Maternal and birth characteristics in relation to childhood leukaemia

Risk of childhood neoplasms related to neonatal phototherapy- a systematic review and meta-analysis

CONTEXT

Observational studies have shown conflicting results as to whether exposure to neonatal phototherapy is associated with increased rates of childhood cancer.

OBJECTIVE

To describe the rates of childhood neoplasms and cancer after neonatal phototherapy.

DATA SOURCES

The CENTRAL, PubMed, Scopus, and Web of Science databases.

STUDY SELECTION

Observational studies regardless of design were included.

DATA EXTRACTION

The data were extracted by one author and validated by another. The risk-of-bias assessment was performed using the ROBINS-E and Joanna Briggs Institute critical appraisal tools.

RESULTS

Six cohort and 10 case-control studies were included. The overall risk of bias was high in seven and low in nine studies. In cohort studies, the odds ratio (OR) was increased for hematopoietic cancer (1.44; confidence interval [CI]: 1.16-1.80) and solid tumors (OR: 1.18; CI: 1.00-1.40). In case-control studies, the OR was 1.63 (CI: 0.99-2.67) for hematopoietic cancers and 1.18 (CI: 1.04-1.34) for solid tumors.

CONCLUSIONS

Children with a history of neonatal phototherapy had increased risk of hematopoietic cancer and solid tumors. The evidence quality was limited due to the high risk of bias and potential residual confounding.

IMPACT STATEMENT

Exposure to neonatal phototherapy increased later risk of hematopoietic cancer and solid tumors. This is the most comprehensive study on the association between phototherapy and cancer, but the evidence quality was limited due risk of bias and residual confounding. Future large scale well conducted studies are still needed to better estimate the association and.

Association between birth weight and risk of nonneurological childhood cancers: a systematic review and meta-analysis

OBJECTIVES

This systematic review aims to synthesize the available literature to determine the association between birthweight and the risk of nonneurological childhood cancers.

METHODS

We conducted a systematic search of PubMed, Web of Science, and Scopus databases up to May 2023 to identify observational studies. Heterogeneity between studies was evaluated using the I2 statistics. Publication bias was assessed using Begg and Egger tests. We calculated the odds ratio (OR) or risk ratio (RR) with a 95% confidence interval (CI) using a random-effects model.

RESULTS

Of 11 034 studies retrieved from the search, 56 studies (including 10 568 091 participants) were eligible. The ORs (95% CI) of low (<2500 g) versus normal birthweight (2500-4000 g) and childhood cancers were as follows: leukemia, 0.92 (0.77-1.11); acute lymphoblastic leukemia, 0.82 (0.72-0.94); acute myeloid leukemia, 0.98 (0.77-1.24); lymphoma, 0.99 (0.47-2.10); Hodgkin, 0.79 (0.61-1.03); non-Hodgkin, 0.85 (0.60-1.20); neuroblastoma, 1.34 (1.14-1.58); retinoblastoma, 0.95 (0.68-1.32); rhabdomyosarcoma, 0.86 (0.61-1.20); embryonal, 0.97 (0.66-1.43); alveolar, 1.92 (0.43-8.51); and Wilms tumor, 1.01 (0.83-1.24). The ORs (95% CI) of high (>4000 g) versus normal birthweight and childhood cancers were as follows: leukemia, 1.30 (1.18-1.42); acute lymphoblastic leukemia, 1.27 (1.16-1.39); acute myeloid leukemia, 1.13 (0.98-1.30); lymphoma, 1.69 (0.72-3.94); Hodgkin, 1.22 (1.02-1.46); non-Hodgkin, 1.22 (0.80-1.86); neuroblastoma, 1.20 (1.02-1.41); retinoblastoma, 1.17 (0.93-1.48); rhabdomyosarcoma, 1.07 (0.90-1.27); embryonal, 1.22 (1.00-1.49); alveolar, 1.02 (0.46-2.27); and Wilms tumor, 1.49 (1.34-1.67).

CONCLUSION

This meta-analysis identified high birth weight as a potential risk factor for some childhood cancers, while low birth weight might be protective against a few.

The Relationship Between Gestational Diabetes and the Risk of Cancer: A Systematic Review

Gestational diabetes mellitus (GDM) is one of the most common endocrine disorders to occur during pregnancy due to the increase in circulating human placental lactogen (hPL) and possible beta-cell sensitivity. While GDM can be managed either with diet and exercise or pharmacological interventions, it is associated with significant maternal and neonatal complications. Maternal complications include short- and long-term conditions such as pre-eclampsia, preterm birth, arrest of labor, future development of type 2 diabetes mellitus (T2DM), and cardiovascular disorders. Neonates can develop hypoglycemia and hypocalcemia and have a large gestational age (LGA). New research has also highlighted another possible long-term complication for both mothers and offspring, which is the development of cancer. Cancer has various types of progression, but most cause systemic symptoms leading to a reduced quality of life. Cancer can be terminal and can affect the majority of the population; thus, significant effort is being employed to try and reduce its occurrence. This systematic review was conducted with adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using PubMed, ScienceDirect, and ProQuest databases. Initially, 136,019 publications were identified. Through the screening process, a total of 27 publications were finalized within the scope of this paper. Most studies observing maternal cancer with a history of GDM found that there was an association between the increased risk of cancer and GDM. Specifically, these studies identified the association of GDM with breast, ovarian, cervical, and uterine cancer, as well as other non-reproductive organs such as the thyroid and pancreas. Cancer development in the offspring also presented an association with mothers who developed GDM. The most prevalent cancer evaluated was leukemia, and it was specifically associated with a maternal history of GDM. With the consistent rise in the incidence of cancer, any attempts to reduce its development are imperative to assess. While GDM is essentially a temporary condition that resolves following pregnancy in most patients, the possibility of contributing to future conditions years after its occurrence creates a sense of urgency and necessity to reduce the incidence of GDM. Researchers should be able to identify other unknown biomarkers that contribute to the development of cancer in mothers who experienced GDM as well as their infants.

Association between neonatal phototherapy and future cancer: an updated systematic review and meta-analysis

Phototherapy is the main treatment of neonatal hyperbilirubinemia to prevent encephalopathy. It is generally believed to be safe; however, some studies have shown it might be associated with cancer development. In this systematic review and meta-analysis, we aimed to assess the effect of neonatal phototherapy on future cancer risk. A systematic search in 13 databases was conducted in December 2018 and updated in August 2022 to identify studies that report cancer development after exposure to phototherapy. Throughout the study period, regular manual searches were also conducted to include new studies. A meta-analysis using R programming language was done in which the odds ratios (ORs) with 95% confidence intervals (CIs) were estimated and pooled using the reported adjusted and unadjusted data. Fifteen studies were included. A statistically significant association was detected between neonatal phototherapy and any type of cancer (OR 1.24; 95% CI 1.1, 1.4), any hematopoietic cancer (OR 1.49; 95% CI 1.17, 1.91), any leukemia (OR 1.35; 95% CI 1.08, 1.67), and myeloid leukemia (OR 2.86; 95% CI 1.4, 5.84). The other investigated cancers (lymphoid leukemia, Hodgkin's lymphoma, kidney cancer, nervous system cancer, and skin cancer) were not associated with phototherapy.  Conclusions: Phototherapy may carry a possible risk of future cancers. Future research is needed to quantify the magnitude of the cancer risk. These future studies should consider predictors of preterm birth or exclude premature babies from their analysis. What is Known • There were various reports about the possible association between phototherapy in neonates and the increased risk of cancer in the future. What is New • A statistically significant association between phototherapy and various hematopoietic cancers (especially myeloid leukemia) was recorded. • The effect of the duration of phototherapy on the increased risk of hematopoietic cancers is yet unclear.

Blue-Green (~480 nm) versus Blue (~460 nm) Light for Newborn Phototherapy-Safety Considerations

We have previously shown that the phototherapy of hyperbilirubinemic neonates using blue-green LED light with a peak wavelength of ~478 nm is 31% more efficient for removing unconjugated bilirubin from circulation than blue LED light with a peak wavelength of ~452 nm. Based on these results, we recommended that the phototherapy of hyperbilirubinemic newborns be practiced with light of ~480 nm. Aim: Identify and discuss the most prominent potential changes that have been observed in the health effects of phototherapy using either blue fluorescent- or blue LED light and speculate on the expected effects of changing to blue-green LED light phototherapy. Search the phototherapy literature using the terms neonate, hyperbilirubinemia, and phototherapy in the PubMed and Embase databases. Transitioning from blue fluorescent light to blue-green LED light will expose neonates to less light in the 400-450 nm spectral range, potentially leading to less photo-oxidation and geno-/cytotoxicity, reduced risk of cancer, and decreased mortality in extremely low-birthweight neonates. The riboflavin level may decline, and the increased production and retention of bronze pigments may occur in predisposed neonates due to enhanced lumirubin formation. The production of pre-inflammatory cytokines may rise. Hemodynamic responses and transepidermal water loss are less likely to occur. The risk of hyperthermia may decrease with the use of blue-green LED light and the risk of hypothermia may increase. Parent-neonate attachment and breastfeeding will be positively affected because of the shortened duration of phototherapy. The latter may also lead to a significant reduction in the cost of phototherapy procedures as well as the hospitalization process.

Incorporation of DNA methylation quantitative trait loci (mQTLs) in epigenome-wide association analysis: application to birthweight effects in neonatal whole blood

BACKGROUND

Epigenome-wide association studies (EWAS) have helped to define the associations between DNA methylation and many clinicopathologic and developmental traits. Since DNA methylation is affected by genetic variation at certain loci, EWAS associations may be potentially influenced by genetic effects. However, a formal assessment of the value of incorporating genetic variation in EWAS evaluations is lacking especially for multiethnic populations.

METHODS

Using single nucleotide polymorphism (SNP) from Illumina Omni Express or Affymetrix PMDA arrays and DNA methylation data from the Illumina 450 K or EPIC array from 1638 newborns of diverse genetic ancestries, we generated DNA methylation quantitative trait loci (mQTL) databases for both array types. We then investigated associations between neonatal DNA methylation and birthweight (incorporating gestational age) using EWAS modeling, and reported how EWAS results were influenced by controlling for mQTLs.

RESULTS

For CpGs on the 450 K array, an average of 15.4% CpGs were assigned as mQTLs, while on the EPIC array, 23.0% CpGs were matched to mQTLs (adjusted P value < 0.05). The CpGs associated with SNPs were enriched in the CpG island shore regions. Correcting for mQTLs in the EWAS model for birthweight helped to increase significance levels for top hits. For CpGs overlapping genes associated with birthweight-related pathways (nutrition metabolism, biosynthesis, for example), accounting for mQTLs changed their regression coefficients more dramatically (> 20%) than for other random CpGs.

CONCLUSION

DNA methylation levels at circa 20% CpGs in the genome were affected by common SNP genotypes. EWAS model fit significantly improved when taking these genetic effects into consideration. Genetic effects were stronger on CpGs overlapping genetic elements associated with control of gene expression.

Maternal BMI, Diabetes, and Gestational Weight Gain and Risk for Pediatric Cancer in Offspring: A Systematic Review and Meta-Analysis

Background

Pediatric cancer incidence has steadily increased concurrent with rising adult obesity, but associations between maternal obesity and associated comorbidities and pediatric cancer risk remain understudied. We aimed to quantitatively characterize associations of pediatric cancer risk with maternal prepregnancy body mass index (BMI), gestational weight gain, and maternal diabetes.

Methods

We performed a comprehensive and systematic literature search in Ovid and EMBASE from their inception to March 15, 2021. Eligible studies reported risk estimates and sample sizes and provided sufficient description of outcome and exposure ascertainment. Random effects models were used to estimate pooled effects.

Results

Thirty-four studies were included in the analysis. Prepregnancy BMI was positively associated with leukemia risk in offspring (odds ratio [OR] per 5-unit BMI increase =1.07, 95% confidence intervals [CI] = 1.04 to 1.11; I² = 0.0%). Any maternal diabetes was positively associated with acute lymphoblastic leukemia risk (OR = 1.46, 95% CI = 1.28 to 1.67; I² = 0.0%), even after restricting to birthweight-adjusted analyses (OR = 1.74, 95% CI = 1.29 to 2.34; I² = 0.0%), and inversely associated with risk of central nervous system tumors (OR = 0.73, 95% CI = 0.55 to 0.97; I² = 0.0%). Pregestational diabetes (OR = 1.57, 95% CI = 1.11 to 2.24; I² = 26.8%) and gestational diabetes (OR = 1.40, 95% CI = 1.12 to 1.75; I² = 0.0%) were also positively associated with acute lymphoblastic leukemia risk. No statistically significant associations were observed for gestational weight gain.

Conclusions

Maternal obesity and diabetes may be etiologically linked to pediatric cancer, particularly leukemia and central nervous system tumors. Our findings support weight management and glycemic control as important components of maternal and offspring health. Further validation is warranted.

Réponse à un schéma chimiothérapeutique administré à des enfants atteints de LAL à cellules pré-B à risque élevé selon le protocole COG

Objectif

La présente étude a pour but d'examiner la réponse à un schéma chimiothérapeutique administré à des enfants atteints de LAL à cellules pré-B à risque élevé selon le protocole COG.

Méthode

L'étude transversale porte sur 55 enfants traités selon le protocole du groupe d'oncologie pédiatrique (mieux connu sous le nom de Children's Oncology Group ou COG), de septembre 2010 à février 2015, et évalue les résultats du schéma chimiothérapeutique.

Résultats

Durant la première semaine suivant le traitement, le taux de rétablissement complet a été de 76,4 %. Les taux de survie après trois ans et cinq ans étaient respectivement de 85,5 % et de 81 %. Le taux de rechute après le premier épisode de rémission a été de 20 % et le taux de mortalité consécutif à cette rechute a été de 50 %. Trente pour cent de l'ensemble des décès ont eu lieu durant la période d'induction. Dans tous les cas, une septicémie en est la cause.

Conclusion

Les résultats indiquent que le taux de survie a augmenté. Il est donc possible d'améliorer le taux de survie en optant pour le protocole COG et en contrôlant les infections chez les patients, et ce, sans égard au groupe de risque.

The outcome of chemotherapeutic regimen by high-risk pre-B-cell protocol in ALL children

Objective

The aim of this study was to investigate the outcome of chemotherapeutic regimen by high-risk pre-B-cell potocol in ALL children.

Methods

The cross-sectional study was conducted on 55 children who were treated with the Children Oncology Group (COG) protocol from September 2010 to February 2015 to evaluate the chemotherapeutic regimen results.

Results

There was a complete recovery rate of 76.4% during the first week after treatment. Three-year overall survival was 85.5% and five-year overall survival was 81%. Relapse rate after first remission was 20% and death after relapse was 50%. Thirty percent of total deaths were at the induction period. All of the deceased cases died due to sepsis.

Conclusion

Results showed that the survival rate increased. By choosing the COG protocol and by controlling infection in patients without considering the risk group we can improve survival rates.

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.

Maternal diabetes and risk of childhood malignancies in the offspring: a systematic review and meta-analysis of observational studies

AIMS

Diabetes mellitus (DM) is widely recognized as a risk factor for diverse cancers in adults. However, the association between maternal diabetes and risk of childhood cancer in the offspring has so far not been well studied. We thus conducted a meta-analysis to evaluate the role of maternal diabetes on the risk of childhood cancer.

METHODS

We performed a comprehensive literature search to identify eligible studies published up to June 20, 2020, including the PubMed, Web of science and Embase databases. Summary odds ratios (OR) and 95% confidence intervals (CI) were computed using a random-effects model (I² ≥ 25%) or a fixed-effect model (I² < 25%).

RESULTS

Totally, sixteen case-control and six cohort studies on the risk of childhood cancer associated with maternal diabetes were included. Overall, children of diabetic women had a significantly increased risk in childhood malignancy (OR, 1.30; 95% CI, 1.10-1.53). Notably, a significantly elevated risk of childhood cancer in the offspring was found for women with pre-existing diabetes (OR, 1.41; 95% CI, 1.17-1.70), but not for women with gestational diabetes mellitus (GDM) (OR, 1.10; 95% CI, 0.94-1.28). For site-specific cancers, maternal diabetes was associated with a higher risk of leukemia in offspring (OR, 1.30; 95% CI, 1.15-1.48), especially for acute lymphoblastic leukemia (OR, 1.44; 95% CI, 1.27-1.64). However, no significant associations were observed between maternal diabetes and the risk of lymphomas and retinoblastoma.

CONCLUSIONS

Our meta-analysis indicates that maternal diabetes is associated with an increased risk of childhood cancer in the offspring, particularly for acute lymphoblastic leukemia. Future study should investigate the underlying biological mechanisms behind the association.

The Association Between High Birth Weight and Long-Term Outcomes-Implications for Assisted Reproductive Technologies: A Systematic Review and Meta-Analysis

Background: Studies have shown that the prevalence of children born with high birth weight or large for gestational age (LGA) is increasing. This is true for spontaneous pregnancies; however, children born after frozen embryo transfer (FET) as part of assisted reproductive technology (ART) also have an elevated risk. In recent years, the practice of FET has increased rapidly and while the perinatal and obstetric risks are well-studied, less is known about the long-term health consequences. Objective: The aim of this systematic review was to describe the association between high birth weight and LGA on long-term child outcomes. Data Sources: PubMed, Scopus, and Web of Science were searched up to January 2021. Exposure included high birth weight and LGA. Long-term outcome variables included malignancies, psychiatric disorders, cardiovascular disease, and diabetes. Study Selection: Original studies published in English or Scandinavian languages were included. Studies with a control group were included while studies published as abstracts and case reports were excluded. Data Extraction: The methodological quality, in terms of risk of bias, was assessed by pairs of reviewers. Robins-I (www.methods.cochrane.org) was used for risk of bias assessment in original articles. For systematic reviews, AMSTAR (www.amstar.ca) was used. For certainty of evidence, we used the GRADE system. The systematic review followed PRISMA guidelines. When possible, meta-analyses were performed. Results: The search included 11,767 articles out of which 173 met the inclusion criteria and were included in the qualitative analysis, while 63 were included in quantitative synthesis (meta-analyses). High birth weight and/or LGA was associated with low to moderately elevated risks for certain malignancies in childhood, breast cancer, several psychiatric disorders, hypertension in childhood, and type 1 and 2 diabetes. Conclusions: Although the increased risks for adverse outcome in offspring associated with high birth weight and LGA represent serious health effects in childhood and in adulthood, the size of these effects seems moderate. The identified risk association should, however, be taken into account in decisions concerning fresh and frozen ART cycles and is of general importance in view of the increasing prevalence in high birthweight babies.

Birth Weight and Subsequent Risk of Total Leukemia and Acute Leukemia: A Systematic Review and Meta-Analysis

Objective: Birth weight, an important indicator of fetal nutrition and degree of development, may affect the risk of subsequent leukemia. At present, little is known about the effect of birth weight on acute myeloid leukemia (AML) and whether there is a dose-dependent relationship of birth weight with acute lymphoid leukemia (ALL) and AML. To address these questions, the present work aimed to systematically investigate the relationship between birth weight and the risk of subsequent leukemia based on the current epidemiological studies Methods: Relevant studies were systematically retrieved from electronic databases PubMed, Embase, and Cochrane Library, from inception to May 15th, 2021. Finally, 28 studies (including 21 case-control studies and 7 cohort studies) were included for the final meta-analysis. Results in cohort studies were performed by risk ratios (RRs), while those in case-control studies by odds ratios (ORs), and all results were assessed by adopting the random-effect model. Besides, a dose-dependent analysis was conducted based on the cohort studies. Results: Compared with the population with normal birth weight (NBW), the population with high birth weight (HBW) might have an increased risk of leukemia (OR 1.33, 95%CI 1.20-1.49; I ² 0%). Meanwhile, low birth weight (LBW) was associated with a decreased risk of ALL, as evidenced from the pooled analysis of case-control studies (OR 0.83, 95% CI 0.75-0.92; I ² 23.3%). However, relative to NBW population, the HBW population might have an increased risk of ALL (OR 1.28, 95% CI 1.20-1.35; I ² 7%). There was no obvious evidence supporting the relationship between LBW and the risk of AML from the pooled analysis of case-control studies (OR, 1.11 95% CI 0.87-1.42; I ² 31.7%). Conclusions: Overall, in children and young adults, HBW population may be associated with the risks of subsequent leukemia and AML relative to NBW population, but the supporting dose-dependent evidence is lacking. In addition, compared with NBW population, there is stronger evidence supporting a significantly increased risk of subsequent ALL in HBW population, and a decreased risk in LBW population in a dose-dependent manner. More prospective studies with large samples are warranted in the future to validate and complement these findings.

Caesarean sections, prenatal and postnatal conditions and childhood acute lymphoblastic leukaemia: A case-control study in the State of São Paulo, Brazil

INTRODUCTION

Brazil has high rates of caesarean sections, which has been suggested as a risk factor for acute lymphoblastic leukaemia (ALL). In addition, some pre- and postnatal conditions have been identified as relevant in the etiology of ALL.

OBJECTIVES

Investigate the association of caesarean sections, pre- and postnatal conditions with childhood ALL in the State of São Paulo.

METHODS

Population-based case-control study including children that are below10 years old. Information on study variables was obtained through face to face interviews, through a questionnaire, and the State of São Paulo Declarations of Live Births database. The conditional and unconditional logistic regression approaches were used to calculate the odds ratio (OR) of the associations between caesarean sections, pre- and postnatal conditions with ALL, and 95 % confidence intervals (95 % CI).

RESULTS

We observed a weak and non-statistically significant risk for ALL among children exposed to caesarean sections (unconditional logistic regression OR 1.08; 95 % CI 0.70-1.66; conditional logistic regression OR 1.21; 95 % CI 0.72-2.02), but among children under 3 years old and born through a caesarean sections, the risk of ALL was greater (unconditional logistic regression OR 1.70; 95 % CI 0.69-4.21). A negative association for ALL was observed among children with mothers who reported 12 years of schooling or more (unconditional logistic regression OR 0.34; 95 % CI 0.16-0.69).

CONCLUSIONS

We found a tenuous suggestive association between caesarean sections and childhood ALL. The mother's high level of education showed an inverse association with ALL.

Cesarean section and risk of childhood leukemia: a systematic review and meta-analysis

BACKGROUND

A large number of studies pointed that being delivered by cesarean section (CS) would affect the health outcomes of offspring, however, whether CS would affect the risk of childhood leukemia remained uncertain. This study conducted a meta-analysis to quantitatively evaluate whether being delivered by CS would influence the onset of childhood leukemia.

METHODS

PubMed, Embase and Web of Science databases were searched from 3rd June, 1950 to 13th October, 2019 to identify the literature, which examined the relationship between CS and childhood leukemia. This study used Newcastle-Ottawa Scale to assess the quality of literature. Subgroup analyses were conducted on region, mode of delivery, design of the study and number of confounders adjusted. Egger's test and Begg's test were performed to evaluate possible publication bias.

RESULTS

The pooled odds ratio (OR) estimates illustrated that children delivered by CS had a higher risk of developing leukemia [OR 1.10, 95% confidence interval (CI) 1.04-1.17, P = 0.002] and lymphoblastic leukemia (OR 1.12, 95% CI 1.03-1.23, P = 0.009), while a significant association for myeloid leukemia was not observed (OR 1.05, 95% CI 0.92-1.20, P = 0.451). Results of subgroup analyses indicated that elective CS would increase the risk of childhood lymphoblastic leukemia (OR 1.16, 95% CI 1.06-1.27, P = 0.002). However, a statistical relationship between emergency CS and lymphoblastic leukemia was not observed (OR 1.07, 95% CI 0.93-1.23, P = 0.364).

CONCLUSIONS

CS would increase the risk of childhood lymphoblastic leukemia. It is worth noting that subgroup analyses shows that elective CS rather than emergency CS increases the risk of lymphoblastic leukemia in offspring.

Birthweight and all-cause mortality after childhood and adolescent leukemia: a cohort of children with leukemia from Denmark, Norway, Sweden, and Washington State

Background: High birthweight may predispose children to acute lymphoid leukemia, whereas low birthweight is associated with childhood morbidity and mortality. Low and high birthweight have been inconsistently associated with mortality in children with leukemia.Material and methods: In a cohort of childhood and adolescent leukemia (0-19 years) patients from registries in Denmark, Norway, Sweden, and Washington State in the United States (1967-2015), five-year all-cause mortality was assessed by birthweight and other measures of fetal growth using the cumulative incidence function and Cox regression with adjustment for sex, diagnosis year, country, the presence of Down's syndrome or other malformations, and type of leukemia.Results: Among 7148 children and adolescents with leukemia (55% male), 4.6% were low (<2500 g) and 19% were high (≥4000 g) birthweight. Compared with average weight, hazard ratios (HRs) of death associated with low birthweight varied by age at leukemia diagnosis: 1.5 (95% confidence interval (CI): 0.7, 3.2) for patients 0-1 year old, 1.6 (95% CI: 1.0, 2.6) for >1-2 years old; 1.0 (95% CI: 0.6, 1.5) for 3-8 years old; 1.0 (95% CI: 0.6, 1.8) for 9-13 years old; and 1.2 (95% CI: 0.7, 2.1) for 14-19 years old, and were similar for size for gestational age and Ponderal index. In analyses restricted to children born full term (37-41 weeks of gestation), results were only slightly attenuated but risk was markedly increased for infants aged ≤1 year (HR for low birthweight = 3.2, 95% CI: 1.2, 8.8).Conclusion: This cohort study does not suggest that low birthweight or SGA is associated with increased five-year all-cause mortality risk among children with any type of childhood leukemia or acute lymphoblastic leukemia, specifically, beyond infancy.

Paediatric acute lymphoblastic leukaemia and caesarean section: A report from the United Kingdom Childhood Cancer Study (UKCCS)

BACKGROUND

Reports have suggested that children born by caesarean initiated before labour onset may be at increased risk of developing acute lymphoblastic leukaemia (ALL). However, with most data being derived from case-control study interviews, information on the underpinning reasons for caesarean section is sparse, and evidence is conflicting.

OBJECTIVES

Use clinical records compiled at the time of delivery to investigate the association between childhood ALL and caesarean delivery; examining timing in relation to labour onset, and reasons for the procedure.

METHODS

Data are from the UK Childhood Cancer Study, a population-based case-control study conducted in the 1990s, when caesarean section rates were relatively low, in England, Scotland, and Wales. Children with ALL were individually matched to two controls on sex, date of birth, and region of residence. Information on mode of delivery and complications was abstracted from obstetric records. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression models adjusted for matching variables and relevant covariates.

RESULTS

Around 75% of the 1034 cases and 1914 controls were born through unassisted vaginal delivery. Caesarean delivery was as frequent in cases and controls (OR 1.07, 95% CI 0.84, 1.36). No association was observed between ALL and caesarean delivery either during or before labour, with adjusted ORs of 1.08 (95% CI 0.78, 1.48) and 1.09 (95% CI 0.78, 1.53), respectively. For B-cell ALL, the ORs were 1.14 (95% CI 0.81, 1.59) for caesarean during labour and 1.21 (95% CI 0.85, 1.72) for prelabour. The underpinning reasons for caesarean delivery differed between cases and controls; with preeclampsia, although very rare, being more common amongst cases born by caesarean (OR 8.91, 95% CI 1.48, 53.42).

CONCLUSIONS

Our obstetric record-based study found no significant evidence that caesarean delivery increased the risk of childhood ALL, either overall or when carried out before labour.

Increased risk of hemangioma after exposure to neonatal phototherapy in infants with predisposing risk factors

AIM

To determine the relationship between neonatal phototherapy and future risk of clinically significant hemangioma.

METHODS

We analysed a cohort of 678 879 infants born after 34 weeks gestation comprising 3 975 242 person-years of follow-up over 11 years (2006-2016). The exposure was phototherapy the first 28 days of life. The outcome was hemangioma that required in-hospital treatment during follow-up. We estimated hazard ratios (HR) and 95% confidence intervals (CI) for the association of phototherapy with risk of hemangioma, accounting for preterm birth, low birthweight and congenital anomalies.

RESULTS

The incidence of hemangioma was greater in neonates who received phototherapy than in untreated infants, but there was no association in adjusted models (HR 1.19, 95% CI 0.89-1.58). Risk of hemangioma was elevated in infants who received phototherapy and were born late preterm (HR 2.35, 95% CI 1.51-3.64), with low birthweight (HR 1.91, 95% CI 1.12-3.24), or with anomalies (HR 5.09, 95% CI 3.42-7.58). Without phototherapy, these three risk factors were more weakly associated with hemangioma.

CONCLUSION

Neonatal phototherapy in infants with predisposing risk factors may increase the chance of hemangioma, but confirmation in further studies is needed.

Birth Weight and Risk of Childhood Acute Lymphoblastic Leukemia in Arizona, Illinois, and Kentucky

OBJECTIVE

To confirm the previously reported increased risk of leukemia among macrosomic children (those with birth weight >4 kg).

METHODS

Birth certificates of Arizona, Illinois, and Kentucky children diagnosed as having acute lymphoblastic leukemia (ALL) before age 5 years were matched with birth certificates from leukemia-free children of the same sex, race, and ethnicity who were born in the same county on or about the same day. Odds ratios (ORs) for ALL among children of low (<2.5 kg) or high (>4 kg) birth weight were calculated by conditional logistic regression.

RESULTS

Children with high birth weight had an elevated risk of ALL in the first 5 years of life (OR 1.28, 95% confidence interval [CI] 1.01-1.61). The excess risk was confined to non-Hispanic whites (OR 1.77, 95% CI 1.27-2.48), both boys (OR 1.57, 95% CI 1.01-2.45) and girls (OR 2.10, 95% CI 1.26-3.52).

CONCLUSIONS

This study confirms the association between high birth weight and ALL previously reported by other studies in children of European ancestry. The literature on maternal risk factors for both macrosomia and ALL is reviewed, with maternal overnutrition emerging as a plausible risk factor for both outcomes.

Cancer risk in children and young adults born preterm: A systematic review and meta-analysis

Introduction

Risk of developing a malignancy when born premature is unknown. We hypothesised that risk of certain cancers might be increased in youth born preterm versus term. We therefore performed a systematic review and meta-analysis to evaluate the incidence of malignancy in the context of preterm birth, according to various cancer types.

Methods

The study was designed per MOOSE and PRISMA guidelines. Articles were identified through November 2015. Observational studies exploring the association between childhood malignancy and birth characteristics were included. Of the 1658 records identified, 109 full text articles were evaluated for eligibility. Random effects meta-analyses were conducted on 10/26 studies retained; 95% confidence intervals were computed and adjusted following sensitivity analysis. Publication bias was evaluated using funnel plots, Begg’s and Egger’s tests.

Results

No differences in risk of primary central nervous system tumor [OR 1.05; 95% CI 0.93–1.17, 5 studies, 580 cases] and neuroblastoma [OR 1.09; 95% CI 0.90–1.32, 5 studies, 211 cases] were observed in individuals born <37 versus ≥37 weeks’ gestation. Preterm birth was consistently associated with hepatoblastoma [ORs 3.12 (95% CI 2.32–4.20), 1.52 (95% CI 1.1–2.1), 1.82 (95% CI 1.01–3.26), and 2.65 (95% CI 1.98–3.55)], but not leukemia, astrocytoma, ependymoma, medulloblastoma, lymphoma, nephroblastoma, rhabdomyosarcoma, retinoblastoma or thyroid cancer.

Conclusions

Children born premature may be at increased risk for hepatoblastoma but there is no strong evidence of an increased risk of primary central nervous system tumours or neuroblastoma. There is insufficient evidence to conclude whether prematurity modulates the risk of other childhood cancers.

Frequency and duration of phototherapy in preterm infants <35 weeks gestation

OBJECTIVE

To evaluate the frequency, age at phototherapy (PT) initiation, and duration of PT use in infants 23^0/7 to 34^6/7 weeks of gestation in two neonatal intensive care units (NICUs) over 4 time periods.

STUDY DESIGN

We reviewed the charts of all infants born at 23^0/7-34^6/7 weeks of gestational age (GA) and admitted to the NICUs of two hospitals between January 2009 and September 2015. We calculated the proportion of infants who received PT and the total duration of PT exposure.

RESULTS

Overall 2023 (81.8%) received PT, and PT use was inversely related to GA and birthweight. More infants received PT when GA was added as a criterion for initiating PT. The median duration (interquartile range (IQR)) of PT for all infants was 50 (27-85) h and in the lowest GA group was 74 (42-111) h.

CONCLUSIONS

Recent US consensus guidelines appear to have led to an increased use of PT in our NICUs and studies from Norway indicate that we use PT considerably more frequently and for longer durations than do our Norwegian colleagues.

Cesarean Delivery and Childhood Malignancies: A Single-Center, Population-Based Cohort Study

Rising rates of cesarean deliveries worldwide prompt the evaluation of long-term morbidity to the offspring. In this retrospective cohort study, we evaluated whether cesarean delivery influences the development of childhood malignancies. We identified an association of cesarean delivery with acute lymphoblastic leukemia in children, suggesting prudence in the recommendation of cesarean delivery for nonmedically indicated cases.

Failed Vacuum and the Long-term Hematologic Morbidity of the Offspring

OBJECTIVE

We aimed to investigate the effect of failed vacuum delivery leading to an emergency cesarean delivery on the long-term pediatric hematologic morbidity of the offspring.

STUDY DESIGN

In this population-based cohort study, the risk of long-term hematologic morbidity (up to the age of 18 y) was evaluated in children born following successful vacuum vaginal delivery, as compared with that of children born following a failed procedure leading to an emergent cesarean delivery. Multiple pregnancies and fetuses with congenital malformations were excluded. A Kaplan-Meier survival curve was constructed to compare cumulative pediatric hematologic morbidity, and a Cox proportional hazards model was used to control for confounders.

RESULTS

A total of 7978 neonates met the inclusion criteria. Vacuum delivery was successful in 7733 cases (96.9%), whereas it failed in 245 cases (3.1%). Total hematologic morbidity of the offspring up to 18 years of age was comparable between the groups (1.6% vs. 0.8%, P=0.8). The Kaplan-Meier survival curve showed no difference in the cumulative incidence of total hematologic morbidity (log rank, P=0.22). In the Cox regression model, failed vacuum delivery was not independently associated with long-term hematologic morbidity, as compared with a successful procedure, while adjusting for multiple confounders (adjusted hazards ratio [HR], 1.8; 95% confidence interval, 0.7-5.0; P=0.25).

CONCLUSIONS

Failed vacuum delivery does not seem to be associated with an increased risk for pediatric hematologic morbidity of the offspring up to 18 years of age.

Gestational age and childhood leukemia: A meta-analysis of epidemiologic studies

OBJECTIVE

An increasing amount of evidence shows that childhood leukemia is initiated in utero. Birth characteristics initiated in utero, such as gestational age, may play a role in leukemogenesis. The purpose of our meta-analysis is to explore the association between gestational age and childhood leukemia.

METHODS

Relevant studies up to 21 April 2017 were collected by searching PubMed and EMBASE databases. Subgroup analysis, sensitivity analysis and publication bias assessment were conducted.

RESULTS

A total of 13 studies were included. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) for preterm birth and postterm birth were 1.06 (0.98, 1.13) and 1.01 (0.90, 1.13) for childhood leukemia, 1.04 (0.97, 1.11) and 1.03 (0.95, 1.12) for acute lymphocytic leukemia (ALL), 1.20 (1.00, 1.44) and 1.20 (1.00, 1.43) for acute myeloid leukemia (AML), compared with full-term birth. Study type and study region were the reasons behind the heterogeneity. In subgroup analyses, the summary ORs with 95% CI for childhood leukemia and ALL were 1.23 (1.07, 1.41) and 1.21 (1.06, 1.39) for postterm birth in cohort studies. No significant changes in sensitivity analyses and no publication bias were observed in our analysis.

CONCLUSION

Our results suggest that both preterm and postterm infants have an elevated risk of developing AML. In addition, postterm birth increased the risk of childhood leukemia and ALL in cohort studies. However, more studies are warranted to validate these results and explore the biologic mechanisms underlying these relationships.

Mother and child characteristics at birth and early age leukemia: a case-cohort population-based study

OBJECTIVE

The population-based cancer registries (PBCR) and the Information System on Live Births in Brazil (Sistema de Informações sobre Nascidos Vivos [SINASC]) have information that enables the test for risk factors associated with leukemia at an early age. The aim of this study was to identify maternal and birth characteristics associated with early-age acute leukemia (EAL) in Brazil.

METHODS

A case-cohort study was performed using secondary dataset information of PBCR and SINASC. The risk association variables were grouped into (i) characteristics of the child at birth and (ii) characteristics of maternal exposure during pregnancy. The case-control ratio was 1:4. Linkage was performed using R software; odds ratio (OR) and 95% confidence interval (CI) were calculated by logistic regression models.

RESULTS

EAL was associated with maternal occupational exposure to chemicals (agricultural, chemical, and petrochemical industry; adjOR: 2.18, 95% CI: 1.16-4.10) and with birth defects (adjOR: 3.62, 95% CI: 1.19-11.00).

CONCLUSIONS

The results of this study, with the identification of EAL risk factors in population-based case-cohort study, strengthen the knowledge and improve databases, contributing to investigations on risk factors associated with childhood leukemia worldwide.

Maternal diabetes and risk of childhood acute lymphoblastic leukaemia in the offspring

BACKGROUND

Maternal diabetes may be linked to childhood acute lymphoblastic leukaemia (ALL) in the offspring.

METHODS

We assessed the association between maternal pregestational or gestational diabetes and offspring risk of childhood ALL in a register-based study, including all singletons born in Denmark during 1996-2015 (n=1 187 482).

RESULTS

Adjusted hazard ratios of childhood ALL were 2.91 (95% confidence interval (CI): 1.30-6.51) for maternal pregestational diabetes and 1.75 (95% CI: 1.02-2.98) for maternal gestational diabetes. Paternal diabetes did not alter offspring ALL risk, and we found no association between offspring ALL and later maternal risk of diabetes.

CONCLUSIONS

Regardless that absolute ALL risk among offspring of women with diabetes remains low, our findings suggest that characteristics of the diabetic intrauterine environment promote ALL development. This offers a setting for future research into the biological mechanisms underlying childhood ALL.

Pediatric cancer risk in association with birth defects: A systematic review

BACKGROUND

Many epidemiological studies have examined associations between birth defects (BDs) and pediatric malignancy over the past several decades. Our objective was to conduct a systematic literature review of studies reporting on this association.

METHODS

We used librarian-designed searches of the PubMed Medline and Embase databases to identify primary research articles on pediatric neoplasms and BDs. English language articles from PubMed and Embase up to 10/12/2015, and in PubMed up to 5/12/2017 following an updated search, were eligible for inclusion if they reported primary epidemiological research results on associations between BDs and pediatric malignancies. Two reviewers coded each article based on the title and abstract to identify eligible articles that were abstracted using a structured form. Additional articles were identified through reference lists and other sources. Results were synthesized for pediatric cancers overall and for nine major pediatric cancer subtypes.

RESULTS

A total of 14,778 article citations were identified, of which 80 met inclusion criteria. Pediatric cancer risk was increased in most studies in association with BDs overall with some notable specific findings, including increased risks for CNS tumors in association with CNS abnormalities and positive associations between rib anomalies and several pediatric cancer types.

CONCLUSIONS

Some children born with BDs may be at increased risk for specific pediatric malignancy types. This work provides a foundation for future investigations that are needed to clarify specific BD types predisposing toward malignancy and possible underlying causes of both BDs and malignancy.

Maternal Smoking and the Risk of Cancer in Early Life - A Meta-Analysis

BACKGROUND

In spite of the well-known harmful effects on the fetus, many women continue smoking during pregnancy. Smoking as an important source of toxic chemicals may contribute to the developmental origin of diseases.

OBJECTIVES

The aim of this work was to pursue the possible association between maternal smoking and cancer in early life. Specifically, we wanted to identify the associated early life cancer types, and to quantify the associations.

METHODS

In a systematic literature search 825 articles were identified in PubMed and Web of Science, and 55 more through the reference lists. Of these 62 fulfilled the criteria for inclusion in meta-analyses. Using Mantel-Haenszel or DerSimonian and Laird method, depending on heterogeneity of the studies, pooled estimates and 95% confidence intervals for eight cancer types were calculated.

RESULTS

Smoking during pregnancy was associated with an increased risk for for brain and central nervous system tumors (OR = 1.09; 95% CI = 1.02-1.17). Although the risk for lymphoma was also associated (OR = 1.21; 95% CI = 1.05-1.34), it did not hold up in subgroup analyses. Leukemia was not found to be associated with maternal smoking. Five other cancer types (bone, soft tissue, renal, hepatic, and germ cell cancer) were also examined, but the number of studies was too limited to exclude the possibility of maternal smoking as a risk factor for cancer in offspring.

CONCLUSIONS

According to our meta-analyses, maternal smoking is associated with nervous system cancers, but not with leukemia in early life. Confirming or rejecting associations of maternal smoking with lymphoma and the five other cancer types requires further studies.

Maternal pre-pregnancy and gestational diabetes, obesity, gestational weight gain, and risk of cancer in young children: a population-based study in California

PURPOSE

We aimed to examine the influence of pre-pregnancy diabetes, pre-pregnancy body mass index (BMI), gestational diabetes, and gestational weight gain on childhood cancer risk in offspring.

METHODS

We identified cancer cases (n = 11,149) younger than age 6 years at diagnosis from the California Cancer Registry registered between 1988 and 2013. Controls (n = 270,147) were randomly sampled from California birth records, and frequency matched by year of birth to all childhood cancers during the study period. Exposure and covariate information were extracted from birth records. Unconditional logistic regression models were generated to assess the importance of pre-pregnancy diabetes, pre-pregnancy BMI, gestational diabetes, and gestational weight gain on childhood cancer risk.

RESULTS

We observed increased risks of acute lymphoblastic leukemia and Wilms' tumor in children of mothers with pre-pregnancy diabetes [odds ratio (OR) 95 % confidence interval (CI) 1.37 (1.11, 1.69); OR (95 % CI) 1.45 (0.97, 2.18), respectively]. When born to mothers who were overweight prior to pregnancy (BMI 25-<30), children were at increased risk of leukemia [OR (95 % CI) 1.27 (1.01, 1.59)]. Insufficient gestational weight gain increased the risk of acute myeloid leukemia [OR (95 % CI) 1.50 (0.92, 2.42)] while excessive gestational weight gain increased the risk of astrocytomas [OR (95 % CI) 1.56 (0.97, 2.50)]. No associations were found between gestational diabetes and childhood cancer risk in offspring.

CONCLUSIONS

We estimated elevated risks of several childhood cancers in the offspring of mothers who had diabetes and were overweight prior to pregnancy, as well as mothers who gained insufficient or excessive weight. Since few studies have focused on these factors in relation to childhood cancer, replication of our findings in future studies is warranted.

Environmental, maternal, and reproductive risk factors for childhood acute lymphoblastic leukemia in Egypt: a case-control study

BACKGROUND

Acute lymphocytic leukemia (ALL) is the most common pediatric cancer. The exact cause is not known in most cases, but past epidemiological research has suggested a number of potential risk factors. This study evaluated associations between environmental and parental factors and the risk for ALL in Egyptian children to gain insight into risk factors in this developing country.

METHODS

We conducted a case-control design from May 2009 to February 2012. Cases were recruited from Children's Cancer Hospital, Egypt (CCHE). Healthy controls were randomly selected from the general population to frequency-match the cumulative group of cases by sex, age groups (<1; 1 - 5; >5 - 10; >10 years) and region of residence (Cairo metropolitan region, Nile Delta region (North), and Upper Egypt (South)). Mothers provided answers to an administered questionnaire about their environmental exposures and health history including those of the father. Odds ratios (ORs) and 95 % confidence intervals (CI) were calculated using logistic regression with adjustment for covariates.

RESULTS

Two hundred ninety nine ALL cases and 351 population-based controls frequency-matched for age group, gender and location were recruited. The risk of ALL was increased with the mother's use of medications for ovulation induction (ORadj = 2.5, 95 % CI =1.2 -5.1) and to a lesser extend with her age (ORadj = 1.8, 95 % CI = 1.1 - 2.8, for mothers ≥ 30 years old). Delivering the child by Cesarean section, was also associated with increased risk (ORadj = 2.01, 95 % CI =1.24-2.81).

CONCLUSIONS

In Egypt, the risk for childhood ALL appears to be associated with older maternal age, and certain maternal reproductive factors.

Parental Tobacco Smoking and Acute Myeloid Leukemia: The Childhood Leukemia International Consortium

The association between tobacco smoke and acute myeloid leukemia (AML) is well established in adults but not in children. Individual-level data on parental cigarette smoking were obtained from 12 case-control studies from the Childhood Leukemia International Consortium (CLIC, 1974-2012), including 1,330 AML cases diagnosed at age <15 years and 13,169 controls. We conducted pooled analyses of CLIC studies, as well as meta-analyses of CLIC and non-CLIC studies. Overall, maternal smoking before, during, or after pregnancy was not associated with childhood AML; there was a suggestion, however, that smoking during pregnancy was associated with an increased risk in Hispanics (odds ratio = 2.08, 95% confidence interval (CI): 1.20, 3.61) but not in other ethnic groups. By contrast, the odds ratios for paternal lifetime smoking were 1.34 (95% CI: 1.11, 1.62) and 1.18 (95% CI: 0.92, 1.51) in pooled and meta-analyses, respectively. Overall, increased risks from 1.2- to 1.3-fold were observed for pre- and postnatal smoking (P < 0.05), with higher risks reported for heavy smokers. Associations with paternal smoking varied by histological type. Our analyses suggest an association between paternal smoking and childhood AML. The association with maternal smoking appears limited to Hispanic children, raising questions about ethnic differences in tobacco-related exposures and biological mechanisms, as well as study-specific biases.

Smoking in pregnancy and risk of cancer among young children: A population-based study

Smoking during pregnancy is a plausible risk factor for childhood cancer, yet previous studies have yielded conflicting results, and few prospective studies have been published. Data on maternal smoking were obtained from California birth certificates. We linked California birth certificates (births 2007-2011) with California Cancer Registry records for childhood cancer cases (diagnosed January 2007-September 2013) that were ages 5 or younger at diagnosis (N cases = 2,021). Controls (N = 40,356) were frequency-matched by birth year and randomly selected from birth certificate records. We used unconditional logistic regression to obtain odds ratios (OR) and 95% confidence intervals (CI) to assess the association between smoking during pregnancy and childhood cancer. We observed positive associations for gliomas (OR = 1.8, 95% CI: 1.0-3.4) and retinoblastoma (OR = 3.0, 95% CI: 1.4-6.6), particularly bilateral retinoblastoma (OR = 9.4, 95% CI 3.6-24.7) with maternal smoking in pregnancy. Maternal smoking during pregnancy may be a risk factor for retinoblastoma and certain types of childhood brain tumors.

Neonatal Phototherapy and Infantile Cancer

OBJECTIVE

To determine whether neonatal phototherapy is associated with cancer in the first year after birth.

METHODS

We analyzed a data set from the California Office of Statewide Health Planning and Development that was created by linking birth certificates, death certificates, and hospital discharge abstracts up to age 1 year. Subjects were 5 144 849 infants born in California hospitals at ≥35 weeks' gestation from 1998 to 2007. We used International Classification of Diseases, Ninth Revision codes to identify phototherapy at <15 days and discharge diagnoses of cancer at 61 to 365 days. We adjusted for potential confounding variables by using traditional and propensity-adjusted logistic regression models.

RESULTS

Cancer was diagnosed in 58/178 017 infants with diagnosis codes for phototherapy and 1042/4 966 832 infants without such codes (32.6/100 000 vs 21.0/100 000; relative risk 1.6; 95% confidence interval [CI], 1.2-2.0, P = .002). In propensity-adjusted analyses, associations were seen between phototherapy and overall cancer (adjusted odds ratio [aOR] 1.4; 95% CI, 1.1-1.9), myeloid leukemia (aOR 2.6; 95% CI, 1.3-5.0), and kidney cancer (aOR 2.5; 95% CI, 1.2-5.1). The marginal propensity-adjusted absolute risk increase for cancer after phototherapy in the total population was 9.4/100 000 (number needed to harm of 10 638). Because of the higher baseline risk of cancer in infants with Down syndrome, the number needed to harm was 1285.

CONCLUSIONS

Phototherapy may slightly increase the risk of cancer in infancy, although the absolute risk increase is small. This risk should be considered when making phototherapy treatment decisions, especially for infants with bilirubin levels below current treatment guidelines.

Retrospective Cohort Study of Phototherapy and Childhood Cancer in Northern California

OBJECTIVE

To investigate the association between neonatal phototherapy use and childhood cancer.

METHODS

This retrospective cohort study included 499 621 children born at ≥35 weeks' gestation from 1995 to 2011 in Kaiser Permanente Northern California hospitals, who survived to hospital discharge and were followed ≥60 days. We obtained data on home and inpatient phototherapy, covariates, and cancer incidence from electronic records. We used propensity-adjusted Cox and Poisson models to control for confounding and unequal follow-up times.

RESULTS

There were 60 children with a diagnosis of cancer among 39 403 exposed to phototherapy (25 per 100 000 person-years), compared with 651 of 460 218 unexposed children (18 per 100 000 person-years; incidence rate ratio [IRR] 1.4; P = .01). Phototherapy was associated with increased rates of any leukemia (IRR 2.1; P = .0007), nonlymphocytic leukemia (IRR 4.0; P = .0004), and liver cancer (IRR 5.2; P = .04). With adjustment for a propensity score that incorporated bilirubin levels, chromosomal disorders, congenital anomalies, and other covariates, associations were no longer statistically significant: Adjusted hazard ratios (95% confidence intervals) were 1.0 (0.7-1.6) for any cancer, 1.6 (0.8-3.5) for any leukemia, 1.9 (0.6-6.9) for nonlymphocytic leukemia, and 1.4 (0.2-12) for liver cancer. Upper limits of 95% confidence intervals for adjusted 10-year excess risk were generally <0.1% but reached 4.4% for children with Down syndrome.

CONCLUSIONS

Although phototherapy use was associated with increased cancer rates (particularly nonlymphocytic leukemia), control for confounding variables eliminated or attenuated the associations. Nonetheless, the possibility of even partial causality suggests that avoiding unnecessary phototherapy may be prudent.

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.

History of Maternal Fetal Loss and Childhood Leukaemia Risk in Subsequent Offspring: Differentials by Miscarriage or Stillbirth History and Disease Subtype

BACKGROUND

Despite the putative intrauterine origins of childhood (0-14 years) leukaemia, it is complex to assess the impact of perinatal factors on disease onset. Results on the association of maternal history of fetal loss (miscarriage/stillbirth) with specific disease subtypes in the subsequent offspring are in conflict. We sought to investigate whether miscarriage and stillbirth may have different impacts on the risk of acute lymphoblastic leukaemia (ALL) and of its main immunophenotypes (B-cell and T-cell ALL), as contrasted to acute myeloid leukaemia (AML).

METHODS

One thousand ninety-nine ALL incidents (957 B-ALL) and 131 AML cases along with 1:1 age and gender-matched controls derived from the Nationwide Registry for Childhood Hematological Malignancies and Brain Tumors (1996-2013) were studied. Multivariable regression models were used to assess the roles of previous miscarriage(s) and stillbirth(s) on ALL (overall, B-, T-ALL) and AML, controlling for potential confounders.

RESULTS

Statistically significant exposure and disease subtype-specific associations of previous miscarriage(s) exclusively with AML [odds ratio (OR) 1.67, 95% confidence interval (CI) 1.00, 2.81] and stillbirth(s) with ALL [OR 4.82, 95% CI 1.63, 14.24] and B-ALL particularly, emerged.

CONCLUSION

Differential pathophysiological pathways pertaining to genetic polymorphisms or cytogenetic aberrations are likely to create hostile environments leading either to fetal loss or the development of specific leukaemia subtypes in subsequent offspring, notably distinct associations of maternal miscarriage history confined to AML and stillbirth history confined to ALL (specifically B-ALL). If confirmed and further supported by studies revealing underlying mechanisms, these results may shed light on the divergent leukemogenesis processes.

Birth Characteristics and Childhood Leukemia Risk: Correlations With Genetic Markers

Birth characteristics such as birth order, birth weight, birth defects, and Down syndrome showed some of the first risk associations with childhood leukemia. Examinations of correlations between birth characteristics and leukemia risk markers have been limited to birth weight-related genetic polymorphisms. We integrated information on nongenetic and genetic markers by evaluating the relationship of birth characteristics, genetic markers for childhood acute lymphoblastic leukemia (ALL) susceptibility, and ALL risk together. The multiethnic study consisted of cases with childhood ALL (n=161) and healthy controls (n=261). Birth characteristic data were collected through questionnaires, and genotyping was achieved by TaqMan SNP Genotyping Assays. We observed risk associations for birth weight over 4000 g (odds ratios [OR]=1.93; 95% confidence interval [CI], 1.16-3.19), birth length (OR=1.18 per inch; 95% CI, 1.01-1.38), and with gestational age (OR=1.10 per week; 95% CI, 1.00-1.21). Only the HFE tag single-nucleotide polymorphism (SNP) rs9366637 showed an inverse correlation with a birth characteristic, gestational age, with a gene-dosage effect (P=0.005), and in interaction with a transferrin receptor rs3817672 genotype (Pinteraction=0.05). This correlation translated into a strong association for rs9366637 with preterm birth (OR=5.0; 95% CI, 1.19-20.9). Our study provides evidence for the involvement of prenatal events in the development of childhood ALL. The inverse correlation of rs9366637 with gestational age has implications on the design of HFE association studies in birth weight and childhood conditions using full-term newborns as controls.

Race/ethnicity and the risk of childhood leukaemia: a case-control study in California

BACKGROUND

We conducted a large registry-based study in California to investigate the association between race/ethnicity and childhood leukaemia focusing on two subtypes: acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML).

METHODS

We obtained information on 5788 cases and 5788 controls by linking California cancer and birth registries. We evaluated relative risk of childhood leukaemia by race and ethnicity of the child and their parents using conditional logistic regression, with adjustment for potential confounders.

RESULTS

Compared with Whites, Black children had lower risk of ALL (OR=0.54, 95% CI 0.45 to 0.66) as well as children of Black/Asian parents (OR=0.31, 95% CI 0.10 to 0.94). Asian race was associated with increased risk of AML with OR=1.643, 95% CI 1.10 to 2.46 for Asian vs Whites; and OR=1.67, 95% CI 1.04 to 2.70 for Asian/Asian vs White/White. Hispanic ethnicity was associated with increased risk of ALL (OR=1.37, 95% CI 1.22 to 1.52). A gradient in risk of ALL was observed while comparing Hispanic children with both parents Hispanic, one parent Hispanic and non-Hispanic children (p Value for trend <0.0001). The highest risk of ALL was observed for children with a combination of Hispanic ethnicity and White race compared with non-Hispanic whites (OR=1.27, 95% CI 1.12 to 1.44). The lowest risk was observed for non-Hispanic blacks (OR=0.46, 95% CI 0.36 to 0.60). Associations for total childhood leukaemia were similar to ALL.

CONCLUSIONS

Our results confirm that there are ethnic and racial differences in the incidence of childhood leukaemia. These differences indicate that some genetic and/or environmental/cultural factors are involved in aetiology of childhood leukaemia.

Childhood acute lymphoblastic leukaemia and indicators of early immune stimulation: the Estelle study (SFCE)

Background:

Factors related to early stimulation of the immune system (breastfeeding, proxies for exposure to infectious agents, normal delivery, and exposure to animals in early life) have been suggested to decrease the risk of childhood acute lymphoblastic leukaemia (ALL).

Methods:

The national registry-based case–control study, ESTELLE, was carried out in France in 2010–2011. Population controls were frequency matched with cases on age and gender. The participation rates were 93% for cases and 86% for controls. Data were obtained from structured telephone questionnaires administered to mothers. Odds ratios (OR) were estimated using unconditional regression models adjusted for age, gender, and potential confounders.

Results:

In all, 617 ALL and 1225 controls aged ⩾1 year were included. Inverse associations between ALL and early common infections (OR=0.8, 95% confidence interval (CI): 0.6, 1.0), non-first born (⩾3 vs 1; OR=0.7, 95% CI: 0.5, 1.0), attendance of a day-care centre before age 1 year (OR=0.7, 95% CI: 0.5, 1.0), breastfeeding (OR=0.8, 95% CI: 0.7, 1.0), and regular contact with pets (OR=0.8, 95% CI: 0.7, 1.0) in infancy were observed.

Conclusions:

The results support the hypothesis that conditions promoting the maturation of the immune system in infancy have a protective role with respect to ALL.

Overdiagnosis: how our compulsion for diagnosis may be harming children

Overdiagnosis occurs when a true abnormality is discovered, but detection of that abnormality does not benefit the patient. It should be distinguished from misdiagnosis, in which the diagnosis is inaccurate, and it is not synonymous with overtreatment or overuse, in which excess medication or procedures are provided to patients for both correct and incorrect diagnoses. Overdiagnosis for adult conditions has gained a great deal of recognition over the last few years, led by realizations that certain screening initiatives, such as those for breast and prostate cancer, may be harming the very people they were designed to protect. In the fall of 2014, the second international Preventing Overdiagnosis Conference will be held, and the British Medical Journal will produce an overdiagnosis-themed journal issue. However, overdiagnosis in children has been less well described. This special article seeks to raise awareness of the possibility of overdiagnosis in pediatrics, suggesting that overdiagnosis may affect commonly diagnosed conditions such as attention-deficit/hyperactivity disorder, bacteremia, food allergy, hyperbilirubinemia, obstructive sleep apnea, and urinary tract infection. Through these and other examples, we discuss why overdiagnosis occurs and how it may be harming children. Additionally, we consider research and education strategies, with the goal to better elucidate pediatric overdiagnosis and mitigate its influence.

Cancer in children and young adults born after assisted reproductive technology: a Nordic cohort study from the Committee of Nordic ART and Safety (CoNARTaS)

STUDY QUESTION

Do children and young adults born after assisted reproductive technology (ART) have an increased risk of cancer?

SUMMARY ANSWER

Children born after ART showed no overall increase in the rate of cancer when compared with children born as a result of spontaneous conception.

WHAT IS KNOWN ALREADY

Children born after ART have more adverse perinatal outcomes, i.e. preterm births, low birthweights and birth defects. Previous studies have shown divergent results regarding the risk of cancer among children born after ART.

STUDY DESIGN, SIZE, DURATION

A retrospective Nordic population-based cohort study was performed, comprising all children born after ART in Sweden, Denmark, Finland and Norway between 1982 and 2007. The mean (±standard deviation) follow-up time was 9.5 (4.8) years.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Children born after ART (n = 91 796) were compared with a control group of children born after spontaneous conception. This control group was almost 4-fold the size of the ART group (n = 358 419) and matched for parity, year of birth and country. Data on perinatal outcomes and cancer were obtained from the National Medical Birth Registries, the Cancer Registries, the Patient Registries and the Cause of Death Registries. The cancer diagnoses were divided into 12 main groups. Hazard ratios (HRs) and adjusted HR were calculated. Adjustments were carried out for country, maternal age, parity, sex, gestational age and birth defects.

MAIN RESULTS AND THE ROLE OF CHANCE

There was no significant increase in overall cancer rates among children born after ART when compared with children born after spontaneous conception (adjusted HR 1.08; 95% CI 0.91-1.27). Cancer, of any form, was found among 181 children born after ART (2.0/1000 children, 21.0/100 000 person-years) compared with 638 children born after spontaneous conception (1.8/1000 children, 18.8/100 000 person-years). Leukaemia was the most common type of cancer (n = 278, 0.62/1000 children) but no significantly increased incidence was found among children born after ART. An increased risk was observed for 2 of 12 cancer groups. They were central nervous system tumours (adjusted HR 1.44; 95% CI 1.01-2.05) and malignant epithelial neoplasms (adjusted HR 2.03; 95% CI 1.06-3.89); the absolute risks were 0.46/1000 and 0.15/1000 children, respectively, corresponding to an absolute increased risk of 0.14/1000 and 0.08/1000 children, respectively.

LIMITATIONS, REASONS FOR CAUTION

As this is an observational study, the main limitation is the fact that it is not possible to adjust for all potential confounders. We were not able to control for confounders such as socio-economic status and perinatal factors, such as Apgar score, which other studies have suggested affect cancer rates.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this large population-based cohort study are in agreement with most previously published studies. The main findings are reassuring for couples undergoing ART, children born after ART and clinicians working with ART.

STUDY FUNDING/COMPETING INTERESTS

No conflict of interest was reported. The study was supported by grants from The European Society for Human Reproduction and Embryology (ESHRE), Sahlgrenska University Hospital, Gothenburg, Sweden, the University of Copenhagen, Denmark, the Danish Agency of Science, Technology and Innovation and the Nordic Federation of Societies of Obstetrics and Gynecology (NFOG).

Maternal and perinatal risk factors for childhood cancer: record linkage study

OBJECTIVE

To investigate maternal and perinatal risk factors for childhood cancer.

STUDY DESIGN

Case-control analysis of linked records from the Aberdeen Maternity and Neonatal Databank with the Scottish Cancer Registry and the General Registry of Births and Deaths in Scotland was carried out.

SETTING

Aberdeen, Scotland.

PARTICIPANTS

Cases (n=176) comprised children diagnosed with cancer under 15 years or recorded as having died of cancer. Four controls per case were matched by age and gender.

RISK FACTORS TESTED

Maternal age, body mass index, social class, marital status and smoking as well as pre-eclampsia, antepartum haemorrhage and previous miscarriage, gestational age, birth weight and Apgar scores were compared between groups to test for association with cancer. ORs with 95% CIs were calculated using conditional logistic regression in univariable and multivariable models.

RESULTS

Of the maternal characteristics tested, mother's age at delivery (cases mean 28.9 (SD 5.6) years vs controls mean 30.2 (SD 4.6), p=0.002) and smoking status (38.6% smokers among cases, 29.7% among controls, p=0.034) were found to be different between groups. Of the perinatal factors tested, low Apgar score at 5 min (adjusted OR (AOR) 4.59, 95% CI 1.52 to 13.87) and delivery by caesarean section (AOR 1.95, 95% CI 1.30 to 2.92) showed statistically significant associations with childhood cancer in the multivariable model.

CONCLUSIONS

Younger maternal age, maternal smoking, delivery by caesarean section and low Apgar score at 5 min were independently associated with increased risk of childhood cancer. These general findings should be interpreted with caution as this study did not have the power to detect any association with individual diagnostic categories of childhood cancer.