI] =1.84 [1.31-2.58]; Mother: 1.79 [1.13-2.84]). No evidence of an association was found for main subtypes of leukaemia and lymphoma. A post-hoc analysis on frequent subtypes of "non-CNS solid tumours" showed positive associations with wide CIs for some cancers. Conclusion: Our study suggests an increased risk for solid tumours other than in the CNS among children whose parents were occupationally exposed to pesticides; however, the small numbers of cases limited a closer investigation of cancer subtypes. Better exposure assessment and pooled studies are needed to further explore a possible link between specific childhood cancers types and parental occupational exposure to pesticides.

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“…Further support for this hypothesis stems from a recent large-scale pooled and meta-analysis of 7847 leukemia cases (immunophenotype: 76% B-lineage, 10% T-ALL, rest unspecified/unknown) and 11 667 controls by the Childhood Leukemia International Consortium. 47 The consortium demonstrated that regular contact with livestock, poultry, and pets in infancy (<1 year of age) reduced the risk of ALL development significantly. 47 The reduced risk associated with contact with livestock was remarkably clear (odds ratio = 0.65; 95% confidence interval, 0.50-0.85).…”

Section: Evidence For Training Of Immune Cells In Bcp-allmentioning

confidence: 99%

Toward prevention of childhood ALL by early-life immune training

Hauer

Fischer

2021

Blood

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B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most common form of childhood cancer. Chemotherapy is associated with life-long health sequelae and fails in approximately 20% of cases. Thus, prevention of leukemia would be preferable to treatment. Childhood leukemia frequently starts before birth, during fetal hematopoiesis. A first genetic hit (e.g. the ETV6-RUNX1 gene fusion) leads to the expansion of pre-leukemic B-cell clones, which are detectable in healthy newborn cord blood (up to 5%). These pre-leukemic clones give rise to clinically overt leukemia in only about 0.2% of carriers. Experimental evidence suggests that a major driver of conversion from the pre-leukemic to the leukemic state is exposure to immune challenges. Novel insights have shed light on immune host responses and how they shape the complex interplay between (A) inherited or acquired genetic predispositions, (B) exposure to infection, and (C) abnormal cytokine release from immunologically untrained cells. Here, we integrate the recently emerging concept of "trained immunity" into existing models of childhood BCP-ALL and suggest future avenues towards leukemia prevention.

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Living on a farm, contact with farm animals and pets, and childhood acute lymphoblastic leukemia: pooled and meta‐analyses from the Childhood Leukemia International Consortium

Cited by 19 publications

References 40 publications

Environmental Risk Factors and Health: An Umbrella Review of Meta-Analyses

Environmental Risk Factors and Health: An Umbrella Review of Meta-Analyses

Parental occupational exposure to pesticides and risk of childhood cancer in Switzerland: a census-based cohort study

Toward prevention of childhood ALL by early-life immune training

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