Allergy and risk of childhood leukaemia: results from the UKCCS

The relationship between childhood leukaemia and childhood asthma: A pharmacoepidemiological study from the Netherlands

BACKGROUND

It has been suggested that childhood asthma lowers the risk of childhood leukaemia. Studies have found an inverse association between these conditions. However, most studies on this relationship are based on questionnaires and telephone interviews, introducing recall bias. Therefore, we conducted a matched case-control study based on drug prescription data to assess the relationship between both conditions.

METHODS

In a large database, covering more than one million individuals, we identified cases of children who had been prescribed 6-mercaptopurine (6-MP). This drug is used in the outpatient maintenance therapy of childhood leukaemia. We matched every child with leukaemia on sex and age (±6 months) to children without leukaemia (controls). The variable of having had asthma was defined as receiving at least two prescriptions for an inhaled corticosteroid within 12 months.

RESULTS

We identified 59 children aged 2-18 who had been prescribed 6-MP (cases), and they were matched to 21,918 controls. Of the children with childhood leukaemia, three (5%) had childhood asthma, whereas in the control group 4889 (22%) had childhood asthma (odds ratio [OR] 0.19; 95% confidence interval 0.06-0.60).

CONCLUSION

In this study on the relationship between childhood asthma and childhood leukaemia, we found a strong inverse association.

Association of TNF-α rs1800629 with Adult Acute B-Cell Lymphoblastic Leukemia

TNF−α influences lymphomagenesis by upregulating proinflammatory and antiapoptotic pathways. In this study, we evaluated the frequency of TNF−α rs1800629 (−308 G>A) polymorphism in newly diagnosed adult patients with acute lymphoblastic leukemia (ALL) and its correlation with age at diagnosis, gender and subtype of ALL. In this case control study, a total of 330 individuals were recruited, including 165 newly diagnosed adult patients with ALL, from the Radiation and Isotope Center in Khartoum (RICK) and 165 healthy normal controls. TNF−α rs1800629 polymorphism was tested through allele-specific polymerase chain reaction (PCR) assay. The frequency of the rs1800629 GA genotype was high (70.9% vs. 60%, OR = 1.84) in the patient group as compared to healthy controls, whereas GG and AA genotypes did not exhibit any statistically significant difference between controls and patients. Based on subtype, GG and GA rs1800629 genotypes showed increased risk of B-ALL (OR 0.46 and 2.12, respectively), whereas rs1800629 GG, GA and AA genotypes did not show any disease association with T-ALL (p > 0.05). Age at diagnosis and gender did not exhibit any association of rs1800629 with ALL in the patient group. In conclusion, rs1800629 is associated with high risk of adult B-ALL, with an insignificant effect of age at diagnosis and gender.

Potential Correlation Between Eczema and Hematological Malignancies Risk: A Systematic Review and Meta-Analysis

Background

Eczema characterized by itch, sleeplessness, and adverse effects on quality of life is associated with a risk of hematological malignancies. However, there is a controversy pertaining to whether this association implies a greater or lesser risk of hematological cancers. We aimed to explore the link between eczema and hematological malignancies risk.

Methods

We systematically searched PubMed and Embase databases from their inception to February 17, 2022. Two reviewers independently screened articles, extracted data and assessed study quality, respectively. The odds ratios and 95% confidence intervals (CIs) were pooled by using fixed or random-effects models.

Results

29 studies involving 2,521,574 participants examined the contribution of eczema to hematological malignancies. We found that eczema significantly increased the risk of Hodgkin's lymphoma (1.44; 95% CI, 1.07–1.95), myeloma (1.15; 95% CI, 1.04–1.28), and significantly decreased the risk of lymphocytic leukemia (0.91; 95% CI, 0.84–0.99); however, it is not significantly associated with Non-Hodgkin's lymphoma, and myelocytic leukemia.

Conclusion

Eczema has been shown to be associated with the risk of hematological cancer, this association still needs to be verified in large randomized controlled trials.

Systematic Review Registration

https://inplasy.com/, INPLASY202260097.

Allergies, genetic polymorphisms of Th2 interleukins, and childhood acute lymphoblastic leukemia: The ESTELLE study

CONTEXT

A negative association between a history of allergy and childhood acute lymphoblastic leukemia (ALL) has been reported in previous studies, but remains debated. This work aimed to investigate this association accounting for genetic polymorphisms of the Th2 pathway cytokines (IL4, IL10, IL13, and IL4R).

METHODS

Analyses were based on the French case-control study ESTELLE (2010-2011). The complete sample included 629 ALL cases and 1421 population-based controls frequency-matched on age and gender. The child's medical history was collected through standardized maternal interview. Biological samples were collected, and genotyping data were available for 411 cases and 704 controls of European origin. Odds ratios (OR) were estimated using unconditional regression models adjusted for potential confounders.

RESULTS

In the complete sample, a significant inverse association was observed between ALL and reported history of allergic rhinitis or sinusitis (OR = 0.65 [0.42-0.98]; P = 0.04), but there was no obvious association with allergies overall. There was an interaction between genetic polymorphisms in IL4 and IL4R (P_{interaction =} 0.003), as well as a gene-environment interaction between IL4R-rs1801275 and a reported history of asthma (IOR = 0.23; P_int  = 0.008) and eczema (IOR = 0.47; P_int  = 0.06). We observed no interaction with the candidate polymorphisms in IL4 and IL13.

CONCLUSION

These results suggest that the association between allergic symptoms and childhood ALL could be modified by IL4R-rs1801275, and that this variant could also interact with a functional variant in IL4 gene. Although they warrant confirmation, these results could help understand the pathological mechanisms under the reported inverse association between allergy and childhood ALL.

Current status and perspectives regarding the association between allergic disorders and cancer

While activation of immune system may lead to a lower risk of some diseases, it has been shown that a history of atopic allergic disorders such as asthma, hay fever, eczema, and food allergies could be related to several types of cancer. However, the evidence is not entirely conclusive. Two proposals suggest a possible mechanism for the association between allergic disorders and cancers: immune surveillance and the antigenic stimulation. The association of allergy and cancer may vary by cancer site and the type of exposure. The aim of current review was to summarize the current knowledge of the association between allergic diseases and the risk of cancers with particular emphasis on case-controls and cohort studies to estimate the cancer risk associated with allergy.

Incidence of cancer after asthma development: 2 independent population-based cohort studies

BACKGROUND

Evidence regarding the risk of cancer development after asthma diagnosis is controversial and inconclusive.

OBJECTIVE

This study sought to determine whether asthma is associated with an increased risk for incident cancer.

METHODS

Two independent, population-based, longitudinal cohorts were examined, and estimated hazard ratios were determined using Cox regression. One group consisted of an unmatched cohort of 475,197 participants and a propensity score-matched cohort of 75,307 participants from the National Health Insurance Service-National Sample Cohort (NHIS-NSC; claims-based data from 2003 to 2015). The other group consisted of 5,440 participants from the Ansan-Ansung cohort (interview-based data from 2001 to 2014).

RESULTS

The NHIS-NSC matched cohort had 572,740 person-years of follow-up, 6,885 people with new asthma diagnoses, and 68,422 people without asthma diagnoses. Adults with asthma had a 75% greater risk of incident cancer overall. The excess risk for incident cancer was greatest during the first 2 years after asthma diagnosis, and this risk remained elevated throughout follow-up. Patients with nonatopic asthma had a greater risk of overall cancer than those with atopic asthma. A high cumulative dose of inhaled corticosteroids among asthma patients was associated with a 56% reduced risk of lung cancer, but had no effect on the risk of overall cancer. The results from the NHIS-NSC unmatched cohort and the Ansan-Ansung cohort were similar to the primary results from the NHIS-NSC matched cohort.

CONCLUSIONS

Asthma development was associated with an increased risk of subsequent cancer in 2 different Korean cohorts. Our findings provide an improved understanding of the pathogenesis of asthma and its relationship with carcinogenesis and suggest that clinicians should be aware of the higher risk of incident cancer among patients with asthma.

Early immune stimulation and childhood acute lymphoblastic leukemia in Costa Rica: A comparison of statistical approaches

BACKGROUND

Although epidemiologic studies suggest that early immune stimulation is protective against childhood leukemia, evidence for this relationship is equivocal for Hispanic children, who are disproportionately affected by this disease. The complex biological processes underlying immune stimulation and leukemogenesis may benefit from novel statistical approaches that account for mixed exposures and their nonlinear interactions. In this study, we utilized targeted machine learning and traditional statistical methods to investigate the association of multiple measures of early immune stimulation with acute lymphoblastic leukemia (ALL) in Costa Rican children.

MATERIALS AND METHODS

We used data from a population-based case-control study conducted in Costa Rica (2001-2003). Cases of ALL (n = 240) were diagnosed in 1995-2000 (age >1 year and <15 years at diagnosis) and were identified through the National Cancer Registry and National Children's Hospital. Population controls (n = 578) were frequency-matched to cases by birth year and drawn from the National Birth Registry. Data on surrogate measures of early immune stimulation were collected through in-home interviews. We fitted multivariable models, utilizing targeted causal inference (varimpact), unconditional logistic regression, and latent class analysis (LCA).

RESULTS

In varimpact analysis, contact with any pet [risk difference (RD) = -0.17, 95% CI: -0.25, -0.10)] or any farm animal (RD = -0.07, 95% CI: -0.13, 0.00) and allergies (RD = -0.08, 95% CI: -0.17, 0.01) were associated with a reduced risk of ALL, whereas experiencing a fever longer than one week was associated with an increased risk (RD = 0.23, 95% CI: 0.12, 0.33). In unconditional logistic regression models, contact with any pet or farm animal and a complete vaccination scheme were inversely associated with odds of ALL (OR = 0.44, 95% CI: 0.31, 0.62; OR = 0.66, 95% CI: 0.49, 0.90; OR = 0.45, 95% CI: 0.24, 0.83; respectively), whereas experiencing a fever longer than one week was positively associated with ALL (OR = 2.44, 95% CI: 1.61, 3.70). Two-class and three-class LCA revealed a group with elevated risk for ALL whose exposure profile was mainly characterized by reduced exposure to pets and farm animals.

CONCLUSIONS

Using distinct statistical approaches, we observed that exposure to pets and farm animals was inversely associated with ALL risk, whereas having a fever longer than one week (a putative proxy of severe infection) was associated with an increased risk. For multifactorial diseases such as childhood leukemia, we recommend estimating the joint effects of multiple exposures by applying diverse statistical methods and interpreting their results together. Overall, we found support for the hypothesis that early immune stimulation offers protection against childhood ALL.

Allergies and Childhood Acute Lymphoblastic Leukemia: A Case-Control Study and Meta-analysis

Background: Allergic disease is suspected to play a role in the development of childhood acute lymphoblastic leukemia (ALL). Studies conducted over the last several decades have yielded mixed results.Methods: We examined the association between allergy, a common immune-mediated disorder, and ALL in the California Childhood Leukemia Study (CCLS), a case-control study of 977 children diagnosed with ALL and 1,037 matched controls (1995-2015). History of allergies in the first year of life was obtained from interviews, mainly reported by mothers. Logistic regression analyses were conducted to estimate ORs and 95% confidence intervals (CIs), controlling for birth order, daycare attendance, and mode of delivery. In addition, we conducted meta-analyses with data from the CCLS and 12 published studies and employed a new method to estimate between-study heterogeneity (R_b).Results: Overall, no associations were observed between childhood ALL risk and specific allergy phenotypes or any allergy, as a group. However, having any allergy was associated with an increased risk of ALL among the youngest study participants. In the meta-analysis random-effects models, reduced odds of ALL were associated with hay fever (metaOR = 0.65; 95% CI, 0.47-0.90); however, restricting the analysis to studies that used medical records for assessment of allergy or recently published studies led to null or attenuated results.Conclusions: Overall, our findings do not support a clear association between allergy and childhood ALL.Impact: The degree to which epidemiologic studies can inform the relationship between allergies and risk of childhood ALL is limited by R_b. Cancer Epidemiol Biomarkers Prev; 27(10); 1142-50. ©2018 AACR.

Genetic polymorphisms of Th2 interleukins, history of asthma or eczema and childhood acute lymphoid leukaemia: Findings from the ESCALE study (SFCE)

BACKGROUND

Previous studies on the putative role of allergy in the aetiology of childhood leukaemia have reported contradictory results. The present study aimed to analyse the relation between a medical history of asthma or eczema and childhood acute lymphoid leukaemia (ALL) in light of potential candidate gene-environment interactions.

METHODS

Analyses were based on a subset of 434 cases of ALL and 442 controls successfully genotyped and of European ancestry children enrolled in a French population-based case-control study conducted in 2003-2004. Information about medical history was obtained during a standardized interview with the mothers. Candidate polymorphisms in genes of the Th2 cytokines IL4, IL10, IL13 and IL4-receptor, were genotyped or imputed.

RESULTS

None of the variant alleles were directly associated with childhood acute lymphoid leukaemia. A medical history of asthma or eczema was reported more often in the control group (OR = 0.7 [0.5-1.0]). This association was mostly seen in the group of children not carrying the IL13-rs20541 variant allele (Interaction Odds Ratio IOR 1.9, p-interaction = 0.07) and in those carrying the IL10 triple variant haplotype (IOR 0.5, p-interaction = 0.04). No interaction was observed with the candidate polymorphisms in IL4 and IL4R.

CONCLUSION

This study provides a new insight into the relationship between allergic symptoms and childhood acute lymphoid leukaemia, by suggesting this inverse association could be limited to children carrying certain genetic polymorphisms. If confirmed, these results could help better understand the biological mechanisms involved in the development of childhood acute lymphoid leukaemia.

Risks for comorbidity in children with atopic disorders: an observational study in Dutch general practices

OBJECTIVE

This study aimed to investigate both atopic and non-atopic comorbid symptoms and diseases in children with physician-diagnosed atopic disorders (atopic eczema, asthma and allergic rhinitis).

METHODS

All children aged 0-18 years listed in a nationwide primary care database (the Netherlands Institute for Health Services Research-Primary Care Database) with routinely collected healthcare data in 2014 were selected. Children with atopic disorders were matched on age and gender with non-atopic controls within the same general practice. A total of 404 International Classification of Primary Care codes were examined. Logistic regression analyses were performed to examine the associations between the presence of atopic disorders and (non-)atopic symptoms and diseases by calculating ORs.

RESULTS

Having one of the atopic disorders significantly increased the risk of having other atopic-related symptoms, even if the child was not registered as having the related atopic disorder. Regarding non-atopic comorbidity, children with atopic eczema (n=15 530) were at significantly increased risk for (infectious) skin diseases (OR: 1.2-3.4). Airway symptoms or (infectious) diseases (OR: 2.1-10.3) were observed significantly more frequently in children with asthma (n=7887). Children with allergic rhinitis (n=6835) had a significantly distinctive risk of ear-nose-throat-related symptoms and diseases (OR: 1.5-3.9). Neither age nor gender explained these increased risks.

CONCLUSION

General practitioners are not always fully aware of relevant atopic and non-atopic comorbidity. In children known to have at least one atopic disorder, specific attention is required to avoid possible insufficient treatment and unnecessary loss of quality of life.

Atopy and Specific Cancer Sites: a Review of Epidemiological Studies

Mounting evidence appears to link asthma and atopy to cancer susceptibility. This review presents and discusses published epidemiological studies on the association between site-specific cancers and atopy. PubMed was searched electronically for publications between 1995 and 2015, and cited references were researched manually. Quantitative studies relating to atopy, allergy, or asthma and cancer were identified and tabulated. Despite many exposure-related limitations, patterns in the studies were observed. Asthma, specifically, has been observed to be a risk factor for lung cancer. A protective effect of atopic diseases against pancreatic cancer has been shown consistently in case-control studies but not in cohort studies. Allergy of any type appears to be protective against glioma and adult acute lymphoblastic leukemia. Most studies on atopic diseases and non-Hodgkin lymphoma or colorectal cancer reported an inverse association. The other sites identified had varying and non-significant outcomes. Further research should be dedicated to carefully defined exposure assessments of "atopy" as well as the biological plausibility in the association between atopic diseases and cancer.

Association of atopic diseases and parvovirus B19 with acute lymphoblastic leukemia in childhood and adolescence in the northeast of Brazil

BACKGROUND

Several factors related to the immune system, such as a history of allergies and virus infections, may be associated with acute lymphoblastic leukemia (ALL). The purpose of this study was to analyze whether the presence of atopic diseases and previous infection with parvovirus B19 and Epstein-Barr virus (EBV) are associated with the development of ALL.

METHODS

This case-control study was performed in two tertiary hospitals located in northeastern Brazil. The study population included 60 patients who were diagnosed with non-T-cell ALL using myelogram and immunophenotyping and 120 patients in the control group. Atopy was evaluated via a parent questionnaire and medical records. Total immunoglobulin (Ig)E and IgG levels of parvovirus B19 and EBV were measured in the serum. Logistic regression was performed to assess the association between variables and odds of ALL.

RESULTS

We identified a significant inverse association between rhinitis, urticaria and elevated IgE serum levels with ALL. A history of parvovirus B19 infection showed a significant association with this type of cancer [OR (95 % CI) 2.00 (1.94-4.26); P = 0.050]. In logistic regression, the presence of atopy was a protective factor [OR (95 % CI) 0.57 (0.38-0.83); P = 0.004], and the presence of IgG for parvovirus B19 was an important risk factor for ALL [OR (95 % CI) 2.20 (1.02-4.76); P = 0.043].

CONCLUSIONS

These results suggest that atopic diseases and elevated total IgE levels are associated with a potential protective effect on the development of ALL. Previous infection with parvovirus B19 contributed to ALL susceptibility.

Limited but durable changes to cellular gene expression in a model of latent adenovirus infection are reflected in childhood leukemic cell lines

Mucosal lymphocytes support latent infections of species C adenoviruses. Because infected lymphocytes resist re-infection with adenovirus, we sought to identify changes in cellular gene expression that could inhibit the infectious process. The expression of over 30,000 genes was evaluated by microarray in persistently infected B-and T-lymphocytic cells. BBS9, BNIP3, BTG3, CXADR, SLFN11 and SPARCL1 were the only genes differentially expressed between mock and infected B cells. Most of these genes are associated with oncogenesis or cancer progression. Histone deacetylase and DNA methyltransferase inhibitors released the repression of some of these genes. Cellular and viral gene expression was compared among leukemic cell lines following adenovirus infection. Childhood leukemic B-cell lines resist adenovirus infection and also show reduced expression of CXADR and SPARCL. Thus adenovirus induces limited changes to infected B-cell lines that are similar to changes observed in childhood leukemic cell lines.

Reported associations between asthma and acute lymphoblastic leukemia: insights from a hybrid simulation study

Numerous studies have reported a protective association between asthma and acute lymphoblastic leukemia (ALL), but the causal structure of this association remains unclear. We present a hybrid simulation to examine the compatibility of this association with uncontrolled confounding by infection or another unmeasured factor. We generated a synthetic cohort using inputs on the interrelations of asthma, ALL, infections, and other suggested risk factors from the literature and the Danish National Birth Cohort. We computed odds ratios (ORs) between asthma and ALL in the synthetic cohort with and without adjustment for infections and other (including unmeasured) confounders. Only if infection was an extremely strong risk factor for asthma (OR of 10) and an extremely strong protective factor against ALL (OR of 0.1) was the asthma-ALL association compatible with the literature (OR of 0.78). Similarly, strong uncontrolled confounding by an unmeasured factor could downwardly bias the asthma-ALL association, but not enough to replicate findings in the literature. This investigation illustrates that the reported protective association between asthma and ALL is unlikely to be entirely due to uncontrolled confounding by infections or an unmeasured confounder alone. Simulation can be used to advance our understanding of risk factors for rare outcomes as demonstrated by this study.

The associations between maternal factors during pregnancy and the risk of childhood acute lymphoblastic leukemia: A meta-analysis

BACKGROUND

Although genetic and environmental factors are considered to be the main causes of acute lymphoblastic leukemia, the associations between maternal factors during pregnancy and the childhood ALL is still unclear.

PROCEDURE

In this study, meta-analysis was used. Medline, PubMed, and Web of Science were searched. The result was assessed based on pooled odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

The pooled ORs showed that there were associations between childhood ALL and the birth order (The first vs others, OR = 1.08, 95%CI = 1.00-1.16), the education of pregnant woman (>high school vs ≤ high school, OR = 0.82, 95%CI = 0.77-0.86), smoking (Ever vs never, OR = 1.10, 95%CI = 1.02-1.19).

CONCLUSIONS

Our meta-analysis showed that there were important associations between childhood ALL and the birth order, the education of pregnant woman, smoking.

Association of asthma with the risk of acute leukemia and non-Hodgkin lymphoma

An increasing incidence of hematological malignancies has been observed in children and adults worldwide over the last few decades. Asthma is a common chronic inflammatory disease. The aim of the present meta-analysis was to evaluate the potential association between a history of asthma and the risk of acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML) and non-Hodgkin lymphoma (NHL). A literature search was performed through PubMed and the Cochrane Database of Systematic Reviews and the Newcastle-Ottawa Scale was used to evaluate the quality of the selected studies. The I² index was used to evaluate heterogeneity and the outcome was measured as the odds ratio (OR) by the random-effects model. A total of 16 case-control studies were included. All the studies were of high quality. The OR for ALL was 0.90 [95% confidence interval (CI): 0.68-1.19; P=0.45; I²=79%]. The OR for AML was 0.85 (95% CI: 0.67-1.08; P=0.19; I²=8%). The OR for NHL was 0.91 (95% CI: 0.83-1.00; P=0.05; I²=0%). Asthma was found to be inversely associated with the risk of NHL. A negative trend of association of asthma with ALL and AML was also observed. However, additional large prospective studies are required to confirm these findings.

Immune-related conditions and acute leukemia in children with Down syndrome: a Children's Oncology Group report

BACKGROUND

Children with Down syndrome have unique immune profiles and increased leukemia susceptibility.

METHODS

Mothers of 158 children with Down syndrome diagnosed with acute leukemia at 0 to 19 years in 1997 to 2002 and 173 children with Down syndrome but no leukemia were interviewed. Associations were evaluated via multivariable unconditional logistic regression.

RESULTS

No associations were detected for asthma, eczema, allergies, or hypothyroidism. Diabetes mellitus associated with leukemia (OR = 9.23; 95% confidence interval 2.33-36.59); however, most instances occurred concurrent with or after the leukemia diagnosis.

CONCLUSIONS AND IMPACT

Children with Down syndrome who develop leukemia have increased diabetes risk, likely due to treatment and underlying susceptibility factors.

Allergy and risk of hematologic malignancies: associations and mechanisms

Increasing evidence indicates that a dysregulated immune system, as the one found in allergic disorders, can affect survival of tumor cells. A possible association between allergies and risk of hematologic malignancies has been examined in several epidemiological studies; however, results were not always consistent. The aim of this review is to report the preclinical and clinical data, which support a correlation between allergy and hematologic neoplasms. Immune system modulation could represent a powerful tool in the prevention and treatment of hematologic malignancies.

Infectious, autoimmune and allergic diseases and risk of Hodgkin lymphoma in children and adolescents: a Children's Oncology Group study

An infectious origin for pediatric Hodgkin lymphoma (HL) has long been suspected and Epstein-Barr virus (EBV) has been implicated in a subset of cases. Increased HL incidence in children with congenital and acquired immunodeficiencies, consistent associations between autoimmune diseases and adult HL and genome-wide association and other genetic studies together suggest immune dysregulation is involved in lymphomagenesis. Here, healthy control children identified by random digit dialing were matched on sex, race/ethnicity and age to HL diagnosed in 1989-2003 at 0-14 years at Children's Oncology Group institutions. Parents of 517 cases and 784 controls completed telephone interviews, including items regarding medical histories. Tumor EBV status was determined for 355 cases. Using conditional logistic regression, we calculated odds ratios (ORs) and 95% confidence intervals (CIs) for risk of HL. Cases were more likely to have had an infection>1 year prior to HL diagnosis (OR=1.69, 95% CI: 0.98-2.91); case siblings were also more likely to have had a prior infection (OR=2.04, 95% CI: 1.01-4.14). Parental history of autoimmunity associated with increased EBV+ HL risk (OR=2.97, 95% CI: 1.34-6.58), while having a parent (OR=1.47, 95% CI: 1.01-2.14) or sibling (OR=1.62, 95% CI: 1.11-2.36) with an allergy was associated with EBV - HL. These results may indicate true increased risk for infections and increased risk with family history of autoimmune and allergic conditions that varies by tumor EBV status, or they may be attributable to inaccurate recall. In addition to employing biomarkers to confirm the role of immune-modulating conditions in pediatric HL, future studies should focus on family based designs.

Allergy and acute leukaemia in children with Down syndrome: a population study. Report from the Mexican inter-institutional group for the identification of the causes of childhood leukaemia

BACKGROUND

Allergies have been described as protective factors against the development of childhood acute leukaemia (AL). Our objective was to investigate the associations between allergy history and the development of AL and acute lymphoblastic leukaemia (ALL) in children with Down syndrome (DS).

METHODS

A case-control study was performed in Mexico City. The cases (n=97) were diagnosed at nine public hospitals, and the controls (n=222) were recruited at institutions for children with DS. Odds ratios (OR) were calculated.

RESULTS

Asthma was positively associated with AL development (OR=4.18; 95% confidence interval (CI): 1.47-11.87), whereas skin allergies were negatively associated (OR=0.42; 95% CI: 0.20-0.91).

CONCLUSION

Our findings suggest that allergies and AL in children with DS share biological and immune mechanisms. To our knowledge, this is the first study reporting associations between allergies and AL in children with DS.

Allergy and risk of childhood acute lymphoblastic leukemia: a population-based and record-based study

A deficit of normal immune stimulation in early childhood is a suspected risk factor for both childhood acute lymphoblastic leukemia (ALL) and allergies. The present study utilized a population-based case-control design using medical claims data from the National Health Insurance Research Database of Taiwan to evaluate the association between allergy and childhood leukemia. Eight hundred forty-six childhood ALL patients who were newly diagnosed during 2000 to 2008 and were older than 1 but less than 10 years of age were individually matched with 3,374 controls based on sex, birth date, and time of diagnosis (reference date for the controls). Conditional logistic regression was performed to assess the association between childhood ALL and allergies. An increased risk of ALL was observed with having an allergy less than 1 year before the case's ALL diagnosis (odds ratio (OR) = 1.7, 95% confidence interval (CI): 1.5, 2.0), more than 1 year before the case's diagnosis (OR = 1.3, 95% CI: 1.1, 1.5), and before the age of 1 year (OR = 1.4, 95% CI: 1.1, 1.7). These results suggest that the pathogenesis of childhood ALL and allergy share a common biologic mechanism.

Invited commentary: childhood acute lymphoblastic leukemia and allergies: biology or bias?

Previous epidemiologic studies have shown an inverse association between a personal history of atopy/allergies, both overall and among asthma, eczema, and hay fever investigated separately, and childhood acute lymphoblastic leukemia (ALL) with some consistency; however, in most of these studies, exposure data were collected by maternal interview. Now, in a population-based and records-based study in this issue of the Journal (Am J Epidemiol. 2012;176(11):970-978), Chang et al. report an increased risk for allergic conditions across different etiologic time periods, calling the former paradigm into doubt. A review of the basic biology literature shows that proposed mechanisms support either a positive or an inverse association. In light of this ambiguity, it is epidemiology's turn to determine the direction of association.

Infectious illness in children subsequently diagnosed with acute lymphoblastic leukemia: modeling the trends from birth to diagnosis

Although there is increasing evidence that immune dysregulation in children who develop acute lymphoblastic leukemia (ALL) is detectable from birth, debate about the role of infectious exposures in infancy continues. With the aim of quantifying children's infectious exposures, investigators have used a number of infection exposure proxies, but there is a lack of consistency in findings, with some markers indicating increased ALL risks and others decreased risks, the disparity being evident both within and between studies. Accordingly, the authors conducted an in-depth analysis of key infection exposure proxies used in the United Kingdom Childhood Cancer Study, a national population-based case-control study conducted over the period 1991-1996, which combined data from medical records, parental interview, and population census. This longitudinal approach revealed the marked deterioration in immune response that emerged around 5 months prior to ALL diagnosis and confirmed that infectious diagnoses in the first year of life were significantly increased (P < 0.05) in children who developed leukemia between 2 and 14 years of age, as well as in those who had birth orders >1, were not breastfed, lived in deprived areas, or were diagnosed with eczema. By contrast, no association between infectious illness and preschool activity was detected, the lower infection levels among controls whose mothers reported attendance contributing to a significantly reduced ALL odds ratio.

Hereditary leukemia due to rare RUNX1c splice variant (L472X) presents with eczematous phenotype

Deleterious mutations in the RUNX1 gene cause hereditary leukemia due to a rare syndrome called Familial platelet Disorder with Associated Myeloid Malignancy (FPDMM). We describe the characteristics of a family with FPDMM due to a novel RUNX1 mutation (L472X), located in the most 3-prime end of the gene reported to date. Our 36-year old proband presented with incidentally detected thrombocytopenia and a family history suggestive of FPDMM. Contrary to previously described families, affected members of our kindred express an eczematous phenotype, reportedly most severe in members who develop leukemia. Pedigree analysis shows that the L472X mutation tracks with thrombocytopenia, acute leukemia, and eczema. The L472X mutation produces a stably expressed RUNX1 protein product with a corresponding decrease in wild type RUNX1 expression. Our data supports the inclusion of eczema in the FPDMM phenotype and suggests the possibility that the RUNX1 L472X mutant causes the type of dominant negative affect that is associated with an elevated risk of leukemia in FPDMM families.

Polymorphisms in the TLR6 gene associated with the inverse association between childhood acute lymphoblastic leukemia and atopic disease

Little is known about the etiology of childhood acute lymphoblastic leukemia (ALL). The presence of atopic disease has been shown to protect against developing childhood ALL. The aim of this study was to examine whether single nucleotide polymorphisms (SNPs) in innate immunity genes previously associated with atopic disease, can elucidate the inverse association between childhood ALL and atopic disease. We studied 525 children, including 192 with childhood ALL, 149 with atopic disease and 184 healthy control subjects. We compared genotype distributions of 29 SNPs in genes of TLR2, TLR4, TLR6, TLR9, TLR10 and CD14 between the three groups and corrected for multiple testing. The genotype distributions of two SNPs in the TLR6 gene, rs5743798 and rs6531666, differed significantly between children with ALL, children with atopic disease and control subjects. Particularly in children with atopic eczema, risk alleles for atopic disease were observed more often than in control subjects, and less often in children with ALL than in control subjects. These findings support the immune surveillance hypothesis as an explanation for the protective association of atopic disease on childhood ALL. Further investigation is warranted to examine in more detail the role of innate immunity in the development of childhood ALL.

Childhood acute leukemia, early common infections, and allergy: The ESCALE Study

This study investigated the role of factors considered related to early stimulation of the immune system in the etiology of childhood acute leukemia. The national registry-based case-control study ESCALE was carried out in France in 2003-2004. Population controls were frequency matched to cases on age and gender. Data were obtained from structured telephone questionnaires administered to mothers. Odds ratios were estimated using unconditional regression models adjusted for potential confounders. Included were 634 acute lymphoblastic leukemia cases, 86 acute myeloblastic leukemia cases, and 1,494 controls aged ≥1 year. Negative associations were observed between acute lymphoblastic leukemia and birth order (P for trend < 0.0001), attendance at a day-care center before age 1 year (odds ratio (OR) = 0.8, 95% confidence interval (CI): 0.6, 1.1), prolonged breastfeeding (OR = 0.7, 95% CI: 0.5, 1.0), repeated early common infections (OR = 0.7, 95% CI: 0.6, 0.9), regular contact with farm animals (OR = 0.6, 95% CI: 0.5, 0.8), frequent farm visits in early life (OR = 0.4, 95% CI: 0.3, 0.6), and history of asthma (OR = 0.7, 95% CI: 0.4, 1.0) or eczema (OR = 0.7, 95% CI: 0.6, 0.9). Results support the hypothesis that repeated early infections and asthma may play a role against childhood acute leukemia.

Genetic polymorphisms in adaptive immunity genes and childhood acute lymphoblastic leukemia

BACKGROUND

Childhood acute lymphoblastic leukemia (ALL) has been hypothesized to have an infection- and immune-related etiology. The lack of immune priming in early childhood may result in abnormal immune responses to infections later in life and increase ALL risk.

METHODS

The current analyses examined the association between childhood ALL and 208 single-nucleotide polymorphisms (SNP) of 29 adaptive immune function genes among 377 ALL cases and 448 healthy controls. Single SNPs were analyzed with a log-additive approach using logistic regression models adjusted for sex, age, Hispanic ethnicity, and race. Sliding window haplotype analyses were done with haplotypes consisting of 2 to 6 SNPs.

RESULTS

Of the 208 SNPs, only rs583911 of IL12A, which encodes a critical modulator of T-cell development, remained significant after accounting for multiple testing (odds ratio for each copy of the variant G allele, 1.52; 95% confidence interval, 1.25-1.85; P = 2.9 x 10(-5)). This increased risk was stronger among firstborn children of all ethnicities and among non-Hispanic children with less day care attendance, consistent with the hypothesis about the role of early immune modulation in the development of childhood ALL. Haplotype analyses identified additional regions of CD28, FCGR2, GATA3, IL2RA, STAT4, and STAT6 associated with childhood ALL.

CONCLUSION

Polymorphisms of genes on the adaptive immunity pathway are associated with childhood ALL risk.

IMPACT

Results of this study support an immune-related etiology of childhood ALL. Further confirmation is required to detect functional variants in the significant genomic regions identified in this study, in particular for IL12A.

Identifying patterns of immune-related disease: use in disease prevention and management

BACKGROUND

Childhood susceptibility to diseases linked with immune dysfunction affects over a quarter of the pediatric population in some countries. While this alone is a significant health issue, the actual impact of immune-related diseases extends over a lifetime and involves additional secondary conditions. Some comorbidities are well known (e.g., allergic rhinitis and asthma). However, no systematic approach has been used to identify life-long patterns of immune-based disease where the primary condition arises in childhood. Such information is useful for both disease prevention and treatment approaches.

DATA SOURCES

Recent primary research papers as well as review articles were obtained from PubMed, Chem Abstracts, Biosis and from the personal files of the authors. Search words used were: the diseases and conditions shown Figs. 1 and 2 in conjunction with comorbid, comorbidities, pediatric, childhood, adult, immune, immune dysfunction, allergy, autoimmune, inflammatory, infectious, health risks, environment, risk factors.

RESULTS

Childhood diseases such as asthma, type-1 diabetes, inflammatory bowel disease, respiratory infections /rhinitis, recurrent otitis media, pediatric celiac, juvenile arthritis and Kawasaki disease are examples of significant childhood health problems where immune dysfunction plays a significant role. Each of these pediatric diseases is associated with increased risk of several secondary conditions, many of which appear only later in life. To illustrate, four prototypes of immune-related disease patterns (i.e., allergy, autoimmunity, inflammation and infectious disease) are shown as tools for: 1) enhanced disease prevention; 2) improved management of immune-based pediatric diseases; and 3) better recognition of underlying pediatric immune dysfunction.

CONCLUSIONS

Identification of immune-related disease patterns beginning in childhood provides the framework for examining the underlying immune dysfunctions that can contribute to additional diseases in later life. Many pediatric diseases associated with dysfunctional immune responses have been linked with an elevated risk of other diseases or conditions as the child ages. Diseases within a pattern may be interlinked based on underlying immune dysfunctions and/or current therapeutic approaches for managing the entryway diseases. It may be beneficial to consider treatment options for the earliest presenting diseases that will concomitantly reduce the risk of immune-linked secondary conditions. Additionally, improved disease prevention is possible with more relevant and age-specific immune safety testing.

The association between atopy and childhood/adolescent leukemia: a meta-analysis

Atopic disease is hypothesized to be protective against several malignancies, including childhood/adolescent leukemia. To summarize the available epidemiologic evidence, the authors performed a meta-analysis of associations between atopy/allergies, asthma, eczema, hay fever, and hives and childhood/adolescent leukemia, acute lymphoblastic leukemia (ALL), and acute myeloid leukemia (AML). They searched MEDLINE literature (1952-March 2009) and queried international experts to identify eligible studies. Ten case-control studies were included. Summary odds ratios and 95% confidence intervals were computed via random-effects models. Odds ratios for atopy/allergies were 1.42 (95% confidence interval (CI): 0.60, 3.35) for 3 studies of leukemia overall, 0.69 (95% CI: 0.54, 0.89) for 6 studies of ALL, and 0.87 (95% CI: 0.62, 1.22) for 2 studies of AML, with high levels of heterogeneity detected for leukemia overall and ALL. Inverse associations were observed for ALL and asthma (odds ratio (OR) = 0.79, 95% CI: 0.61, 1.02), eczema (OR = 0.74, 95% CI: 0.58, 0.96), and hay fever (OR = 0.55, 95% CI: 0.46, 0.66) examined separately. Odds ratios for ALL differed by study design, exposure data source, and latency period, indicating that these factors affect study results. These results should be interpreted cautiously given the modest number of studies, substantial heterogeneity, and potential exposure misclassification but are useful in designing future research.

Aetiology of childhood leukaemia

The acute leukaemias account for about 30% of all malignancy seen in childhood across the Western world. A peak incidence of precursor B cell ALL has emerged as socio-economic conditions have improved in countries worldwide. From twin studies and the use of neonatal blood spots it has been possible to back track the first initiating genetic events within critical haemopoietic cells to foetal development in utero for most precursor B cell ALL and some cases of AML. These events may occur as part of normal foetal development. Whether other factors (environmental or constitutional) are involved to increase the chance of these first genetic changes happening is unclear. For some leukaemias (e.g. infant MLL positive ALL) the first event appears adequate to create a malignant clone but for the majority of ALL and AML further 'genetic' changes are required, probably postnatal. Many environmental factors have been proposed as causative for leukaemia but only ionising irradiation and certain chemicals, e.g. benzene and cytotoxics (alkylators and topoisomerase II inhibitors) have been confirmed and then principally for acute myeloid leukaemia. It appears increasingly likely that delayed, dysregulated responses to 'common' infectious agents play a major part in the conversion of pre-leukaemic clones into overt precursor B cell ALL, the most common form of childhood leukaemia. Constitutional polymorphic alleleic variants in immune response genes (especially the HLA Class II proteins) and cytokines may play a role in determining the type of immune response. High penetrance germ-line mutations are involved in only about 5% of childhood leukaemias (more in AML than ALL). There is little evidence to support any role of viral transformation in causation, unlike in animals. Other environmental factors for which some evidence exists include non-ionising electromagnetic radiation and electric fields, although their mode of action in leukaemogenesis remains unclear. There is no single cause for childhood leukaemia and for most individuals a combination of factors appears to be necessary; all involving gene-environment interactions. To date few clear preventative measures have emerged, except the complete avoidance of first trimester X-rays in pregnancy; a healthy diet with adequate oral folic acid intake both preconception and early in pregnancy; and the early exposure of children to other children outside the home to facilitate stimulation and maturation of the natural immune system. Here then are clear echoes of the "hygiene hypothesis" regarding the initiation of allergies, autoimmune disease and type I diabetes mellitus in children and young people.

Maternal immunoglobulin E and childhood leukemia

Childhood leukemia, particularly acute lymphoblastic leukemia (ALL), has long been hypothesized to be affected by abnormal immune responses to microbial challenges stemming from a lack of immune modulation in early childhood. Studies of allergies suggest that a child's immune development may be modulated by maternal immune status. We conducted a study to explore the relationship between maternal immunoglobulin E (IgE) and childhood leukemia and to investigate whether maternal immune status can influence childhood leukemia risk. Serum total and specific IgE (respiratory and food) were measured in biological mothers of 352 children (193 healthy controls and 159 leukemia cases, including 139 ALL cases) ages <8 years who were enrolled in the Northern California Childhood Leukemia Study. Odds ratios associated with maternal IgE were calculated using unconditional logistic regression adjusted for child's age, sex, race/ethnicity, and annual household income. A positive association between childhood leukemia or ALL and elevated levels of maternal serum total IgE was observed, especially among Hispanics. In addition, a positive association was observed between childhood leukemia or ALL and maternal respiratory or food IgE status. These results suggest that maternal immune function may play a crucial role in the etiology of childhood leukemia, although additional studies need to be conducted to confirm the results of this study and provide a perspective on mechanisms.

Strong association of the HLA-DP6 supertype with childhood leukaemia is due to a single allele, DPB1*0601

We previously reported that susceptibility to childhood B cell precursor ALL (BCP ALL) is associated with HLA-DPB1 alleles having glutamic acid (E) rather than lysine (K) in the P4 antigenic peptide-binding pocket. Clustering approximately 90% of DPB1 alleles into DPB69E (DP2, 6, 8) and DPB69K (DP1, 3, 4) supertypes revealed that DP2 and DP8 are associated with BCP ALL, but DP6 is also associated with non-BCP leukaemia. Here, we report that only one of seven alleles with the DP6 supertype (DPB1(*)0601) is associated with childhood leukaemia (leukaemia vs controls: odds ratio, 95% confidence interval [OR, CI]: 4.6, 2.0-10.4; corrected P=0.019), but not with childhood solid tumours or lymphomas. DPB1(*)0601 is also significantly associated with leukaemia subtypes, including BCP ALL, Pro-B ALL, T-ALL and AML. DPB1(*)0601 is significantly over-transmitted (76.9%) from parents to children with BCP ALL (OR; CI: 4.7; 1.01-22.2). Sequencing the coding region of DPB1(*)0601 revealed an exon 1-4 haplotype [T-DEAV-KIL-RVI] shared with DPB1(*)0301 and 0901, but no evidence of germline mutations in childhood leukaemia. These results suggest that the DPbeta0601 molecule may be functionally involved in childhood leukaemia. Analysis of peptide binding and T-cell activation by DPbeta0601-peptide complexes should help determine its role in childhood leukaemia causation.

Allergies and childhood leukemia

A majority of studies to date have reported an inversed association between allergies and childhood leukemia. However, this association is likely an indirect one and may represent some shared underlying immune mechanisms that have been explained in the context of the "hygiene hypothesis", which has been thought to play an important role in the development of both allergies and childhood leukemia. This review focuses on what we know so far about the role of various immune cells (Th1, Th2, T regulatory and Th17 cells) in the development of allergies and how they may potentially be related to the etiology of childhood leukemia. In addition, the utilities of genetic and molecular studies to disentangle the association between allergies and childhood leukemia and to elucidate the biological mechanisms are also discussed.

Atopic dysfunction and risk of central nervous system tumours in children

Risk factors for central nervous system (CNS) tumours in children remain largely unknown. Evidence of an inverse relationship between atopy and tumour development exists in adults but little is known about childhood tumours. This study aims to examine the risk of childhood CNS tumours given a history of eczema and asthma. Cases of children diagnosed with CNS tumours (n=575) and controls (n=6292) from the UK Childhood Cancer Study (UKCCS) were analysed using conditional logistic regression comparing reported histories of allergic disease. Asthma was statistically significantly and negatively associated with all CNS tumours (odds ratios, OR 0.75, confidence of interval, CI(95%): 0.58-0.97), though this was not observed for eczema (OR 0.94, CI(95%): 0.74-1.18). Individuals who had suffered both asthma and eczema showed the most significant reduction in risk (OR 0.48, CI(95%): 0.28-0.81). Analysis by tumour subtype showed the strongest effect for the medulloblastoma/PNET group. These results may have a biological explanation with raised immunosurveillance in atopic individuals protecting against the development of brain tumours. Alternative explanations might include bias, reverse causality or confounding.