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

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.

Factors Attributed to Breastfeeding Success in a Tertiary Obstetric Hospital

Introduction:

Increasing breastfeeding rates is a national health objective, however substantial barriers and disparities continue to exist in breastfeeding initiation and continuation. Our study aim is to identify factors associated with birthing persons' breastfeeding “success” (patients admitted to Labor & Delivery desiring to breastfeed and discharged breastfeeding) and breastfeeding “failure” (patients admitted to Labor & Delivery desiring to breastfeed and discharged exclusively formula feeding).

Materials and Methods:

We conducted a retrospective cohort study between July 2015 and June 2016. Patients were asked infant feeding plan intentions (breast, formula, combination) upon admission for delivery. Feeding plan was reassessed at discharge from delivery stay and validated to serve as proxy for feeding status at discharge. Logistic regression was used to identify the population(s) most likely to voice intent to breastfeed and to identify predictors of altered breastfeeding intent at discharge.

Results:

Between July 2015 and June 2016, 6690 patients met criteria for analysis. Patients reporting intent to breastfeed before delivery were more likely Caucasian (p < 0.0001), married (p < 0.001), nulliparous (p < 0.01), privately insured (p < 0.0001), educated (p < 0.0001), and older (p < 0.01) compared with patients not intending to breastfeed. These characteristics were similar in those who were “successful breastfeeders,” that is, breastfeeding at discharge. The strongest predictor of breastfeeding at discharge was intent to breastfeed before delivery (p < 0.0001). African American race was the strongest predictor of nonbreastfeeding intent at admission (p < 0.0001) and conversion to formula feeding by hospital discharge (p < 0.001).

Conclusion:

Intent to breastfeed before delivery was the strongest predictor of breastfeeding at discharge; thus, prenatal breastfeeding education within the at-risk population is crucial to increasing breastfeeding rates.

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.

Creation of a nationwide breastfeeding policy for surgical residents: a scoping review protocol

INTRODUCTION

Breast feeding is recommended for the first year of a baby's life due to numerous benefits for both the child and mother. After returning from maternity leave, surgical trainees face extensive barriers to breast feeding and tend to terminate breast feeding earlier than guideline recommendations. The aim of this scoping review is to assess existing breastfeeding policies for surgical trainees at the national level including postgraduate medical education offices, provincial resident unions and individual surgical programmes.

METHODS AND ANALYSIS

A modified Arksey and O'Malley (2005) framework will be used. Specifically, (1) identifying the research question/s and (2) relevant studies from electronic databases and grey literature, (3) identifying and (4) selecting studies with independent verification, and (5) collating, summarising, and reporting data while having ongoing consultation between experts throughout the process. Experts will include a lactation consultant (AGB), a human resource leader (JI), a health information specialist (ES), two independent coders (NZ, LR) and a board-certified surgeon (JD). This work will take place as of December 2020 and be carried out to completion in 2021.

ETHICS AND DISSEMINATION

Ethics approval will not be sought for this scoping review. Research findings will be disseminated through publications, presentations and meetings with relevant stakeholders.

Infant Feeding Practices And Childhood Acute Leukemia: Findings From The Childhood Cancer & Leukemia International Consortium

Increasing evidence suggests that breastfeeding may protect from childhood acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). However, most studies have limited their analyses to any breastfeeding, and only a few data have examined exclusive breastfeeding, or other exposures such as formula milk. We performed pooled analyses and individual participant data meta-analyses of data from sixteen studies (N=17,189 controls; N=10,782 ALL and N=1,690 AML cases) from the Childhood Leukemia International Consortium (CLIC) to characterize the associations of breastfeeding duration with ALL and AML, as well as exclusive breastfeeding duration and age at introduction to formula with ALL. In unconditional multivariable logistic regression analyses of pooled data, we observed decreased odds of ALL among children breastfed 4-6 months (0.88, 95% CI 0.81-0.96) or 7-12 months (OR 0.85, 0.79-0.92). We observed a similar inverse association between breastfeeding ≥4 months and AML (0.82, 95% CI 0.71-0.95). Odds of ALL were reduced among children exclusively breastfed 4-6 months (OR 0.73, 95% CI 0.63-0.85) or 7-12 months (OR 0.70, 95% CI 0.53-0.92). Random effects meta-analyses produced similar estimates, and findings were unchanged in sensitivity analyses adjusted for race/ethnicity or mode of delivery, restricted to children diagnosed ≥1 year of age, or diagnosed with B-ALL. Our pooled analyses indicate that longer breastfeeding is associated with decreased odds of ALL and AML. Few risk factors for ALL and AML have been described, therefore our findings highlight the need to promote breastfeeding for leukemia prevention.

AllergoOncology: Role of immune cells and immune proteins

Background

Immune cells and immune proteins play a pivotal role in host responses to pathogens, allergens and cancer. Understanding the crosstalk between allergic response and cancer, immune surveillance, immunomodulation, role of immunoglobulin E (IgE)‐mediated functions and help to develop novel therapeutic strategies. Allergy and oncology show two opposite scenarios: whereas immune tolerance is desired in allergy, it is detrimental in cancer.

Aim

The current review provides an update on the role of immune cells and immune proteins in allergy and cancer fields.

Methods

Authors investigated the role of relevant immunological markers and the correlation with cancer progression or cancer suppression.

Results

Activated immune cells such as macrophages ‘M1’, dendritic cells (DCs), innate lymphoid cells (ILC2), NK cells, Th1, follicular T helper cells (TFH), TCD8+, B lymphocytes and eosinophils have inhibitory effects on tumourigenesis, while tolerogenic cells such as macrophages ‘M2,’ tolerogenic DCs, ILC3, T and B regulatory lymphocytes appear to favour carcinogenesis. Mastocytes and alarmins can have both effects. RIgE antibodies and CCCL5 chemokine have an anticancer role, whereas IgG4, free light chains, Il‐10, TGF‐β, lipocalin‐2, CCL1 chemokine promote cancer progression. Fundamental is also the contribution of epigenetic changes regulated by the microRNA in cancer progression.

Conclusion

This knowledge represents the key to developing new anticancer therapies.

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.

[Skeletal manifestations of systemic hematologic disorders]

BACKGROUND

Bone marrow consists of connective tissue and stem cells, which generate blood cells. This includes erythropoiesis, leukopoiesis and thrombopoiesis. Thus, hematologic disorders first affect the bone marrow and secondarily the blood.

METHODS

Bone marrow changes can be sensitively detected using magnetic resonance imaging (MRI) and often represent the initial manifestation of the underlying disease. With longer duration of disease, changes can also be found on X‑ray or computed tomography (CT).

RESULTS

The findings on MRI and X‑ray/CT are often nonspecific and can only be interpreted in the context of clinical information.

CONCLUSION

In the following article, we provide a brief overview of the clinical manifestations and imaging changes to be expected in leukemia, anemia, and chronic myeloproliferative disorders.

Identification of Genetic Predispositions Related to Ionizing Radiation in Primary Human Skin Fibroblasts From Survivors of Childhood and Second Primary Cancer as Well as Cancer-Free Controls: Protocol for the Nested Case-Control Study KiKme

BACKGROUND

Therapy for a first primary neoplasm (FPN) in childhood with high doses of ionizing radiation is an established risk factor for second primary neoplasms (SPN). An association between exposure to low doses and childhood cancer is also suggested; however, results are inconsistent. As only subgroups of children with FPNs develop SPNs, an interaction between radiation, genetic, and other risk factors is presumed to influence cancer development.

OBJECTIVE

Therefore, the population-based, nested case-control study KiKme aims to identify differences in genetic predisposition and radiation response between childhood cancer survivors with and without SPNs as well as cancer-free controls.

METHODS

We conducted a population-based, nested case-control study KiKme. Besides questionnaire information, skin biopsies and saliva samples are available. By measuring individual reactions to different exposures to radiation (eg, 0.05 and 2 Gray) in normal somatic cells of the same person, our design enables us to create several exposure scenarios for the same person simultaneously and measure several different molecular markers (eg, DNA, messenger RNA, long noncoding RNA, copy number variation).

RESULTS

Since 2013, 101 of 247 invited SPN patients, 340 of 1729 invited FPN patients, and 150 of 246 invited cancer-free controls were recruited and matched by age and sex. Childhood cancer patients were additionally matched by tumor morphology, year of diagnosis, and age at diagnosis. Participants reported on lifestyle, socioeconomical, and anthropometric factors, as well as on medical radiation history, health, and family history of diseases (n=556). Primary human fibroblasts from skin biopsies of the participants were cultivated (n=499) and cryopreserved (n=3886). DNA was extracted from fibroblasts (n=488) and saliva (n=510).

CONCLUSIONS

This molecular-epidemiological study is the first to combine observational epidemiological research with standardized experimental components in primary human skin fibroblasts to identify genetic predispositions related to ionizing radiation in childhood and SPNs. In the future, fibroblasts of the participants will be used for standardized irradiation experiments, which will inform analysis of the case-control study and vice versa. Differences between participants will be identified using several molecular markers. With its innovative combination of experimental and observational components, this new study will provide valuable data to forward research on radiation-related risk factors in childhood cancer and SPNs.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/32395.

Infections and the development of childhood acute lymphoblastic leukemia: a population-based study

An infectious trigger for childhood acute lymphoblastic leukemia is hypothesized and we assessed the association between the rate, type, and critical exposure period for infections and the development of acute lymphoblastic leukemia. We conducted a matched case-control study using administrative databases to evaluate the association between the rate of infections and childhood acute lymphoblastic leukemia diagnosed between the ages of 2-14 years from Ontario, Canada and we used a validated approach to measure infections. In 1600 cases of acute lymphoblastic leukemia, and 16 000 matched cancer-free controls aged 2-14 years, having >2 infections/year increased the odds of childhood acute lymphoblastic leukemia by 43% (odds ratio = 1.43, 95% confidence interval 1.13-1.81) compared to children with ≤0.25 infections/year. Having >2 respiratory infections/year increased odds of acute lymphoblastic leukemia by 28% (odds ratio =1.28, 95% confidence interval 1.05-1.57) compared to children with ≤0.25 respiratory infections/year. Having an invasive infection increased the odds of acute lymphoblastic leukemia by 72% (odds ratio =1.72, 95% confidence interval 1.31-2.26). Having an infection between the age of 1-1.5 years increased the odds of acute lymphoblastic leukemia by 20% (odds ratio = 1.20, 95% confidence interval 1.04-1.39). Having more infections increased the odds of developing childhood acute lymphoblastic leukemia and having an infection between the ages of 1-1.5 years increased the odds of childhood acute lymphoblastic leukemia.

Breastfeeding Beyond 12 Months: Is There Evidence for Health Impacts?

Because breastfeeding provides optimal nutrition and other benefits for infants (e.g., lower risk of infectious disease) and benefits for mothers (e.g., less postpartum bleeding), health organizations recommend that healthy infants be exclusively breastfed for 4 to 6 months in the United States and 6 months internationally. Recommendations related to how long breastfeeding should continue, however, are inconsistent. The objective of this article is to review the literature related to evidence for benefits of breastfeeding beyond 1 year for mothers and infants. In summary, human milk represents a good source of nutrients and immune components beyond 1 year. Some studies point toward lower infant mortality in undernourished children breastfed for >1 year, and prolonged breastfeeding increases interbirth intervals. Data on other outcomes (e.g., growth, diarrhea, obesity, and maternal weight loss) are inconsistent, often lacking sufficient control for confounding variables. There is a substantial need for rigorous, prospective, mixed-methods, cross-cultural research on this topic. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Untargeted metabolomics of newborn dried blood spots reveals sex-specific associations with pediatric acute myeloid leukemia

The etiology of pediatric acute myeloid leukemia (AML) is largely unknown, but evidence for mutations in utero and long latency periods suggests that environmental factors play a role. Therefore, we used untargeted metabolomics of archived newborn dried blood spots (DBS) to investigate neonatal exposures as potential causal risk factors for AML. Untargeted metabolomics profiling was performed on DBS punches from 48 pediatric patients with AML and 46 healthy controls as part of the California Childhood Leukemia Study (CCLS). Because sex disparities are suggested by differences in AML incidence rates, metabolite features associated with AML were identified in analyses stratified by sex. There was no overlap between the 16 predictors of AML in females and 15 predictors in males, suggesting that neonatal metabolomic profiles of pediatric AML risk are sex-specific. In females, four predictors of AML were putatively annotated as ceramides, a class of metabolites that has been linked with cancer cell proliferation. In females, two metabolite predictors of AML were strongly correlated with breastfeeding duration, indicating a possible biological link between this putative protective risk factor and childhood leukemia. In males, a heterogeneous metabolite profile of AML predictors was observed. Replication with larger participant numbers is required to validate findings.

Birth characteristics and childhood leukemia in Switzerland: a register-based case-control study

Purpose

Initial genetic alterations in the development of childhood leukemia occur in utero or before conception; both genetic and environmental factors are suspected to play a role. We aimed to investigate the associations between childhood leukemia and perinatal characteristics including birth order, birth interval to older siblings, parental age, birth weight, and multiple birth.

Methods

We identified cases diagnosed between 1981 and 2015 and born in Switzerland between 1969 and 2015 from the Swiss Childhood Cancer Registry and randomly sampled five controls per case from national birth records matched on date of birth, sex, and municipality of residence at birth. We used conditional logistic regression to investigate associations between perinatal characteristics and leukemia at ages 0–15 and 0–4 years, and the subtypes acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML).

Results

The study included 1,403 cases of leukemia. We observed increased risks associated with high birth weight (adjusted OR 1.37, 95% CI 1.12–1.69) and multiple birth (1.89, 1.24–2.86). These associations were similar for ALL and stronger for leukemia at ages 0–4 years. For AML, we observed an increased risk for higher birth order (3.08, 0.43–22.03 for fourth or later born children). We found no associations with other perinatal characteristics.

Conclusion

This register-based case–control study adds to the existing evidence of a positive association between high birth weight and risk of childhood leukemia. Furthermore, it suggests children from multiple births are at an increased risk of leukemia.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10552-021-01423-3.

Breastfeeding and the risk of childhood cancer: a systematic review and dose-response meta-analysis

BACKGROUND

The aim of this study was to quantitatively summarize the available evidence on the association of breastfeeding with the risk of childhood cancer.

METHODS

A literature search of PubMed and Embase databases was performed to identify eligible observational studies published from inception to July 17, 2020. The categorical and dose-response meta-analysis was conducted by pooling relative risk (RR) or odds ratio (OR) estimates with 95% confidence intervals (CIs). Potential sources of heterogeneity were detected by meta-regression and stratification analysis. Sensitivity analysis and publication bias test were also carried out.

RESULTS

Forty-five articles involving 475,579 individuals were included in the meta-analysis. Among the thirty-three studies on the association between breastfeeding and risk of childhood leukemia, the pooled risk estimates were 0.77 (95% CI, 0.65-0.91) and 0.77 (95% CI 0.63-0.94) for ever versus non/occasional breastfeeding and longest versus shortest breastfeeding duration group, respectively. There was clear indication for non-linear dose-response relationship between breastfeeding duration and the risk of childhood leukemia (P non-linear < 0.001). The most protective effect (OR, 0.66, 95% CI 0.62-0.70) was observed at a breastfeeding duration of 9.6 months. Four studies examined, the association between breastfeeding and risk of childhood neuroblastoma, and significant inverse associations were consistently observed in both the comparisons of ever breastfeeding versus non/occasional breastfeeding (OR = 0.59, 95% CI 0.44-0.81) and longest versus shortest breastfeeding (OR = 0.61, 95% CI 0.44-0.83). However, no associations of breastfeeding with risk of other cancers were found.

CONCLUSIONS

Our study supports a protective role of breastfeeding on the risk of childhood leukemia, also suggesting a non-linear dose-response relationship. Further studies are warranted to confirm the association between breastfeeding and risk of childhood neuroblastoma.

Vaccination and the Risk of Childhood Cancer-A Systematic Review and Meta-Analysis

INTRODUCTION

Infections may play a role in the etiology of childhood cancer and immunizations may be protective because vaccinations stimulate the immune system. Observational studies reported inconsistent associations between vaccination and risk of childhood cancer. Since a synthesis of the evidence is lacking, we conducted a meta-analysis stratified by histological and site-specific cancer.

METHODS

We performed a systematic review (CRD42020148579) following PRISMA guidelines and searched for literature in MEDLINE, Embase, and the Science Citation Index databases. We identified in three literature databases 7,594 different articles of which 35 met the inclusion criteria allowing for 27 analyses of 11 cancer outcomes after exposure to nine different types of vaccinations. We calculated summary odds ratios (ORs) and 95% confidence intervals (CIs) using random effects models.

RESULTS

We observed four inverse associations between childhood leukemia and certain vaccines as well as the number of vaccinations: OR 0.49 (95% CI = 0.32 to 0.74) for leukemia death after bacillus Calmette-Guérin vaccination; OR 0.76 (95% CI = 0.65 to 0.90) for acute lymphoblastic leukemia after Haemophilus influenzae type b vaccination; OR 0.57 (95% CI = 0.36 to 0.88) for leukemia; and OR 0.62 (95% CI = 0.46 to 0.85) for acute lymphoblastic leukemia after three or more vaccinations of any type. All other conducted analyses did not show any associations.

DISCUSSION

The results are consistent with the hypothesis that vaccinations reduce the risk of childhood leukemia. However, the robustness and validity of these results is limited due to the small number, substantial heterogeneity, and methodological limitations of available studies.

Noncutaneous and Cutaneous Cancer Risk in Patients With Atopic Dermatitis: A Systematic Review and Meta-analysis

Importance

Impaired skin barrier and aberrant immune function in atopic dermatitis (AD) may alter immune response to malignant cancer. Conflicting data exist on the risk of cancer in patients with AD.

Objective

To assess the risk of noncutaneous and cutaneous cancers in patients with AD compared with the general population without AD.

Data Sources

Studies identified from searches of MEDLINE and Embase that were published from 1946 and 1980, respectively, to January 3, 2019. The following search terms were used: [(exp NEOPLASMS/ OR neoplas*.tw. OR tumo*.tw. OR cancer*.tw. OR malignanc*.tw.) AND (exp Dermatitis, Atopic/ OR (atopic adj1 (dermatit* or neurodermatit*)).tw. OR eczema.tw. OR disseminated OR neurodermatit*.tw.)].

Study Selection

Included were observational studies (cohort and case-control designs) reporting a risk estimate for cancer in patients with AD compared with a control group (general population or patients without AD).

Data Extraction and Synthesis

Two independent reviewers extracted data and assessed the risk of bias using the Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) assessment tool, modified for observational exposure studies. Data were pooled using a random-effects model and expressed as standardized incidence ratios (SIRs) or odds ratios (ORs) with 95% CIs. Heterogeneity was assessed using the Cochrane Q statistic and the I2 statistic.

Main Outcomes and Measures

The main outcome of the study was risk of cancer measured by SIRs or ORs.

Results

This systematic review and meta-analysis included 8 population-based cohort studies (n = 5 726 692 participants) and 48 case-control studies (n = 114 136 participants). Among cohort studies, a statistically significant association was found between AD and keratinocyte carcinoma (5 studies; pooled SIR, 1.46; 95% CI, 1.20-1.77) as well as cancers of the kidney (2 studies; pooled SIR, 1.86; 95% CI, 1.14-3.04), central nervous system (2 studies; pooled SIR, 1.81; 95% CI, 1.22-2.70), and pancreas (1 study; SIR, 1.90; 95% CI, 1.03-3.50). Among 48 case-control studies, pooled effects showed patients with AD had statistically significantly lower odds of central nervous system cancers (15 studies; pooled OR, 0.76; 95% CI, 0.70-0.82) and pancreatic cancer (5 studies; pooled OR, 0.81; 95% CI, 0.66-0.98), contrary to the higher incidence found in cohort studies. Case-control studies also demonstrated lower odds of lung and respiratory system cancers (4 studies; pooled OR, 0.61; 95% CI, 0.45-0.82). No evidence of association was found between AD and other cancer types, including melanoma. There was substantial heterogeneity between studies for many other cancers, which precluded pooling of data, and there was moderate to serious risk of bias among included studies.

Conclusions and Relevance

Observational evidence suggests potential associations between AD and increased risk of keratinocyte carcinoma and kidney cancer as well as lower odds of lung and respiratory system cancers. Further research is needed to address the heterogeneity and limitations of current evidence and to better understand the mechanisms underlying a possible association between AD and cancer risk.

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.

Lactational Transfer of Long-Chain Perfluorinated Carboxylic Acids in Mice: A Method to Directly Collect Milk and Evaluate Chemical Transferability

Perfluoroalkyl carboxylic acids (PFCAs), such as perfluorooctanoic acid (PFOA, C8), are a group of industrial chemicals that are detected in the serum of people throughout the world. Long-chain PFCAs (C9 to C13) have high lipophilicity, therefore they may have a high transfer rate to breast milk. This study investigated the lactational transfer of PFCAs with carbon chain lengths of 8 to 13 in mice. Lactating dams were given a single intravenous administration of PFCAs (C8 to C13) during the postnatal period (8–13 days after delivery). Milk was collected from the dam 24 h after administration using a milking device built in-house. Plasma was obtained from the dam at the same time as milk collection. The observed milk/plasma (M/P) concentration ratios were 0.32 for C8, 0.30 for C9, 0.17 for C10, 0.21 for C11, 0.32 for C12, and 0.49 for C13. These results indicate that the M/P concentration ratio is not related to the lipophilicity of PFCAs. However, estimated relative daily intake, an indicator of how much PFCA is transferred from dams to pups per body weight, increased with chain length: 4.16 for C8, 8.98 for C9, 9.35 for C10, 9.51 for C11, 10.20 for C12, and 10.49 for C13, which may be related to the lower clearance of long-chain PFCAs. These results indicate the importance of future risk assessment of long-chain PFCAs.

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.

Occupational livestock or animal dust exposure and offspring cancer risk in Denmark, 1968-2016

OBJECTIVE

To examine associations with occupational livestock or other animal dust exposure and offspring cancer risk.

METHODS

In this population-based case-control study of Danish children aged < 17 years old, 5078 childhood cancer cases diagnosed 1968-2016 were matched to cancer-free controls by birth year and sex (n = 123,228). Occupational livestock or animal dust exposure was identified using a job-exposure matrix. We employed multivariable conditional logistic regression models to estimate associations with offspring cancer for births 1968-2016 and 1989-2016, with the latter timeframe reflecting a period of presumed higher exposure due to changes in Danish farming practices. Sensitivity analyses considered place of birth (urban areas vs. rural areas and small towns).

RESULTS

For births 1968-2016, paternal exposure from offspring birth to cancer diagnosis was associated with central nervous system tumors (adjusted odds ratio [OR] = 1.30, 95% confidence interval [CI] 1.04-1.63) and germ cell tumors (OR = 1.82, 95% CI 1.05-3.27), while maternal pregnancy exposure was associated with astrocytoma (OR = 1.89, 95% CI 1.00-3.57). For births 1989-2016, paternal exposure from offspring birth to cancer diagnosis was negatively associated with acute lymphoid leukemia (OR = 0.58, 95% CI 0.33-1.00). For births in rural areas only, maternal exposure from offspring birth to cancer diagnosis was positively associated with acute myeloid leukemia (OR = 2.16, 95% CI 1.09-4.29).

CONCLUSIONS

This study suggests that paternal occupational animal exposure is associated with offspring germ cell tumors, and maternal pregnancy exposure with astrocytomas. Our results are mixed with respect to leukemia subtypes.

DNA methylation and the hygiene hypothesis: connecting respiratory allergy and childhood acute lymphoblastic leukemia

Aim: The hygiene hypothesis states that a lack of infection in early-life suppresses immune system development, and is linked to respiratory allergy (RA) and childhood acute lymphoblastic leukemia (ALL) risk. Little is known about underlying mechanisms, but DNA methylation is altered in RA and ALL, and in response to infection. We investigated if aberrant methylation may be in common between these diseases and associated with infection. Materials & methods: RA and ALL disease-associated methylation signatures were compared and related to exposure-to-infection signatures. Results: A significant number of genes overlapped between RA and ALL signatures (p = 0.0019). Significant overlaps were observed between exposure-to-infection signatures and disease-associated signatures. Conclusion: DNA methylation may be a mediating mechanism through which the hygiene hypothesis is associated with RA and ALL risk.

A review on the pathophysiology of asthma remission

Asthma is a chronic respiratory condition, which is highly prevalent worldwide. Although no cure is currently available, it is well recognized that some asthma patients can spontaneously enter remission of the disease later in life. Asthma remission is characterized by absence of symptoms and lack of asthma-medication use. Subjects in asthma remission can be divided into two groups: those in clinical remission and those in complete remission. In clinical asthma remission, subjects still have a degree of lung functional impairment or bronchial hyperresponsiveness, while in complete asthma remission, these features are no longer present. Over longer periods, the latter group is less likely to relapse. This remission group is of great scientific interest due to the higher potential to find biomarkers or biological pathways that elicit or are associated with asthma remission. Despite the fact that the definition of asthma remission varies between studies, some factors are reproducibly observed to be associated with remitted asthma. Among these are lower levels of inflammatory markers, which are lowest in complete remission. Additionally, in both groups some degree of airway remodeling is present. Still, the pathological disease state of asthma remission has been poorly investigated. Future research should focus on at least two aspects: further characterisation of the small airways and airway walls in order to determine histologically true remission, and more thorough biological pathway analyses to explore triggers that elicit this phenomenon. Ultimately, this will result in pharmacological targets that provide the potential to steer the course of asthma towards remission.

Ionising radiation and childhood leukaemia revisited

Increased incidences of childhood acute leukaemia were noted among survivors of the atomic bombings of Hiroshima and Nagasaki. In Western societies, Childhood Acute Lymphoblastic Leukaemia has a distinct epidemiology peaking at 3 years old. Exposure to ionising radiation is an established hazard but it is difficult to gauge the precise risk of less than 100 mSv. Since 1983 significant leukaemia incidences have been reported among families residing near nuclear installations. The target cells (naïve neonatal lymphocytes) get exposed to multiple xenobiotic challenges and undergo extraordinary proliferation and physiological somatic genetic change. Population movements and ionising radiation are considered taking account of updated understanding of radiation biology, cancer cytogenetics and immunological diversity. Double Strand Breaks in DNA arise through metabolic generation of Reactive Oxygen Species, and nearly always are repaired; but mis-repairs can be oncogenic. Recombinant Activating Gene enzymes in rapidly dividing perinatal pre-B lymphocytes being primed for antibody diversity are targeted to Signal Sequences in the Immunoglobulin genes. off target pseudo-sequences may allow RAG enzymes to create autosomal DSBs which, when mis-repaired, become translocated oncogenes. Immunogens acting by chance at crucial stages may facilitate this. In such circumstances, oncogenic DSBs from ionising radiation are less likely to be significant.

Infant milk-feeding practices and childhood leukemia: a systematic review

BACKGROUND

During the Pregnancy and Birth to 24 Months Project, the US Departments of Agriculture and Health and Human Services initiated a review of evidence on diet and health in these populations.

OBJECTIVES

The aim of these systematic reviews was to examine the relation of 1) never versus ever feeding human milk, 2) shorter versus longer durations of any human milk feeding, 3) shorter versus longer durations of exclusive human milk feeding, and 4) feeding a lower versus higher intensity of human milk to mixed-fed infants with acute childhood leukemia, generally, and acute lymphoblastic leukemia, specifically.

METHODS

The Nutrition Evidence Systematic Review team conducted systematic reviews with external experts. We searched CINAHL, Cochrane, Embase, and PubMed for articles published January 1980 to March 2016, dual-screened the results using predetermined criteria, extracted data from and assessed risk of bias for each included study, qualitatively synthesized the evidence, developed conclusion statements, and graded the strength of the evidence.

RESULTS

We included 24 articles from case-control or retrospective studies. Limited evidence suggests that never feeding human milk versus 1) ever feeding human milk and 2) feeding human milk for durations ≥6 mo are associated with a slightly higher risk of acute childhood leukemia, whereas evidence comparing never feeding human milk with feeding human milk for durations <6 mo is mixed. Limited evidence suggests that, among infants fed human milk, a shorter versus longer duration of human milk feeding is associated with a slightly higher risk of acute childhood leukemia. None of the included articles examined exclusive human milk feeding or the intensity of human milk fed to mixed-fed infants.

CONCLUSIONS

Feeding human milk for short durations or not at all may be associated with slightly higher acute childhood leukemia risk. The evidence could be strengthened with access to broadly generalizable prospective samples; therefore, we recommend linking surveillance systems that collect infant feeding and childhood cancer data.

The association between birth order and childhood leukemia may be modified by paternal age and birth weight. Pooled results from the International Childhood Cancer Cohort Consortium (I4C)

The "delayed infection hypothesis" states that a paucity of infections in early childhood may lead to higher risks of childhood leukemia (CL), especially acute lymphoblastic leukemia (ALL). Using prospectively collected data from six population-based birth cohorts we studied the association between birth order (a proxy for pathogen exposure) and CL. We explored whether other birth or parental characteristics modify this association. With 2.2 × 106 person-years of follow-up, 185 CL and 136 ALL cases were ascertained. In Cox proportional hazards models, increasing birth order (continuous) was inversely associated with CL and ALL; hazard ratios (HR) = 0.88, 95% confidence interval (CI): (0.77-0.99) and 0.85: (0.73-0.99), respectively. Being later-born was associated with similarly reduced hazards of CL and ALL compared to being first-born; HRs = 0.78: 95% CI: 0.58-1.05 and 0.73: 0.52-1.03, respectively. Successive birth orders were associated with decreased CL and ALL risks (P for trend 0.047 and 0.055, respectively). Multivariable adjustment somewhat attenuated the associations. We found statistically significant and borderline interactions between birth weight (p = 0.024) and paternal age (p = 0.067), respectively, in associations between being later-born and CL, with the lowest risk observed for children born at <3 kg with fathers aged 35+ (HR = 0.18, 95% CI: 0.06-0.50). Our study strengthens the theory that increasing birth order confers protection against CL and ALL risks, but suggests that this association may be modified among subsets of children with different characteristics, notably advanced paternal age and lower birth weight. It is unclear whether these findings can be explained solely by infectious exposures.

Factors Associated with Breastfeeding Initiation and Continuation: A Meta-Analysis

OBJECTIVE

To use a quantitative approach to evaluate the literature for quantity, quality, and consistency of studies of maternal and infant characteristics in association with breastfeeding initiation and continuation, and to conduct a meta-analysis to produce summary relative risks (RRs) for selected factors.

STUDY DESIGN

A systematic review using PubMed and CINAHL through March 2016 was conducted to identify relevant observational studies in developed nations, reporting a measure of risk for 1 or more of 6 quantitatively derived, high impact factors in relation to either breastfeeding initiation or continuation. One author abstracted data using a predesigned database, which was reviewed by a second independent author; data evaluation and interpretation included all co-authors. These factors were summarized using standard meta-analysis techniques.

RESULTS

Six high impact factors were identified (smoking [39 papers], mode of delivery [47 papers], parity [31 papers], dyad separation [17 papers], maternal education [62 papers], and maternal breastfeeding education [32 papers]). Summary RR from random-effects models for breastfeeding initiation were highest for high vs low maternal education (RR 2.28 [95% CI 1.92-2.70]), dyad connection vs not (RR 2.01 [95% CI 1.38-2.92]), and maternal nonsmoking vs smoking (RR = 1.76 [95% CI 1.59-1.95]); results were similar for breastfeeding continuation.

CONCLUSIONS

Despite methodological heterogeneity across studies, relatively consistent results were observed for these perinatally identifiable factors associated with breastfeeding initiation and continuation, which may be informative in developing targeted interventions to provide education and support for successful breastfeeding in more families.

The emerging story of acute lymphoblastic leukemia among the Latin American population - biological and clinical implications

Higher incidence rates and poor outcomes have been reported among Latin American patients (Latinos) with acute lymphoblastic leukemia (ALL). Distinct patterns in recent genomic studies allude to a predisposing genetic component. In this review, we critically examine the increasing amount of empirical information on the epidemiology, outcomes and genomics of Latinos with ALL. We discuss the immense diversity within the Latino community and varying definitions of what is considered Latino, which pose an epidemiological challenge. Environmental factors have been evaluated as possible predisposing factors in the development of ALL but studies have produced conflicting results. In this review we describe chromosomal abnormalities and the specific genomic landscape in Latinos with ALL and their association with unfavorable prognosis, focusing on the higher frequency of Philadelphia chromosome-Like ALL. Recent data suggest an association between polymorphisms that are commonly found in indigenous Americans and high rates of ALL. The review compares the distribution of ALL throughout the various countries in Latin America in an attempt to shed some epidemiological light on the genetic ancestry of ALL. We additionally identify areas where research is warranted in efforts toward the advent of novel targeted agents that are relevant in improving outcomes within the Latino community.

A causal mechanism for childhood acute lymphoblastic leukaemia

In this Review, I present evidence supporting a multifactorial causation of childhood acute lymphoblastic leukaemia (ALL), a major subtype of paediatric cancer. ALL evolves in two discrete steps. First, in utero initiation by fusion gene formation or hyperdiploidy generates a covert, pre-leukaemic clone. Second, in a small fraction of these cases, the postnatal acquisition of secondary genetic changes (primarily V(D)J recombination-activating protein (RAG) and activation-induced cytidine deaminase (AID)-driven copy number alterations in the case of ETS translocation variant 6 (ETV6)-runt-related transcription factor 1 (RUNX1)+ ALL) drives conversion to overt leukaemia. Epidemiological and modelling studies endorse a dual role for common infections. Microbial exposures earlier in life are protective but, in their absence, later infections trigger the critical secondary mutations. Risk is further modified by inherited genetics, chance and, probably, diet. Childhood ALL can be viewed as a paradoxical consequence of progress in modern societies, where behavioural changes have restrained early microbial exposure. This engenders an evolutionary mismatch between historical adaptations of the immune system and contemporary lifestyles. Childhood ALL may be a preventable cancer.

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.

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

The associations between childhood acute lymphoblastic leukemia (ALL) and several factors related to early stimulation of the immune system, that is, farm residence and regular contacts with farm animals (livestock, poultry) or pets in early childhood, were investigated using data from 13 case-control studies participating in the Childhood Leukemia International Consortium. The sample included 7847 ALL cases and 11,667 controls aged 1-14 years. In all studies, the data were obtained from case and control parents using standardized questionnaires. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by unconditional logistic regression adjusted for age, sex, study, maternal education, and maternal age. Contact with livestock in the first year of life was inversely associated with ALL (OR = 0.65, 95% CI: 0.50, 0.85). Inverse associations were also observed for contact with dogs (OR = 0.92, 95% CI: 0.86, 0.99) and cats (OR = 0.87, 95% CI: 0.80, 0.94) in the first year of life. There was no evidence of a significant association with farm residence in the first year of life. The findings of these large pooled and meta-analyses add additional evidence to the hypothesis that regular contact with animals in early childhood is inversely associated with childhood ALL occurrence which is consistent with Greaves' delayed infection hypothesis.

Livestock and poultry density and childhood cancer incidence in nine states in the USA

BACKGROUND

Parental occupational and childhood exposures to farm animals have been positively associated with childhood brain tumors, whereas associations with childhood leukemia are equivocal. The developing immune system may be influenced by allergen, virus, or other exposures from animal sources, which may contribute to childhood cancer incidence.

METHODS

Incident cancers (acute lymphoblastic leukemia [ALL], acute myeloid leukemia [AML], central nervous system [CNS], peripheral nervous system [PNS]) for children aged 0-4 diagnosed between 2003 and 2008 were obtained from nine National Cancer Institute Surveillance, Epidemiology and End Results (SEER) registries and were linked to U.S. Census of Agriculture data from 2002 and 2007 by county of diagnosis. Animal densities (animal units [AU]/km²; one animal unit is 1000 pounds of animal weight) were estimated for hogs, cattle, chickens (layers and broilers, separately), equine (horses, ponies, mules, burros, donkeys), goats, sheep, turkeys, and total animals. Animal density was examined in models as both continuous (AU per km²) and categorical variables (quartiles). Animal operation densities (per km²) by size of operation (cattle, hogs, chickens, sheep) were modeled continuously. Rate ratios and 95% confidence intervals were estimated using Poisson regression.

RESULTS

We found positive associations between AML and broiler chicken densities (RR_{per 10AU/km}² = 1.14, 95% CI = 1.02-1.26). ALL rates increased with densities of hog operations (RRper operation/100km² = 1.06, 95% CI = 1.02-1.11). PNS cancer rates were inversely associated with layer chicken density (RR_{per log of AU/km}² = 0.94, 95% CI = 0.89-0.99). No association was found between any cancer type and densities of cattle, equine, or goats.

CONCLUSIONS

Although limited by the ecologic study design, some of our findings are novel and should be examined in epidemiological studies with individual level data.

A systematic review and meta-analysis of the association between childhood infections and the risk of childhood acute lymphoblastic leukaemia

Background:

To determine whether childhood infections were associated with the development of childhood acute lymphoblastic leukaemia (ALL).

Methods:

We included studies that assessed any infection in childhood prior to the diagnosis of ALL in children aged 0–19 years compared to children without cancer. The primary analysis synthesised any infection against the odds of ALL, and secondary analyses assessed the frequency, severity, timing of infections, and specific infectious agents against the odds of ALL. Subgroup analyses by data source were investigated.

Results:

In our primary analysis of 12 496 children with ALL and 2 356 288 children without ALL from 38 studies, we found that any infection was not associated with ALL (odds ratio (OR)=1.10, 95% CI: 0.95–1.28). Among studies with laboratory-confirmed infections, the presence of infections increased the odds of ALL by 2.4-fold (OR=2.42, 95% CI: 1.54–3.82). Frequency, severity, and timing of infection were not associated with ALL.

Conclusions:

The hypothesis put forward by Greaves and others about an infectious aetiology are neither confirmed nor refuted and the overall evidence remains inadequate for good judgement. The qualitative difference in the subgroup effects require further study, and future research will need to address the challenges in measuring infectious exposures.

Genetic association with B-cell acute lymphoblastic leukemia in allogeneic transplant patients differs by age and sex

The incidence and mortality rates of B-cell acute lymphoblastic leukemia (B-ALL) differ by age and sex. To determine if inherited genetic susceptibility contributes to these differences we performed 2 genome-wide association studies (GWAS) by age, sex, and subtype and subsequent meta-analyses. The GWAS included 446 B-ALL cases, and 3027 healthy unrelated blood and marrow transplant (BMT) donors as controls from the Determining the Influence of Susceptibility Conveying Variants Related to One-Year Mortality after BMT (DISCOVeRY-BMT) study. We identified 1 novel variant, rs189434316, significantly associated with odds of normal cytogenetic B-ALL (odds ratio from meta-analysis [OR_meta] = 3.7; 95% confidence interval [CI], 2.5, 6.2; P value from meta-analysis [P_meta] = 6.0 × 10^-9). The previously reported pediatric B-ALL GWAS variant, rs11980379 (IKZF1), replicated in B-ALL pediatric patients (OR_meta = 2.3; 95% CI, 1.5, 3.7; P_meta = 1.0 × 10^-9), with evidence of heterogeneity (P = .02) between males and females. Sex differences in single-nucleotide polymorphism effect were seen in those >15 years (OR = 1.7; 95% CI, 1.4, 2.2, P_Males = 6.38 × 10^-6/OR = 1.1; 95% CI, 0.8, 1.5; P_Females = .6) but not ≤15 years (OR = 2.3; 95% CI, 1.4, 3.8; P_Males = .0007/OR = 1.9; 95% CI, 1.2, 3.2; P_Females = .007). The latter association replicated in independent pediatric B-ALL cohorts. A previously identified adolescent and young-adult onset ALL-associated variant in GATA3 is associated with B-ALL risk in those >40 years. Our findings provide more evidence of the influence of genetics on B-ALL age of onset and we have shown the first evidence that IKZF1 associations with B-ALL may be sex and age specific.

Childhood cancer incidence by ethnic group in England, 2001-2007: a descriptive epidemiological study

BACKGROUND

After the first year of life, cancers are the commonest cause of death in children. Incidence rates vary between ethnic groups, and recent advances in data linkage allow for a more accurate estimation of these variations. Identifying such differences may help identify potential risk or protective factors for certain childhood cancers. This study thus aims to ascertain whether such differences do indeed exist using nationwide data across seven years, as have previously been described in adult cancers.

METHODS

We obtained data for all cancer registrations for children (aged 0-14) in England from January 2001 to December 2007. Ethnicity (self-assigned) was established through record linkage to the Hospital Episodes Statistics database or cancer registry data. Cancers were classified morphologically according to the International Classification of Childhood Cancer into four groups - leukaemias; lymphomas; central nervous system; and other solid tumours. Age standardised incidence rates were estimated for each ethnic group, as well as incidence rate ratios comparing each individual ethnic group (Indian, Pakistani, Bangladeshi, Black African, Black Carribean, Chinese) to Whites, adjusting for sex, age and deprivation.

RESULTS

The majority of children in the study are UK born. Black children (RR = 1.18, 99% CI: 1.01-1.39), and amongst South Asians, Pakistani children (RR = 1.19, 99% CI: 1.02-1.39) appear to have an increased risk of all cancers. There is an increased risk of leukaemia in South Asians (RR = 1.31, 99% CI: 1.08-1.58), and of lymphoma in Black (RR = 1.72, 99% CI: 1.13-2.63) and South Asian children (RR = 1.51, 99% CI: 1.10-2.06). South Asians appear to have a decreased risk of CNS cancers (RR = 0.71, 99% CI: 0.54-0.95).

CONCLUSIONS

In the tradition of past migrant studies, such descriptive studies within ethnic minority groups permit a better understanding of disease incidence within the population, but also allow for the generation of hypotheses to begin to understand why such differences might exist. Though a major cause of mortality in this age group, childhood cancer remains a relatively rare disease; however, the methods used here have permitted the first nationwide estimation of childhood cancer by individual ethnic group.

Strategically Positioned: Breastfeeding, Advocacy, and the Hands-On Nurse

Breastfeeding, a health behavior that provides well-known benefits for mothers, infants, and children, is an essential strategy to improve public health. Breastfeeding can reduce the incidence of infant illness and death and provides both short- and longterm physiological benefits to mothers. National and international government agencies and grassroots organizations supporting breastfeeding include the World Health Organization, the United Nations International Children's Emergency Fund, the World Alliance for Breastfeeding Action, the Centers for Disease Control and Prevention, and the La Leche League. In the United States, breastfeeding of infants was the norm until the late 1890s when the Progressive Era's emphasis on science and modernity led to the transition of childbirth from residential in-home births to community-based hospital births and the aggressive rise of the baby formula industry. By 1966, only 18% of mothers were exclusively breastfeeding their infants at hospital discharge. This drastic decrease in breastfeeding reduced the percentage of mothers and grandmothers who could share their breastfeeding knowledge and experience. Nurses who provide care for women and infants are essential stakeholders in bridging the breastfeeding knowledge gap by offering education on the short- and long-term health benefits of breastfeeding to both mother and baby and timely encouragement to mothers during the most significant time for establishing lactation.

Systemic immune mechanisms in atopic dermatitis and psoriasis with implications for treatment

Atopic dermatitis (AD) and psoriasis are inflammatory skin diseases that negatively affect patients' quality of life. Although distinctions exist between these diseases, both are characterized by erythematous, thickened epidermal lesions that vary in intensity and affected body surface area. Early models of aetiology attributed symptoms of both diseases to cutaneous inflammation at lesion sites, but recent studies have established that activated immune mediators in the circulation drive disease severity. Activation of T helper 2 (Th2) and Th22 cells in the circulation appears to be the principal initiator of acute AD pathology, with the emergence of Th1 and Th17/interleukin (IL)-23 pathway activation marking the transition to a chronic state. The Th17/IL-23 pathway also has an important role in psoriasis. The role of systemic inflammation in AD and psoriasis is supported by the occurrence of non-cutaneous comorbidities that affect patients, most of which intensify morbidity and disability associated with lesional skin. Atopic dermatitis is associated with allergic disorders consisting of the "atopic march," whereas psoriasis is frequently accompanied by psoriatic arthritis. Patients with both disorders are at significantly higher risk of obesity, metabolic disorders, and cardiovascular diseases, all of which feature inflammatory components in their pathology models. These insights have led to novel therapeutics aimed at addressing psoriasis by targeting tumor necrosis factor- and Th17-related cytokine pathways. The success of these agents in psoriasis management is driving new therapeutic approaches for moderate-to-severe AD, including agents targeting the Th2 and Th17/Th22 cytokine pathways.

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.

Risk of Childhood Cancer and Socio-economic Disparities: Results of the French Nationwide Study Geocap 2002-2010

BACKGROUND

Socio-economic status is related to many life style and environmental factors, some of which have been suggested to influence the risk of childhood cancer. Studies requiring subject participation are usually hampered by selection of more educated parents. To prevent such bias, we used unselected nationwide Geographical Information System (GIS)-based registry data, to investigate the influence of socio-economic disparities on the risk of childhood cancer.

METHODS

The Geocap study included all French residents diagnosed with cancer aged up to 15 years over the period 2002-2010 (15 111 cases) and 45 000 contemporaneous controls representative of the childhood population. Area socio-economic characteristics used to calculate the European Deprivation Index (EDI) were based on census data collected on the fine scale of the Merged Islet for Statistical Information (IRIS).

RESULTS

Overall, the risk of acute lymphoblastic leukaemia (ALL) was lower in the most deprived quintile than in the other quintiles of EDI (OR_Q5vs<Q5 0.80 (95% confidence interval (CI) 0.73, 0.88)). The odds ratio for all the other cancers taken together was close to the null (OR_Q5vs<Q5 0.99 (95% CI 0.94, 1.04)).

CONCLUSION

Living in the most deprived areas was inversely associated with the risk of ALL in childhood. There was no indication that the risk of childhood cancer of any site could be increased by deprivation. Life style or environmental factors potentially underlying the association need further investigation.

The Role of Childhood Infections and Immunizations on Childhood Rhabdomyosarcoma: A Report From the Children's Oncology Group

BACKGROUND

Rhabdomyosarcoma (RMS) is a rare, highly malignant tumor arising from primitive mesenchymal cells that differentiate into skeletal muscle. Relatively little is known about RMS susceptibility. Based on growing evidence regarding the role of early immunologic challenges on RMS development, we evaluated the role of infections and immunizations on this clinically significant pediatric malignancy.

PROCEDURE

RMS cases (n = 322) were enrolled from the third trial coordinated by the Intergroup Rhabdomyosarcoma Study Group. Population-based controls (n = 322) were pair matched to cases on race, sex, and age. The following immunizations were assessed: diphtheria, pertussis, and tetanus (DPT); measles, mumps, and rubella; and oral polio vaccine. We also evaluated if immunizations were complete versus incomplete. We examined selected infections including chickenpox, mumps, pneumonia, scarlet fever, rubella, rubeola, pertussis, mononucleosis, and lung infections. Conditional logistic regression models were used to calculate an odds ratio (OR) and 95% confidence interval (CI) for each exposure, adjusted for maternal education and total annual income.

RESULTS

Incomplete immunization schedules (OR = 5.30, 95% CI: 2.47-11.33) and incomplete DPT immunization (OR = 1.56, 95% CI: 1.06-2.29) were positively associated with childhood RMS. However, infections did not appear to be associated with childhood RMS.

CONCLUSIONS

This is the largest study of RMS to date demonstrating a possible protective effect of immunizations against the development of childhood RMS. Further studies are needed to validate our findings. Our findings add to the growing body of literature, suggesting a protective role of routine vaccinations in childhood cancer and specifically in childhood RMS.

Breastfeeding, Other Early Life Exposures and Childhood Leukemia and Lymphoma

Childhood cancer incidence increases and although rare, it is a leading cause of mortality. Leukemia and lymphoma comprise 40% of all cancers in children but little is known of their etiology. In this study, we examined the associations of breastfeeding and other early life exposures with childhood leukemia and lymphoma. A population-based case-control study carried out in 2011-2013 comprised mothers of 190 incidents (2005-2013) of leukemia/lymphoma cases aged 1-19 yr at diagnosis and 384 population-based controls. Interviews based on a computerized structured questionnaire were conducted with the mothers. Multivariate logistic regression models adjusted for potential confounders assessed the association between breastfeeding patterns and childhood leukemia/lymphoma. Ever breastfeeding category was associated with a 64% decreased risk for childhood leukemia/lymphoma lsqb;odds ratio (OR) = 0.36, 95% confidence interval (CI): 0.22, 0.60lrqb; and similar trends, with a dose-response effect, were observed for any breastfeeding (exclusive and/or partial) category for 6, 12, and 18+ mo. Other infant exposures associated with cancer risk were child iron supplementation (OR = 0.39, 95% CI: 0.26, 0.59), pet ownership (OR = 0.50, 95% CI: 0.33, 0.78), paternal smoking (OR = 1.93, 95% CI: 1.18, 3.15), and having older siblings (OR = 1.18, 95% CI: 1.05, 1.33). Breastfeeding-a controllable and modifiable exposure-is inversely associated with risk for childhood leukemia and lymphoma with a dose-response effect.

Caesarean delivery and risk of childhood leukaemia: a pooled analysis from the Childhood Leukemia International Consortium (CLIC)

BACKGROUND

Results from case-control studies have shown an increased risk of acute lymphoblastic leukaemia (ALL) in young children born by caesarean delivery, and prelabour caesarean delivery in particular; however, an association of method of delivery with childhood leukaemia subtypes has yet to be established. We therefore did a pooled analysis of data to investigate the association between childhood leukaemia and caesarean delivery.

METHODS

We pooled data from 13 case-control studies from the Childhood Leukemia International Consortium done in nine countries (Canada, Costa Rica, Egypt, France, Germany, Greece, Italy, New Zealand, and the USA) for births from 1970-2013. We analysed caesarean delivery overall and by indications that probably resulted in prelabour caesarean delivery or emergency caesarean delivery. We used multivariable logistic regression models, adjusted for child's birthweight, sex, age, ethnic origin, parental education, maternal age, and study, to estimate odds ratios (ORs) and 95% CIs for the risk of ALL and acute myeloid leukaemia (AML) in children aged 0-14 years at diagnosis.

FINDINGS

The studies provided data for 8780 ALL cases, 1332 AML cases, and 23 459 controls, of which the birth delivery method was known for 8655 (99%) ALL cases, 1292 (97%) AML cases, and 23 351 (>99%) controls. Indications for caesarean delivery were available in four studies (there were caesarean deliveries for 1061 of 4313 ALL cases, 138 of 664 AML cases, and 1401 of 5884 controls). The OR for all indications of caesarean delivery and ALL was 1·06 (95% CI 0·99-1·13), and was significant for prelabour caesarean delivery and ALL (1·23 [1·04-1·47]; p=0·018). Emergency caesarean delivery was not associated with ALL (OR 1·02 [95% CI 0·81-1·30]). AML was not associated with caesarean delivery (all indications OR 0·99 [95% CI 0·84-1·17]; prelabour caesarean delivery 0·83 [0·54-1·26]; and emergency caesarean delivery 1·05 [0·63-1·77]).

INTERPRETATION

Our results suggest an increased risk of childhood ALL after prelabour caesarean delivery. If this association is causal, maladaptive immune activation due to an absence of stress response before birth in children born by prelabour caesarean delivery could be considered as a potential mechanism.

FUNDING

National Cancer Institute.

A variant at 9p21.3 functionally implicates CDKN2B in paediatric B-cell precursor acute lymphoblastic leukaemia aetiology

Paediatric B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) is the most common cancer of childhood, yet little is known about BCP-ALL predisposition. In this study, in 2,187 cases of European ancestry and 5,543 controls, we discover and replicate a locus indexed by rs77728904 at 9p21.3 associated with BCP-ALL susceptibility (Pcombined=3.32 × 10(-15), OR=1.72) and independent from rs3731217, the previously reported ALL-associated variant in this region. Of correlated SNPs tagged by this locus, only rs662463 is significant in African Americans, suggesting it is a plausible causative variant. Functional analysis shows that rs662463 is a cis-eQTL for CDKN2B, with the risk allele associated with lower expression, and suggests that rs662463 influences BCP-ALL risk by regulating CDKN2B expression through CEBPB signalling. Functional analysis of rs3731217 suggests it is associated with BCP-ALL by acting within a splicing regulatory element determining CDKN2A exon 3 usage (P=0.01). These findings provide new insights into the critical role of the CDKN2 locus in BCP-ALL aetiology.

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.

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.

Childhood acute lymphoblastic leukemia and indicators of early immune stimulation: a Childhood Leukemia International Consortium study

The associations between childhood acute lymphoblastic leukemia (ALL) and several proxies of early stimulation of the immune system, that is, day-care center attendance, birth order, maternally reported common infections in infancy, and breastfeeding, were investigated by using data from 11 case-control studies participating in the Childhood Leukemia International Consortium (enrollment period: 1980-2010). The sample included 7,399 ALL cases and 11,181 controls aged 2-14 years. The data were collected by questionnaires administered to the parents. Pooled odds ratios and 95% confidence intervals were estimated by unconditional logistic regression adjusted for age, sex, study, maternal education, and maternal age. Day-care center attendance in the first year of life was associated with a reduced risk of ALL (odds ratio = 0.77, 95% confidence interval: 0.71, 0.84), with a marked inverse trend with earlier age at start (P < 0.0001). An inverse association was also observed with breastfeeding duration of 6 months or more (odds ratio = 0.86, 95% confidence interval: 0.79, 0.94). No significant relationship with a history of common infections in infancy was observed even though the odds ratio was less than 1 for more than 3 infections. The findings of this large pooled analysis reinforce the hypothesis that day-care center attendance in infancy and prolonged breastfeeding are associated with a decreased risk of ALL.

Association of genetic variation in IKZF1, ARID5B, and CEBPE and surrogates for early-life infections with the risk of acute lymphoblastic leukemia in Hispanic children

BACKGROUND

Genome-wide association studies focusing on European-ancestry populations have identified ALL risk loci on IKZF1, ARID5B, and CEBPE. To capture the impacts of these genes on ALL risk in the California Hispanic population, we comprehensively assessed the variation within the genes and further assessed the joint effects between the genetic variation and surrogates for early-life infections (the presence of older siblings, daycare attendance, and ear infections).

METHODS

Genotypic data for 323 Hispanic ALL cases and 454 controls from the California Childhood Leukemia Study were generated using Illumina OmniExpress v1 platform. Logistic regression assuming a log-additive model estimated odds ratios (OR) associated with each SNP, adjusted for age, sex, and the first five principal components. In addition, we examined potential interactions between six ALL risk alleles and surrogates for early-life infections using logistic regression models that included an interaction term.

RESULTS

Significant associations between genotypes at IKZF1, ARID5B, and CEBPE and ALL risk were identified: rs7780012, OR 0.50, 95% confidence interval (CI) 0.35-0.71 (p = 0.004); rs7089424, OR 2.12, 95% CI 1.70-2.65 (p = 1.16 × 10(-9)); rs4982731, OR 1.69, 95% CI 1.37-2.08 (p = 2.35 × 10(-6)), respectively. Evidence for multiplicative interactions between genetic variants and surrogates for early-life infections with ALL risk was not observed.

CONCLUSIONS

Consistent with findings in non-Hispanic White population, our study showed that variants within IKZF1, ARID5B, and CEBPE were associated with increased ALL risk, and the effects for ARID5B and CEBPE were most prominent in the high-hyperdiploid ALL subtype in the California Hispanic population. Results implicate the ARID5B, CEBPE, and IKZF1 genes in the pathogenesis of childhood ALL.

ARID5B, IKZF1 and non-genetic factors in the etiology of childhood acute lymphoblastic leukemia: the ESCALE study

Genome-wide association studies (GWAS) have identified that frequent polymorphisms in ARID5B and IKZF1, two genes involved in lymphoid differentiation, increase the risk of childhood acute lymphoblastic leukemia (ALL). These findings markedly modified the current field of research on the etiology of ALL. In this new context, the present exploratory study investigated the possible interactions between these at-risk alleles and the non-genetic suspected ALL risk factors that were of sufficient prevalence in the French ESCALE study: maternal use of home insecticides during pregnancy, preconception paternal smoking, and some proxies for early immune modulation, i.e. breastfeeding, history of common infections before age one year, and birth order. The analyses were based on 434 ALL cases and 442 controls of European origin, drawn from the nationwide population-based case-control study ESCALE. Information on non-genetic factors was obtained by standardized telephone interview. Interactions between rs10740055 in ARID5B or rs4132601 in IKZF1 and each of the suspected non-genetic factors were tested, with the SNPs coded as counts of minor alleles (trend variable). Statistical interactions were observed between rs4132601 and maternal insecticide use (p = 0.012), breastfeeding p = 0.017) and repeated early common infections (p = 0.0070), with allelic odds ratios (OR) which were only increased among the children not exposed to insecticides (OR = 1.8, 95%CI: 1.3, 2.4), those who had been breastfed (OR = 1.8, 95%CI: 1.3, 2.5) and those who had had repeated early common infections (OR = 2.4, 95%CI: 1.5, 3.8). The allelic ORs were close to one among children exposed to insecticides, who had not been breastfed and who had had no or few common infections. Repeated early common infections interacted with rs10740055 (p = 0.018) in the case-only design. Further studies are needed to evaluate whether these observations of a modification of the effect of the at-risk alleles by non-genetic factors are chance findings or reflect true underlying mechanisms.