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

Lifecourse research in cancer: context, challenges, and opportunities when exploring exposures in early life and cancer risk in adulthood

As the global population ages, and rates of modifiable risk factors for cancer change, cancer incidence and mortality continue to increase. While we understand many modifiable risk factors related to diet, nutrition, bodyweight, and physical activity in adulthood that influence cancer risk, how exposure during childhood, adolescence, and young adulthood impacts cancer risk is less clear. This is partly because the timeline from initial mutation to cancer development and diagnosis can span several decades. This long latency period creates methodological, ethical, and financial issues; as well as resource and feasibility challenges in the design, implementation, and data analysis of lifecourse studies. As such, the large majority of lifecourse studies are observational, often using recall data which has inherent bias issues. Concurrently, a new research era has begun, with mature birth cohort studies that are phenotyped/genotyped and can support studies on adult cancer risk. Several studies and consortia contain information spanning the lifecourse. These resources can support association, mechanistic and epigenetic investigations into the influences of multi-disciplinary (e.g. genetic, behavioural, environmental) factors, across the lifecourse and critical time periods. Ultimately, we will be able to produce high-quality evidence and identify how/when early life risk factors impact cancer development and survival.

Association Between Perinatal Factors and Childhood Lymphoma-A Pooled Analysis of the ESCALE and ESTELLE Studies (SFCE)

CONTEXT

There is much interest in the perinatal period in relation to childhood cancer aetiology, with most studies focussing on childhood leukaemia. This work aimed to investigate the associations between pregnancy-related and perinatal factors and childhood lymphoma.

METHODS

We conducted a pooled analysis of two French nationwide population-based case-control studies. Data on sociodemographic, perinatal and lifestyle factors were collected through maternal interviews. Odds ratios (OR) and 95% confidence intervals (CIs) were computed using adjusted logistic regression models, separately for non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL). Specific analyses also investigated Burkitt NHL and nodular sclerosis HL, two most common histological types in children.

RESULTS

We included 305 NHL, 328 HL and 2415 controls in this study. No associations were observed with gestational age, foetal growth indicators, folic acid supplementation, factors related to maternal fertility and reproductive history, or maternal smoking during pregnancy. Maternal coffee consumption during pregnancy was associated with NHL (>2 cups/day, OR = 1.5 [95% CI: 1.1-2.1]), with a dose-response relationship; while maternal alcohol consumption was associated with Burkitt NHL (OR = 1.5 [1.1-2.2]). Paternal smoking during preconception/pregnancy was associated with NHL (OR = 1.4 [1.1-1.8]). Breastfeeding (ever/never) was not significantly associated with NHL and HL, but an inverse log-linear trend was observed with the duration of breastfeeding for NHL (p = 0.04).

CONCLUSION

Maternal coffee and alcohol consumptions during pregnancy and paternal smoking during preconception/pregnancy might increase the risk of childhood NHL. While warranting replication, these findings could help us better understand the aetiology of childhood lymphoma.

The association between maternal smoking during pregnancy and multimorbidity of non-communicable chronic diseases trajectory in offspring

OBJECTIVES

Although a few studies have found that maternal smoke during pregnancy (MSDP) is linked to a range of non-communicable chronic diseases (NCDs) in offspring, its association with the onset, progression, and prognosis of multimorbidity of NCDs (MNCDs) has never been studied.

STUDY DESIGN

Population-based prospective cohort study.

METHOD

A total of 318,122 adults aged 18-87 years who were free of heart disease, stroke, and diabetes at baseline were selected. MNCDs was defined as the coexistence of two or three NCDs, including CVDs (coronary heart disease and stroke), cancer (digest, breast, lung, and urination), diabetes (type 1 and type 2), and CLRD (COPD and asthma). Then we used multi-state model to analyse the impacts of MSDP on the progression of MNCDs in the offspring. Associations between MSDP and transition trajectory were analyzed with results expressed as hazard ratio (HR) and 95% confidence interval (95% CI).

RESULTS

During the 70.2 years of follow-up, a total of 112,894 participants developed first NCDs (FNCDs), among whom 28,195 developed MNCDs and 21,452 subsequently died. After adjustment for potential confounders, the MSDP was associated with the transition trajectory from baseline to FNCD (HR = 1.10, 95%CI:1.09-1.11) and from FNCDs to MNCDs (HR = 1.08,95%CI:1.06-1.10). Meanwhile, the MSDP was associated with the transition trajectory from MNCDs to death (HR = 1.07,95%CI:1.03-1.11). Further, these association became more pronounced among the offspring who smoke (HRbaseline→FNCDs=1.13, 95%CI:1.12-1.15; HRFNCD→MNCD=1.13, 95%CI:1.12-1.15; HRMNCDs→death=1.11, 95%CI:1.16-1.16); whereas among the offspring who do not smoke, only the transition trajectory from baseline to FNCDs was observed (HR = 1.07, 95%CI:1.05-1.09).

CONCLUSION

This study suggested that the MSDP is associated with almost all transition phases of MNCDs development and increases the mortality risk of MNCDs in offspring who smoke, and these transition trajectories can be largely reduced by smoking cessation among offspring.

Maternal smoking during pregnancy could accelerate aging in the adulthood: evidence from a perspective study in UK Biobank

BACKGROUND

Maternal smoking during pregnancy (MSDP) is significantly linked to the short- or long-term health of offspring. However, little research has examined whether MSDP affect the aging rate of offspring.

METHODS

This study used questionnaires to determine out whether the participants' mothers smoked when they were pregnant. For evaluating aging rate, we used the following several outcome measures: telomere length, frailty index, cognitive function, homeostatic dysregulation score, KDM-age, age-related hospitalization rate, premature death, and life expectancy.

RESULT

After adjusting for covariates, we found that the offspring of the MSDP group had significantly shorter telomere length in adulthood by 0.8 % (β = -0.008,95%CI:-0.009 to -0.006) compared with non-MSDP group. Compared to the non-MSDP group, participants in MSDP group showed higher levels of homeostatic dysregulation (β = 0.015,95%CI: 0.007-0.024) and were frailer (β = 0.008,95%CI:0.007-0.009). The KDM age increased by 0.100 due to MSDP (β = 0.100,95 % CI:0.018-0.181), and the age acceleration of KDM algorithm also increases significantly (β = 0.101, 95%CI:0.020-0.183). Additionally, we found that the risk of aging-related hospitalizations was significantly higher than the non-MSDP group by 10.4 %(HR = 1.104,95%CI:1.066-1.144). Moreover, MSDP group had a 12.2 % increased risk of all-cause premature mortality (HR = 1.122,95%CI:1.064-1.182) and a significant risk of lung cancer-specific premature mortality increased by 55.4 %(HR = 1.554,95%CI:1.346-1.793). In addition, participants in the MSDP group had significantly decreased cognitive function and shorter life expectancies than those in non-MSDP group.

CONCLUSION

Our findings indicated a significant association between MSPD and accelerated aging, elevated hospitalization rates, increased premature mortality rates, and reduced life expectancies in offspring.

[Smoking cessation during pregnancy]

Smoking during pregnancy is associated with negative pregnancy and perinatal health outcomes. Physiological and societal particularities can modify the smoking behavior of pregnant women. Pregnancy is a teachable moment for smoking cessation. Increased nicotine clearance may lead to exacerbated tobacco withdrawal symptoms and desire to smoke, which need to be taken into account when helping pregnant smokers to quit. Although most pregnant smokers try to quit on their own, 12% of pregnant women in France reported smoking in 2021 during the 3rd trimester of pregnancy. Health care professionals should screen for tobacco consumption and assess the level of addiction. Management of smoking cessation can be multidisciplinary, including non-pharmacological support such as counselling, behavioral support, financial reward contingent on abstinence, and medication (nicotine replacement therapies). Assessment and limitation of secondhand smoke exposure (SHS) is needed because SHS can also have negative maternal and fetal consequences. Management of relapse during the postpartum period is also to be anticipated; in 2021, it concerned 22.4% of women who had stopped smoking during pregnancy. While electronic cigarette use is increasing overall and among pregnant women who smoke (5.4 before pregnancy, 1.3% during the 3rd trimester in 2021), well-conducted smoking cessation studies are necessary to assess its benefits and potential risks in this specific group of smokers.

Prenatal exposure to maternal smoking and adult lung cancer risk: a nested case-control study using peripheral blood leukocyte DNA methylation prediction of exposure

A prior study reported no association between prenatal smoking methylation scores and adult lung cancer risk adjusting for methylation-predicted adult smoking, without considering maternal smoking trends by birth cohort. To address this gap, we examined the association between prenatal smoking methylation scores and adult lung cancer, independent of methylation-predicted adult packyears and by birth cohort, in a study nested in CLUE II. Included were 208 incident lung cancer cases ascertained by cancer registry linkage and 208 controls matched on age, sex, and smoking. DNA methylation was measured in prediagnostic blood. We calculated two prenatal smoking scores, using 19 (Score-19) and 15 (Score-15) previously identified CpGs and a methylation-predicted adult packyears score. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) adjusting for adult packyears score and batch effects. Score-15 was positively associated with lung cancer (per standard deviation, OR = 1.40, 95% CI = 1.10-1.79, P-trend = .006), especially in the 1930-1938 birth cohort (OR = 3.43, 95% CI = 1.55-7.60, P-trend = .002). Score-19 was associated only in the 1930-1938 birth cohort (OR = 2.12, 95% CI = 1.15-3.91). Participants with both prenatal scores below the median (vs all other combinations) had lower risk (OR = 0.44, 95% CI = 0.27-0.72), especially in the 1930-1938 birth cohort (OR = 0.16, 95% CI = 0.04-0.62). Among ever smokers, participants with higher prenatal smoking scores had higher risk, irrespective of adult packyears (low: OR = 2.81, 95% CI = 1.38-5.72, high: OR = 2.67, 95% CI = 1.03-6.95). This prospective study suggests a positive association between prenatal smoking exposure and adult lung cancer risk, especially in the 1930-1938 birth cohort, independent of active smoking. Future studies with multiple birth cohorts are needed.

Maternal Lifestyle and Prenatal Risk Factors for Childhood Leukemia: A Review of the Existing Evidence

BACKGROUND

Acute leukemia is the most common pediatric cancer, with an incidence peak at 2-5 years of age. Despite the medical advances improving survival rates, children suffer from significant side effects of treatments as well as its high social and economic impact. The frequent prenatal origin of this developmental disease follows the two-hit carcinogenesis model established in the 70s: a first hit in prenatal life with the creation of genetic fusion lesions or aneuploidy in hematopoietic progenitor/stem cells, and usually a second hit in the pediatric age that converts the preleukemic clone into clinical leukemia. Previous research has mostly focused on postnatal environmental factors triggering the second hit.

SUMMARY

There is scarce evidence on prenatal risk factors associated with the first hit. Mainly retrospective case-control studies suggested several environmental and lifestyle determinants as risk factors. If these associations could be confirmed, interventions focused on modifying prenatal factors might influence the subsequent risk of leukemia during childhood and reveal unexplored research avenues for the future. In this review, we aim to comprehensively summarize the currently available evidence on prenatal risk factors for the development of childhood leukemia. According to the findings of this review, parental age, ethnicity, maternal diet, folate intake, alcohol consumption, X-ray exposure, pesticides, perinatal infections, and fetal growth may have a significant role in the appearance of preleukemic lesions during fetal life. Other factors such as socioeconomic status, consumption of caffeinated beverages, and smoking consumption have been suggested with inconclusive evidence. Additionally, investigating the association between prenatal factors and genetic lesions associated with childhood leukemia at birth is crucial. Prospective studies evaluating the link between lifestyle factors and genetic alterations could provide indirect evidence supporting new research avenues for leukemia prevention. Maternal diet and lifestyle factors are modifiable determinants associated with adverse perinatal outcomes that could be also related to preleukemic lesions.

KEY MESSAGES

Parental age, ethnicity, maternal diet, folate intake, alcohol consumption, X-ray exposure, pesticides, perinatal infections, and fetal growth may have a significant role in the appearance of preleukemic lesions during fetal life. Dedicating efforts to studying maternal lifestyle during pregnancy and its association with genetic lesions leading to childhood leukemia could lead to novel prevention strategies.

Nicotine or marijuana vaping exposure during pregnancy and altered immune responses in offspring

Electronic nicotine delivery systems (ENDS) - which include electronic cigarettes or e-cigarettes, or simply e-cigs, and marijuana vaping have become increasingly popular. ENDS devices have been established as one of the tobacco quit methods and promoted to be safer compared to traditional tobacco cigarettes. Emerging evidence demonstrates that e-cigarette and marijuana vape use can be harmful, with potential associations with cancer. Herein, we summarize the level of evidence to date for altered immune response, with a focus on cancer risks in the offspring after maternal use of, or aerosol exposures from, ENDS or marijuana vape during pregnancy. From 27 published articles retrieved from PubMed, we sought to find out identified carcinogens in ENDS aerosols and marijuana vapor, which cross the placental barrier and can increase cancer risk in the offspring. Carcinogens in vaping aerosols include aldehydes, metals, tobacco-specific nitrosamines, tobacco alkaloids, polycyclic aromatic hydrocarbons, and volatile organic compounds. Additionally, there was only one passive vaping exposure case study on a human fetus, which noted that glycerol, aluminum, chromium, nickel, copper, zinc, selenium, and lead crossed from the mother to the offspring's cord blood. The carcinogens (metals) in that study were at lower concentrations compared to the mother's biological matrices. Lastly, we observed that in utero exposures to ENDS-associated chemicals can occur in vital organs such as the lungs, kidneys, brain, bladder, and heart. Any resulting DNA damage increases the risk of tumorigenesis. Future epidemiological studies are needed to examine the effects of passive aerosol exposures from existing and emerging electronic nicotine and marijuana products on developing offspring to cancer.

Maternal smoking, nutritional factors at different life stage, and the risk of incident type 2 diabetes: a prospective study of the UK Biobank

BACKGROUND

This study aims to investigate potential interactions between maternal smoking around birth (MSAB) and type 2 diabetes (T2D) pathway-specific genetic risks in relation to the development of T2D in offspring. Additionally, it seeks to determine whether and how nutritional factors during different life stages may modify the association between MSAB and risk of T2D.

METHODS

This study included 460,234 participants aged 40 to 69 years, who were initially free of T2D from the UK Biobank. MSAB and breastfeeding were collected by questionnaire. The Alternative health eating index(AHEI) and dietary inflammation index(DII) were calculated. The polygenic risk scores(PRS) of T2D and pathway-specific were established, including β-cell function, proinsulin, obesity, lipodystrophy, liver function and glycated haemoglobin(HbA1c). Cox proportion hazards models were performed to evaluate the gene/diet-MSAB interaction on T2D. The relative excess risk due to additive interaction (RERI) were calculated.

RESULTS

During a median follow-up period of 12.7 years, we identified 27,342 cases of incident T2D. After adjustment for potential confounders, participants exposed to MSAB had an increased risk of T2D (HR=1.11, 95%CI:1.08-1.14), and this association remained significant among the participants with breastfeeding (HR= HR=1.10, 95%CI: 1.06-1.14). Moreover, among the participants in the highest quartile of AHEI or in the lowest quartile of DII, the association between MSAB and the increased risk of T2D become non-significant (HR=0.94, 95%CI: 0.79-1.13 for AHEI; HR=1.09, 95%CI:0.99-1.20 for DII). Additionally, the association between MSAB and risk of T2D became non-significant among the participants with lower genetic risk of lipodystrophy (HR=1.06, 95%CI:0.99-1.14), and exposed to MSAB with a higher genetic risk for β-cell dysfunction or lipodystrophy additively elevated the risk of T2D(RERI=0.18, 95%CI:0.06-0.30 for β-cell function; RERI=0.16, 95%CI:0.04-0.28 for lipodystrophy).

CONCLUSIONS

This study indicates that maintaining a high dietary quality or lower dietary inflammation in diet may reduce the risk of T2D associated with MSAB, and the combination of higher genetic risk of β-cell dysfunction or lipodystrophy and MSAB significantly elevate the risk of T2D in offspring.

A life-course approach to tackling noncommunicable diseases in women

Women's health has been critically underserved by a failure to look beyond women's sexual and reproductive systems to adequately consider their broader health needs. In almost every country in the world, noncommunicable diseases are the leading causes of death for women. Among these, cardiovascular disease (including heart disease and stroke) and cancer are the major causes of mortality. Risks for these conditions exist at each stage of women's lives, but recognition of the unique needs of women for the prevention and management of noncommunicable diseases is relatively recent and still emerging. Once they are diagnosed, treatments for these diseases are often costly and noncurative. Therefore, we call for a strategic, innovative life-course approach to identifying disease triggers and instigating cost-effective measures to minimize exposure in a timely manner. Prohibitive barriers to implementing this holistic approach to women's health exist in both the social arena and the medical arena. Recognizing these impediments and implementing practical approaches to surmounting them is a rational approach to advancing health equity for women, with ultimate benefits for society as a whole.

The Exposome and Nutritional Pharmacology and Toxicology: A New Application for Metabolomics

The exposome refers to all of the internal and external life-long exposures that an individual experiences. These exposures, either acute or chronic, are associated with changes in metabolism that will positively or negatively influence the health and well-being of individuals. Nutrients and other dietary compounds modulate similar biochemical processes and have the potential in some cases to counteract the negative effects of exposures or enhance their beneficial effects. We present herein the concept of Nutritional Pharmacology/Toxicology which uses high-information metabolomics workflows to identify metabolic targets associated with exposures. Using this information, nutritional interventions can be designed toward those targets to mitigate adverse effects or enhance positive effects. We also discuss the potential for this approach in precision nutrition where nutrients/diet can be used to target gene-environment interactions and other subpopulation characteristics. Deriving these "nutrient cocktails" presents an opportunity to modify the effects of exposures for more beneficial outcomes in public health.

In Utero and Childhood/Adolescence Exposure to Tobacco Smoke, Genetic Risk, and Cancer Incidence in Adulthood: A Prospective Cohort Study

OBJECTIVE

To evaluate the association of early-life tobacco smoke exposure, especially interacting with cancer genetic variants, with adult cancer.

PARTICIPANTS AND METHODS

We examined the associations of in utero tobacco smoke exposure, age of smoking initiation, and their interaction with genetic risk levels with cancer incidence in 393,081 participants from the UK Biobank. Information on tobacco exposure was obtained by self-reported questionnaires. A cancer polygenic risk score was constructed by weighting and integrating 702 genome-wide association studies-identified risk variants. Cox proportional hazards regression models were used to calculate hazard ratios (HRs) for overall cancer and organ-specific cancer incidence.

RESULTS

During 11.8 years of follow-up, 23,450 (5.97%) and 23,413 (6.03%) incident cancers were included in the analyses of in utero exposure and age of smoking initiation, respectively. The HR (95% CI) for incident cancer in participants with in utero exposure to tobacco smoke was 1.04 (1.01-1.07) for overall cancer, 1.59 (1.44-1.75) for respiratory cancer, and 1.09 (1.03-1.17) for gastrointestinal cancer. The relative risk of incident cancer increased with earlier smoking initiation (Ptrend<.001), with the HR (95% CI) of 1.44 (1.36-1.51) for overall cancer, 13.28 (11.39-15.48) for respiratory cancer, and 1.72 (1.54-1.91) for gastrointestinal cancer in smokers with initiation in childhood compared with never smokers. Importantly, a positive additive interaction between age of smoking initiation and genetic risk was observed for overall cancer (Padditive=.04) and respiratory cancer (Padditive=.003) incidence.

CONCLUSION

In utero exposure and earlier smoking initiation are associated with overall and organ-specific cancer, and age of smoking initiation interaction with genetic risk is associated with respiratory cancer.

Socio-demographic and antenatal risk factors of brain tumor in children and young people: A matched case-control study from Karachi, Pakistan

Background

Brain tumors are a common cause of morbidity, disability, cognitive deterioration and mortality in children, even after treatment. Little is know about the specific causes. The study aimed to assess potential socio-demographic and antenatal factors in primary brain tumor (PBTs) in children and young people (CYP) in Karachi, Pakistan.

Designs and methods

A single center hospital based matched case control study in Karachi, Pakistan. Cases were defined as CYP aged between 5 and 21 years with any histological type and grade of primary brain tumor of any histology, stage or grade. Data were collected from parents of 244 patients at the selected center between 2017 and 2021 via telephonic interview. Controls were 5-21 years old CYP admitted with non-oncological diagnoses matched on age and sex. Matched Odds Ratios for predictors of brain tumor in children were derived. Those of statistical significance were included in a multivariable logistic regression model.

Results

In the adjusted model, lower paternal education (matched adjusted odds ratio (maOR) 2.46; 95% CI 1.09-5.55), higher household monthly income (maOR 3.4; 95% CI 1.1-10.2), antenatal paternal use of addictive substances (maOR 19.5; 95% CI 2.1-179.8), and antenatal maternal use of analgesics during pregnancy (maOR 3.0; 95% CI 1.2-7.9) were all independently predictive of brain tumors.

Conclusion

This matched case-control study found novel associations between maternal use of analgesics, paternal use of addictive substances, higher household income, and lower paternal education and Primary Brain Tumors in Children and Young People. Longitudinal multicenter studies will be required to test these associations prospectively.

Airway pollution and smoking in reproductive health

Environmental exposure refers to contact with chemical, biological, or physical substances found in air, water, food, or soil that may have a harmful effect on a person's health. Almost all of the global population (99%) breathe air that contains high levels of pollutants. Smoking is one of the most common forms of recreational drug use and is the leading preventable cause of morbidity and mortality worldwide. The small particles from either ambient (outdoor) pollution or cigarette smoke are inhaled to the lungs and quickly absorbed into the bloodstream. These substances can affect virtually every organ in our body and have been associated with various respiratory, cardiovascular, endocrine, and also reproductive morbidities, including decreased fertility, adverse pregnancy outcomes, and offspring long-term morbidity. This review summarizes the latest literature reporting the reproductive consequences of women exposed to ambient (outdoor) air pollution and cigarette smoking.

Parental Age and Childhood Lymphoma and Solid Tumor Risk: A Literature Review and Meta-Analysis

BACKGROUND

Although advanced parental age has been definitively linked to pediatric acute lymphoblastic leukemia, studies of parental age and pediatric solid tumors have not reached firm conclusions. This analysis aimed to elucidate the relationship between parental age and pediatric solid tumors through meta-analysis of existing studies based in population registries.

METHODS

We searched Medline (PubMed) and Embase for registry-based studies of parental age and solid tumors through March 2022. We performed random-effects meta-analysis to estimate pooled effects and 95% confidence intervals (CIs). All statistical tests were 2-sided.

RESULTS

A total of 15 studies covering 10 childhood solid tumor types (30 323 cases and 3 499 934 controls) were included in this analysis. A 5-year increase in maternal age was associated with an increased risk of combined central nervous system tumors (odds ratio [OR] = 1.07, 95% CI = 1.04 to 1.10), ependymoma (OR = 1.19, 95% CI = 1.09 to 1.31), astrocytoma (OR = 1.10, 95% CI = 1.05 to 1.15), rhabdomyosarcoma (OR = 1.14, 95% CI = 1.03 to 1.25), and germ cell tumors (OR = 1.06, 95% CI = 1.00 to 1.12). A 5-year increase in paternal age was associated with an increased risk of non-Hodgkin lymphoma (OR = 1.06, 95% CI = 1.00 to 1.12).

CONCLUSIONS

This meta-analysis of registry-based analyses of parental age and childhood cancer supports the association between older maternal age and certain childhood solid cancers. There is also some evidence that paternal age may be associated with certain cancers such as non-Hodgkin lymphoma. However, as maternal and paternal age are highly correlated, disentangling potential independent causal effects of either factor will require large studies with extensive data on potential confounders.

Maternal lifestyle factors and risk of neuroblastoma in the offspring: A meta-analysis including Greek NARECHEM-ST primary data

The etiology of childhood neuroblastoma remains largely unknown. In this systematic review and meta-analysis, we summarized and quantitatively synthesized published evidence on the association of maternal modifiable lifestyle factors with neuroblastoma risk in the offspring. We searched MEDLINE up to December 31, 2020 for eligible studies assessing the association of maternal smoking, alcohol consumption and nutritional supplementation during pregnancy with childhood (0-14 years) neuroblastoma risk. Random-effects models were run, and summary odds ratios (OR) and 95% confidence intervals (95% CI) on the relevant associations were calculated, including estimates derived from primary data (n = 103 cases and n = 103 controls) of the Nationwide Registry for Childhood Hematological Malignancies and Solid Tumors (NARECHEM-ST) case control study (2009-2017) in Greece. Twenty-one eligible studies amounting 5163 cases participating in both case-control and cohort/linkage studies were included in the meta-analysis. Maternal smoking and alcohol consumption were not statistically significantly associated with neuroblastoma risk (summary ORsmoking: 1.08, 95% CI: 0.96-1.22, I2 =12.0%, n = 17 studies; summary ORalcohol: 1.01, 95% CI: 0.82-1.18, I2 =0.0%, n = 8 studies). By contrast, maternal vitamin intake during pregnancy was associated with significantly lower neuroblastoma risk (summary OR: 0.57, 95% CI: 0.34-0.95, I2 =58.9%, n = 4 studies). The results of the largest to-date meta-analysis point to an inverse association between vitamin intake during pregnancy and childhood neuroblastoma risk. Future longitudinal studies are needed to confirm and further specify these associations as to guide preventive efforts on modifiable maternal risk factors of childhood neuroblastoma.

The role of diet in renal cell carcinoma incidence: an umbrella review of meta-analyses of observational studies

BACKGROUND

Evidence associating diet with the incidence of renal cell carcinoma (RCC) is inconclusive. We aimed to summarize evidence associating dietary factors with RCC incidence and assess the strength and validity of this evidence.

METHODS

We conducted an umbrella review of systematic reviews or meta-analyses (SRoMAs) that assessed the association between diet and RCC incidence. Through April 2021, PubMed, Web of Science, Embase, The Cochrane Library, Scopus, and WCRF were searched. Two independent reviewers selected studies, extracted data, and appraised the quality of SRoMAs. According to credibility assessment criteria, evidence can be divided into five categories: convincing (class I), highly suggestive (class II), suggestive (class III), weak (class IV), and nonsignificant (class V).

RESULTS

Twenty-nine meta-analyses were obtained after screening. After excluding 7 overlapping meta-analyses, 22 meta-analyses including 502 individual studies and 64 summary hazard ratios for RCC incidence were included: dietary patterns or dietary quality indices (n = 6), foods (n = 13), beverages (n = 4), alcohol (n = 7), macronutrients (n =15), and micronutrients (n =19). No meta-analyses had high methodological quality. Five meta-analyses exhibited small study effects; one meta-analysis showed evidence of excess significance bias. No dietary factors showed convincing or highly suggestive evidence of association with RCC in the overall analysis. Two protective factors had suggestive evidence (vegetables (0.74, 95% confidence interval 0.63 to 0.86) and vitamin C (0.77, 0.66 to 0.90)) in overall analysis. One protective factor had convincing evidence (moderate drinking (0.77, 0.70 to 0.84)) in Europe and North America and one protective factor had highly suggestive evidence (cruciferous vegetables (0.78, 0.70 to 0.86)) in North America.

CONCLUSIONS

Although many meta-analyses have assessed associations between dietary factors and RCC, no high-quality evidence exists (classes I and II) in the overall analysis. Increased intake of vegetables and vitamin C is negatively associated with RCC risk. Moderate drinking might be beneficial for Europeans and North Americans, and cruciferous vegetables might be beneficial to North Americans, but the results should be interpreted with caution. More researches are needed in the future.

TRIAL REGISTRATION

PROSPERO CRD42021246619.

The relationship between congenital heart disease and cancer in Swedish children: A population-based cohort study

BACKGROUND

Birth defects have been consistently associated with elevated childhood cancer risks; however, the relationship between congenital heart disease (CHD) and childhood cancer remains conflicting. Considering the increasing patient population with CHD after improvements in their life expectancies, insights into this relationship are particularly compelling. Thus, we aimed to determine the relationship between CHD and cancer in Swedish children.

METHODS AND FINDINGS

All individuals registered in the Swedish Medical Birth Register (MBR) between 1973 and 2014 were included in this population-based cohort study (n = 4,178,722). Individuals with CHD (n = 66,892) were identified from the MBR and National Patient Register, whereas cancer diagnoses were retrieved from the Swedish Cancer Register. The relationship between CHD and childhood cancer (<20 years at diagnosis) was evaluated using Cox proportional hazards regression models. We observed increased risks of cancer overall, leukemia, lymphoma, and hepatoblastoma in children with CHD, but after adjustment for Down syndrome, only the increased lymphoma (hazard ratio (HR) = 1.64, 95% confidence interval (CI) 1.11 to 2.44) and hepatoblastoma (HR = 3.94, 95% CI 1.83 to 8.47) risk remained. However, when restricting to CHD diagnoses from the MBR only, i.e., those diagnosed around birth, the risk for childhood cancer overall (HR = 1.45, 95% CI 1.23 to 1.71) and leukemia (HR = 1.41, 95% CI 1.08 to 1.84) was more pronounced, even after controlling for Down syndrome. Finally, a substantially elevated lymphoma risk (HR = 8.13, 95% CI 4.06 to 16.30) was observed in children with complex CHD. Limitations of the study include the National Patient Register not being nationwide until 1987, in addition to the rareness of the conditions under study providing limited power for analyses on the rarer cancer subtypes.

CONCLUSIONS

We found associations between CHD and childhood lymphomas and hepatoblastomas not explained by a diagnosis of Down syndrome. Stronger associations were observed in complex CHD.

DNA damage analysis in newborns and their mothers related to pregnancy and delivery characteristics

INTRODUCTION

Increased DNA damage is associated with early events in carcinogenesis. The foetus may be more susceptible to effects of environment by transplacental exposure. We aimed to evaluate DNA damage in cells from umbilical cord (arteries and vein) and maternal blood from pregnant women.

METHODS

Fifty eight pregnant women and their offspring were included in this study. They were submitted to an interview to obtain information about personal history, clinical history, and lifestyle habits. Other Information was obtained from medical records. The samples were prepared for Single Cell Gel/Comet assay and Cytokinesis-block Micronucleus Cytome (CBMN-Cyt) assay.

RESULTS

Correlation between DNA damage frequency by Comet assay from newborns and their mothers was statistically significant and was significantly associated with nulliparity and more than 1 h of second stage of labour (umbilical vein and maternal blood). A positive MNi relationship was noticed for age (mother's blood) and inappropriate birth weight for gestational age (maternal blood). When multivariate statistical analyses were applied to measure the degree of association between variables that influenced DNA damage markers in the first evaluation, inadequate birth weight and pregnant weight gain were associated with MNi frequency in maternal and newborns blood, respectively.

DISCUSSION

Significant associations between DNA damage in newborns and pregnant women, and birth and pregnancy events suggest molecular evidence of transplacental genotoxic effects. However, a potentially increased risk of degenerative diseases, such as cancers, in this population should be carefully investigated by further prospective cohort studies.

Early life exposure to tobacco smoke and ovarian cancer risk in adulthood

BACKGROUND

Ovarian cancer risk in adulthood may be affected by early life exposure to tobacco smoke. We investigated this relationship in two large prospective cohorts, the Nurses' Health Study (NHS) and NHSII.

METHODS

In total, analyses included 110 305 NHS participants (1976-2016) and 112 859 NHSII participants (1989-2017). Self-reported early life smoking exposures were queried at baseline or follow-up questionnaires. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of ovarian cancer overall and by tumour histotype.

RESULTS

Overall, ovarian cancer risk was not different among participants whose mothers did versus did not smoke during pregnancy (HR = 1.05, 95% CI: 0.87-1.27); however, an increased risk was observed among women who themselves were never smokers (HR = 1.38, 95% CI: 1.05-1.81) but not among ever smokers (HR = 0.86, 95% CI: 0.66-1.14; Pheterogeneity = 0.02). Compared with women who never smoked, ovarian cancer risk was similar for women who started to smoke at age <18 (HR = 0.98, 95% CI: 0.86-1.11) or ≥18 (HR = 1.02, 95% CI: 0.93-1.12). These associations did not differ by histotype (Pheterogeneity ≥0.35). Parental smoking in the home during childhood/adolescence was related to a 15% increased risk of ovarian cancer in adulthood (HR = 1.15, 95% CI: 1.04-1.27) and this association was suggestively stronger among women with non-serous/low-grade serous tumours (HR = 1.28, 95% CI: 1.02-1.61) versus high-grade serous/poorly differentiated tumours (HR = 1.09, 95% CI: 0.93-1.28; Pheterogeneity = 0.25).

CONCLUSIONS

Exposure to parental tobacco smoke in the home, but not early initiation of smoking, was associated with a modest elevated risk of ovarian cancer. Further investigations are required to confirm these findings and elucidate underlying mechanisms.

RUNX1 gene expression changes in the placentas of women smokers

The placenta can be affected by environmental factors, such as exposure to cigarette smoke. This exposure in the fetal context is considered a risk factor for the development of short-term postnatal diseases, such as asthma. Asthma is an inflammatory disease characterized by predominant acquisition of CD4 T lymphocytes (TLs) of the Th2 type. Transcription factors such as GATA binding protein 3 (GATA3) and STAT6 actively participate in the differentiation of virgin TLs towards the Th2 profile, while transcription factors such as STAT1, T-Box transcription factor 21 (T-BET), RUNX1 and RUNX3 participate in their differentiation towards the Th1 profile. The objective of the current study was to evaluate the impact of exposure to cigarette smoke on the gene expression of STAT1, T-BET, GATA3, IL-4, RUNX1 and RUNX3 during the gestation period, and to determine whether the expression levels of these genes are associated with changes in global methylation. STAT1, GATA3, RUNX1 and RUNX3 protein and mRNA expression levels in the placental tissue of women smokers and non-smoking women were determined via immunohistochemistry and quantitative PCR (qPCR) respectively. Additionally, T-BET and IL-4 mRNA expression levels were determined by qPCR. On the other hand, global methylation was determined via ELISA. In the present study, significant increases were observed in RUNX1 transcription factor expression in placentas from women smokers when compared with placentas of non-smoking women. Similarly, significant increases in the expression of GATA3, IL-4 and RUNX3 mRNA were observed. The changes in gene expression were not associated with changes in the global methylation levels. Finally, a higher frequency of low-birth-weight infants were identified in cases of exposure to cigarette smoke during pregnancy when compared with infants not exposed to cigarette smoke during pregnancy. Thus, the data of the present study contributed to the understanding of the genetic and clinical impacts of exposure to cigarette smoke during pregnancy and its importance in maternal and fetal health.

Methylation marks of prenatal exposure to maternal smoking and risk of cancer in adulthood

BACKGROUND

Prenatal exposure to maternal smoking is detrimental to child health but its association with risk of cancer has seldom been investigated. Maternal smoking induces widespread and long-lasting DNA methylation changes, which we study here for association with risk of cancer in adulthood.

METHODS

Eight prospective case-control studies nested within the Melbourne Collaborative Cohort Study were used to assess associations between maternal-smoking-associated methylation marks in blood and risk of several cancers: breast (n = 406 cases), colorectal (n = 814), gastric (n = 166), kidney (n = 139), lung (n = 327), prostate (n = 847) and urothelial (n = 404) cancer and B-cell lymphoma (n = 426). We used conditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations between cancer and five methylation scores calculated as weighted averages for 568, 19, 15, 28 and 17 CpG sites. Models were adjusted for confounders, including personal smoking history (smoking status, pack-years, age at starting and quitting) and methylation scores for personal smoking.

RESULTS

All methylation scores for maternal smoking were strongly positively associated with risk of urothelial cancer. Risk estimates were only slightly attenuated after adjustment for smoking history, other potential confounders and methylation scores for personal smoking. Potential negative associations were observed with risk of lung cancer and B-cell lymphoma. No associations were observed for other cancers.

CONCLUSIONS

We found that methylation marks of prenatal exposure to maternal smoking are associated with increased risk of urothelial cancer. Our study demonstrates the potential for using DNA methylation to investigate the impact of early-life, unmeasured exposures on later-life cancer risk.

Pediatric Rhabdomyosarcoma: Epidemiology and Genetic Susceptibility

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in children, yet little is known about its etiology. Studies that examine either environmental exposures or germline genetic predisposition in RMS have begun to identify factors that contribute to this malignancy. Here, we summarize epidemiological reports of RMS incidence in terms of several factors, including age at diagnosis, biological sex, and geographic location. We then describe findings from association studies, which explore the role of parental exposures, birth and perinatal characteristics, and childhood exposures in RMS. Further, we discuss RMS predisposition syndromes and large-scale sequencing studies that have further identified RMS-associated genes. Finally, we propose future directions of study, which aim to advance our understanding of the origin of RMS and can provide knowledge for novel RMS therapies.

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.

Health outcomes of smoking during pregnancy and the postpartum period: an umbrella review

BACKGROUND

Smoking during pregnancy (SDP) and the postpartum period has serious health outcomes for the mother and infant. Although some systematic reviews have shown the impact of maternal SDP on particular conditions, a systematic review examining the overall health outcomes has not been published. Hence, this paper aimed to conduct an umbrella review on this issue.

METHODS

A systematic review of systematic reviews (umbrella review) was conducted according to a protocol submitted to PROSPERO ( CRD42018086350 ). CINAHL, EMBASE, MEDLINE, PsycINFO, Web of Science, CRD Database and HMIC databases were searched to include all studies published in English by 31 December 2017, except those focusing exclusively on low-income countries. Two researchers conducted the study selection and quality assessment independently.

RESULTS

The review included 64 studies analysing the relationship between maternal SDP and 46 health conditions. The highest increase in risks was found for sudden infant death syndrome, asthma, stillbirth, low birth weight and obesity amongst infants. The impact of SDP was associated with the number of cigarettes consumed. According to the causal link analysis, five mother-related and ten infant-related conditions had a causal link with SDP. In addition, some studies reported protective impacts of SDP on pre-eclampsia, hyperemesis gravidarum and skin defects on infants. The review identified important gaps in the literature regarding the dose-response association, exposure window, postnatal smoking.

CONCLUSIONS

The review shows that maternal SDP is not only associated with short-term health conditions (e.g. preterm birth, oral clefts) but also some which can have life-long detrimental impacts (e.g. obesity, intellectual impairment).

IMPLICATIONS

This umbrella review provides a comprehensive analysis of the overall health impacts of SDP. The study findings indicate that while estimating health and cost outcomes of SDP, long-term health impacts should be considered as well as short-term effects since studies not including the long-term outcomes would underestimate the magnitude of the issue. Also, interventions for pregnant women who smoke should consider the impact of reducing smoking due to health benefits on mothers and infants, and not solely cessation.

Social gradient predicts survival disadvantage of African Americans/Black children with lymphoma

BACKGROUND

Cancer is the leading cause of disease-related mortality among children, 0-14 years, and lymphoma, a malignant neoplasm of the lymphoid cells, mostly lymphatic B and T cells is common among children. The current study aimed to assess the cumulative incidence (CmI), mortality, and survival in pediatric lymphoma.

MATERIALS AND METHODS

A retrospective cohort was utilized to examine children, 0-19 years with lymphoma for CmI, mortality and survival from the Surveillance, Epidemiology, and End Results (SEER) data. The variables assessed included social determinants of health, namely urbanity, median household income, and race. While chi square was used to characterize study variables by race, binomial regression was employed for mortality risk. The Cox proportional hazard model was used for survival modeling.

RESULTS

The CmI was higher among white children (76.67%) relative to Black/African American (AA, 13.44%), American Indian/Alaskan Native (AI/AN, 0.67%), as well as Asian/Pacific Islander (A/PI, 7.53%). With respect to mortality, there was excess mortality among Black/AA children compared to white children, Risk Ratio (RR) = 1.54, 95% CI, 1.33-1.79. Relative to whites, Blacks were 52% more likely to die, Hazard Ratio (HR) = 1.52, 95% CI, 1.30-1.78. Survival disadvantage persisted among Blacks/AA after controlling for the other confoundings, adjusted hazard ratio (aHR) = 1.54, 99% CI, 1.24-1.91.

CONCLUSION

In a large cohort of children with lymphoma, Black/AA children relative to whites presented with survival disadvantage, which was explained by urbanity and median household income, suggestive of transforming the physical and social environments in narrowing the racial differences in pediatric lymphoma survival in the US.

Incentives for Smoking Cessation During Pregnancy: An Ethical Framework

Introduction

Smoking during pregnancy increases the risk of morbidity and mortality of the mother and child. The inability of the unborn child to protect itself, raises the social and academic responsibility to protect the child from the harmful effects of smoking. Interventions including rewards (incentives) for lifestyle changes are an upcoming trend and can encourage women to quit smoking. However, these incentives can, as we will argue, also have negative consequences, for example the restriction of personal autonomy and encouragement of smoking to become eligible for participation. To prevent these negative consequences, we developed an ethical framework that enables to assess and address unwanted consequences of incentive-based interventions whereby moral permissibility can be evaluated.

Aims and Methods

The possible adverse consequences of incentives were identified through an extensive literature search. Subsequently, we developed ethical criteria to identify these consequences based on the biomedical ethical principles of Beauchamp and Childress.

Results

Our framework consists of 12 criteria. These criteria concern (1) effectiveness, (2) support of a healthy lifestyle, (3) motivational for the target population, (4) stimulating unhealthy behavior, (5) negative attitudes, (6) personal autonomy, (7) intrinsic motivation, (8) privacy, (9) fairness, (10) allocation of incentives, (11) cost-effectiveness, and (12) health inequity. Based on these criteria, the moral permissibility of potential interventions can be evaluated.

Conclusions

Incentives for smoking cessation are a response to the responsibility to protect the unborn child. But these interventions might have possible adverse effects. This ethical framework aims to identify and address ethical pitfalls in order to avoid these adverse effects.

Implications

Although various interventions to promote smoking cessation during pregnancy exist, many women still smoke during pregnancy. Interventions using incentives for smoking cessation during pregnancy are a promising and upcoming trend but can have unwanted consequences. This ethical framework helps to identify and address ethical pitfalls in order to avoid these adverse effects.

It can be a practical tool in the development and evaluation of these interventions and in evaluating the moral permissibility of interventions using incentives for smoking cessation during pregnancy.

Immediate and durable effects of maternal tobacco consumption alter placental DNA methylation in enhancer and imprinted gene-containing regions

BACKGROUND

Although exposure to cigarette smoking during pregnancy has been associated with alterations of DNA methylation in the cord blood or placental cells, whether such exposure before pregnancy could induce epigenetic alterations in the placenta of former smokers has never been investigated.

METHODS

Our approach combined the analysis of placenta epigenomic (ENCODE) data with newly generated DNA methylation data obtained from 568 pregnant women, the largest cohort to date, either actively smoking during their pregnancy or formerly exposed to tobacco smoking.

RESULTS

This strategy resulted in several major findings. First, among the 203 differentially methylated regions (DMRs) identified by the epigenome-wide association study, 152 showed "reversible" alterations of DNA methylation, only present in the placenta of current smokers, whereas 26 were also found altered in former smokers, whose placenta had not been exposed directly to cigarette smoking. Although the absolute methylation changes were smaller than those observed in other contexts, such as in some congenital diseases, the observed alterations were consistent within each DMR. This observation was further supported by a demethylation of LINE-1 sequences in the placentas of both current (beta-coefficient (β) (95% confidence interval (CI)), - 0.004 (- 0.008; 0.001)) and former smokers (β (95% CI), - 0.006 (- 0.011; - 0.001)) compared to nonsmokers. Second, the 203 DMRs were enriched in epigenetic marks corresponding to enhancer regions, including monomethylation of lysine 4 and acetylation of lysine 27 of histone H3 (respectively H3K4me1 and H3K27ac). Third, smoking-associated DMRs were also found near and/or overlapping 10 imprinted genes containing regions (corresponding to 16 genes), notably including the NNAT, SGCE/PEG10, and H19/MIR675 loci.

CONCLUSIONS

Our results pointing towards genomic regions containing the imprinted genes as well as enhancers as preferential targets suggest mechanisms by which tobacco could directly impact the fetus and future child. The persistence of significant DNA methylation changes in the placenta of former smokers supports the hypothesis of an "epigenetic memory" of exposure to cigarette smoking before pregnancy. This observation not only is conceptually revolutionary, but these results also bring crucial information in terms of public health concerning potential long-term detrimental effects of smoking in women.

Maternal lifestyle characteristics and Wilms tumor risk in the offspring: A systematic review and meta-analysis

BACKGROUND

Little is known about the etiology of childhood Wilms tumor (WT) and potentially modifiable maternal risk factors, in particular.

METHODS

Unpublished data derived from the hospital-based, case-control study of the Greek Nationwide Registry for Childhood Hematological Malignancies and Solid Tumors (NARECHEM-ST) were included in an ad hoc conducted systematic literature review and meta-analyses examining the association between modifiable maternal lifestyle risk factors and WT. Eligible data were meta-analysed in separate strands regarding the associations of WT with (a) maternal folic acid and/or vitamins supplementation, (b) alcohol consumption and (c) smoking during pregnancy. The quality of eligible studies was evaluated using the Newcastle-Ottawa Scale.

RESULTS

Effect estimates from 72 cases and 72 age- and sex-matched controls contributed by NARECHEM-ST were meta-analysed together with those of another 17, mainly medium size, studies of ecological, case-control and cohort design. Maternal intake of folic acid and/or other vitamins supplements during pregnancy was inversely associated with WT risk (6 studies, OR: 0.78; 95 %CI: 0.69-0.89, I2 = 5.4 %); of similar size was the association for folic acid intake alone (4 studies, OR: 0.79; 95 %CI: 0.69-0.91, I2 = 0.0 %), derived mainly from ecological studies. In the Greek study a positive association (OR: 5.31; 95 %CI: 2.00-14.10) was found for mothers who consumed alcohol only before pregnancy vs. never drinkers whereas in the meta-analysis of the four homogeneous studies examining the effect of alcohol consumption during pregnancy the respective overall result showed an OR: 1.60 (4 studies, 95 %CI: 1.28-2.01, I2 = 0.0 %). Lastly, no association was seen with maternal smoking during pregnancy (14 studies, OR: 0.93; 95 %CI: 0.80-1.09, I2 = 0.0 %).

CONCLUSIONS

In the largest to-date meta-analysis, there was an inverse association of maternal folic acid or vitamins supplementation with WT risk in the offspring, derived mainly from ecological studies. The association with maternal alcohol consumption found in our study needs to be further explored whereas no association with maternal smoking was detected. Given the proven benefits for other health conditions, recommendations regarding folic acid supplementation as well as smoking and alcohol cessation should apply. The maternal alcohol consumption associations, however, should be further explored given the inherent limitations in the assessment of exposures of the published studies.

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.

[In Utero Exposure to Maternal Smoking: Impact on the Child from Birth to Adulthood - CNGOF-SFT Expert Report and Guidelines for Smoking Management during Pregnancy]

INTRODUCTION

Smoking during pregnancy leads to fetal passive smoking. It is associated with several obstetrical complications and is a major modifiable factor of maternal and fetal morbidity. Long-term consequences also exist but are less well known to health professionals and in the general population.

METHODS

Consultation of the Medline® database.

RESULTS

Maternal smoking during pregnancy is associated in the offspring with sudden infant death syndrome (NP2), impaired lung function (NP2), lower respiratory infections and asthma (NP2), overweight and obesity (NP2), cancers (NP3), risk of tobacco use, nicotine dependence and early smoking initiation (NP2). Unadjusted analyses show associations between in utero tobacco exposure and cognitive deficits (NP3), impaired school performance (NP3) and behavioral disorders in children (NP2), which are in a large part explained by environmental factors. There is a cross-generational effect of smoking during pregnancy. For example, an increased risk of asthma is observed in the grandchildren of smoking women (NP4). The respective roles of ante- and post-natal smoking remain difficult to assess.

CONCLUSION

These results highlight the importance of prevention measures against tobacco use in the general population, as well as screening measures and support for smoking cessation before or at the beginning of the pregnancy.

Parental tobacco smoking and risk of childhood leukemia in Costa Rica: A population-based case-control study

INTRODUCTION

The role of environmental and behavioral exposures on childhood leukemia etiology is poorly understood. We examined the association of maternal and paternal tobacco smoking at different time points with the risk of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) in Costa Rican children.

MATERIALS AND METHODS

We conducted a population-based case-control study on childhood leukemia in Costa Rica. Cases (n ALL = 252; n AML = 40) were diagnosed between 1995 and 2000 (aged <15 years at diagnosis) and identified from the Costa Rican Cancer Registry and the National Children's Hospital. A total of 578 frequency-matched population controls were sampled from the National Birth Registry. Parental tobacco smoking was assessed via face-to-face interviews. We used logistic regression models to examine the association of paternal and maternal tobacco smoking before conception, during pregnancy, and after birth with childhood ALL and AML risk, adjusted for child sex, birth year, maternal/paternal age, and parental education.

RESULTS

Paternal smoking before conception, during pregnancy, and after birth was associated with an increased risk of childhood AML (Odds Ratio (OR): 2.51, 95% CI: 1.21-5.17; OR: 3.21, 95% CI: 1.56-6.60; and OR: 2.83, 95% CI: 1.36-5.90, respectively). Maternal smoking during pregnancy was also associated with a modest, but imprecise increase in AML risk. We observed null associations of maternal and paternal smoking with ALL in the offspring.

CONCLUSION

Our results suggest an association between parental smoking and risk of AML, but not ALL, in Costa Rican children. These findings add to the established evidence of numerous health risks associated with smoking and highlight the potential harm of smoking during sensitive windows of the development of fetus and child.

Exploring a potential mechanistic role of DNA methylation in the relationship between in utero and post-natal environmental exposures and risk of childhood acute lymphoblastic leukaemia

The aetiology of childhood acute lymphoblastic leukaemia (ALL) is unclear. Genetic abnormalities have been identified in a number of ALL cases, although these alone are not sufficient for leukaemic transformation. Various in utero and post-natal environmental exposures have been suggested to alter risk of childhood ALL. DNA methylation patterns can be influenced by environmental exposures, and are reported to be altered in ALL, suggesting a potential mediating mechanism between environment and ALL disease risk. To investigate this, we used a 'meet in the middle' approach, investigating the overlap between exposure-associated and disease-associated methylation change. Genome-wide DNA methylation changes in response to possible ALL-risk exposures (i.e. breast feeding, infection history, day care attendance, maternal smoking, alcohol, caffeine, folic acid, iron and radiation exposure) were investigated in a sub-population of the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort using an epigenome-wide association study (EWAS) approach (n = 861-927), and compared to a list of ALL disease-associated methylation changes compiled from published data. Hypergeometric probability tests suggested that the number of directionally concordant gene methylation changes observed in ALL disease and in response to the following exposures; maternal radiation exposure (p = 0.001), alcohol intake (p = 0.006); sugary caffeinated drink intake during pregnancy (p = 0.045); and infant day care attendance (p = 0.003), were not due to chance. Data presented suggests that DNA methylation may be one mediating mechanism in the multiple hit pathway needed for ALL disease manifestation.

Second follow-up of a German cohort on childhood cancer incidence after exposure to postnatal diagnostic x-ray

Studies on children exposed to ionising radiation by computed tomography (CT) indicate an increased risk of leukemia and central nervous system (CNS) tumors. Evidence of the risks associated with diagnostic x-ray examinations, the most frequent examination in pediatric radiology, in which the radiation dose is up to 750 times lower compared to CT examinations, is less clear. This study presents results of the second follow-up for the risk of childhood cancer in a cohort of children (<15 years) with diagnostic x-ray exposure at a large German hospital during 1976-2003 followed for additional 10 years until 2016. With a latency period of 6 months, 92 998 children contributed 794 549 person-years. The median effective dose was 7 μSv. Hundred incident cancer cases were identified: 35 leukemia, 13 lymphomas, 12 CNS tumors, 15 blastomas, 15 sarcomas and 10 other solid tumors, consisting of six germ cells tumors, three thyroid cancers and one adrenocortical carcinoma. For all cancer cases combined the standardised incidence ratio (SIR) was 1.14 (95% confidence interval (CI) 0.93-1.39), for leukemia 1.15 (95% CI 0.63-1.61), for lymphomas 1.03 (95% CI 0.55-1.76), for CNS tumors 0.65 (95% CI 0.34-1.14), for blastomas 1.77 (95% CI 0.91-2.91), for sarcomas 1.28 (95% CI 0.71-2.11) and for other solid tumors 2.38 (95% CI 1.14-4.38). Dose-response analysis using Poisson regression revealed no significant trend for dose groups. Results did not differ substantially with a latency period of 2 years for all cancer entities and 5 years for solid tumors in sensitivity analyses. Overall, the null results of the first follow-up were confirmed. Although an association between radiation exposure and a risk for certain solid tumors like thyroid cancer is known, the significantly increased SIR in the group of other solid tumors must be critically interpreted in the context of the small number of cases and the very low doses of radiation exposure in this group.

Transplacental exposure to carcinogens and risks to children: evidence from biomarker studies and the utility of omic profiling

The factors underlying the increasing rates and the geographic variation of childhood cancers are largely unknown. Epidemiological studies provide limited evidence for a possible role in the etiology of certain types of childhood cancer of the exposure of pregnant women to environmental carcinogens (e.g., tobacco smoke and pesticides); however, such evidence is inadequate to allow definitive conclusions. Complementary evidence can be obtained from biomarker-based population studies. Such studies have demonstrated that, following exposure of pregnant mothers, most environmental carcinogens reach the fetus and, in many cases, induce therein genotoxic damage which in adults is known to be associated with increased cancer risk, implying that environmental carcinogens may contribute to the etiology of childhood cancer. During recent years, intermediate disease biomarkers, obtained via omic profiling, have provided additional insights into the impact of transplacental exposures on fetal tissues which, in some cases, are also compatible with a precarcinogenic role of certain in utero exposures. Here we review the epidemiological and biomarker evidence and discuss how further research, especially utilizing high-density profiling, may allow a better evaluation of the links between in utero environmental exposures and cancer in children.

The effect of maternal tobacco smoking and second-hand tobacco smoke exposure on human milk oxidant-antioxidant status

BACKGROUND

Many women who smoke tobacco continue to do so during lactation, and many non-smoking women are exposed to second-hand tobacco smoke (SHS) during the period that she wishes to breastfeed. There are reports documenting the adverse effects of maternal smoking during lactation on their infant's health; however, the pathophysiological mechanisms underlying these effects are incompletely understood.

OBJECTIVES

Our study purpose was to examine the influence of tobacco smoke on biochemical markers reflecting the intensity of oxidative stress using concentration of total protein (TP), trolox equivalent antioxidant capacity (TEAC), S-nitrosothiols (RSNO), nitric oxide (NO), thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), glutathione S-transferase (GST), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) in the plasma, colostrum, and mature milk of women who smoke, those only exposed to SHS, and non-smokers.

METHODS

Questionnaire data on the tobacco smoking status were verified based on the determination of cotinine by high performance liquid chromatography with diode array detector (HPLC-DAD). Relevant markers of oxidative stress and biochemical parameters were determined using spectrophotometric methods.

RESULTS

We found that tobacco smoking during lactation increases oxidative stress in the mother's plasma, colostrum, and mature milk, and lesser so in those exposed to SHS. Tobacco smoke significantly increase TBARS and decrease TEAC in colostrum and mature milk. In response to ROS generated by tobacco smoke increase the activity of antioxidant enzymes (SOD, GST, GPx and CAT), p < 0.05.

DISCUSSION

Such exposure to tobacco smoke influences the antioxidant barrier of human colostrum and mature milk that can adversely affect their infant's health. Greater public health awareness of the adverse effects of tobacco smoking during lactation on breast milk quality and its protective effects is urgently needed.

Smoking habit from the paternal line and grand-child's overweight or obesity status in early childhood: prospective findings from the lifeways cross-generation cohort study

BACKGROUND/OBJECTIVES

The role of smoking from the paternal line during the pre-conception period on grand-child's overweight/obesity and associated underlying pathways are uncertain. We examined whether the smoking status from the paternal line was associated with the grand-child's higher weight at birth, and overweight or obesity at 5 and 9 years of age. The grandparental smoking effect from the maternal line was also explored.

SUBJECTS/METHODS

Participants were fathers and grandparents and grand-children from the Lifeways Cross Generational Cohort (N = 1021 for the analysis at birth; N = 562 and N = 284 for the analysis at 5 and 9 years, respectively). Paternal and grandparental smoking was defined as smoking versus non-smoking. Children's weight categories compared were high versus normal weight at birth, and overweight/obesity versus normal weight (based on BMI and waist circumference) at age of five and nine years. Logistic regression models were used to estimate the crude and adjusted associations.

RESULTS

After adjustment for several child and parental factors, at age five there was an association between paternal smoking and offspring's overweight/obesity based on BMI (Adjusted Odds Ratio (AOR), and 95%CI: 1.76, 1.14-2.71, p-value: 0.010), most marked for boys (AOR: 2.05, 1.06-3.96, p-value: 0.032). These associations remained when confined to the children sample with biological fathers only (overall sample, AOR: 1.92, 1.22-3.02, p-value: 0.005; son, AOR: 2.09, 1.06-4.11, p-value: 0.033). At age 9, the paternal grandmothers' smoking was positively associated with their grandchild's overweight/obesity status based on waist circumference (AOR: 3.29, 1.29-8.37), and especially with that of her granddaughter (AOR: 3.44, 1.11-10.69). These associations remained when analysing only the children sample with biological fathers (overall sample, AOR: 3.22,1.25-8.29, p-value: 0.016; granddaughter, AOR: 3.55, 1.13-11.15, p-value: 0.030).

CONCLUSION

The smoking habit from the paternal line is associated with grand-children's adiposity measures during their early childhood, which might be epigenetically transmitted through male-germline cells.

The MATEX cohort - a Finnish population register birth cohort to study health effects of prenatal exposures

Background

The prevalence of chronic diseases, such as immune, neurobehavioral, and metabolic disorders has increased in recent decades. According to the concept of Developmental Origin of Health and Disease (DOHaD), developmental factors associated with environmental exposures and maternal lifestyle choices may partly explain the observed increase. Register-based epidemiology is a prime tool to investigate the effects of prenatal exposures over the whole life course.

Our aim is to establish a Finnish register-based birth cohort, which can be used to investigate various (prenatal) exposures and their effects during the whole life course with first analyses focusing on maternal smoking and air pollution. In this paper we (i) review previous studies to identify knowledge gaps and overlaps available for cross-validation, (ii) lay out the MATEX study plan for register linkages, and (iii) analyse the study power of the baseline MATEX cohort for selected endpoints identified from the international literature.

Methods/design

The MATEX cohort is a fully register-based cohort identified from the Finnish Medical Birth Register (MBR) (1987–2015). Information from the MBR will be linked with other Finnish health registers and the population register to link the cohort with air quality data. Epidemiological analyses will be conducted for maternal smoking and air pollution and a range of health endpoints.

Discussion

The MATEX cohort consists of 1.75 million mother-child pairs with a maximum follow up time of 29 years. This makes the cohort big enough to reach sufficient statistical power to investigate rare outcomes, such as birth anomalies, childhood cancers, and sudden infant death syndrome (SIDS). The linkage between different registers allows for an extension of the scope of the cohort and a follow up from the prenatal period to decades later in life.

Electronic supplementary material

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The short-term effect of smoking on fetal ECG

BACKGROUND

The number of women who smoke during pregnancy is significant even today. The harmful effects of smoking during pregnancy are well known but there are no data on the effects of smoking on fetal electrocardiography (ECG). The lack of data is in connection with the difficulties of recording fetal ECG through the maternal abdomen.

METHOD

Third trimester pregnant women who were not able to give up the harmful passion of smoking despite repeated attempts of persuasion were recruited in the study on voluntary basis. The fetal ECG was recorded non-invasively through the maternal abdomen before, during and after smoking, then the data were processed offline. The electrophysiological measurements were performed by a self developed ECG device, which allowed the examination of the morphological differences in "true-to-form" fetal ECG in addition to studying the variability of fetal heart rate. The study involved nine pregnant women. The observed changes are presented through case studies of those pregnant women who showed the most significant anomalies.

RESULTS

Compared with the resting state fetal heart rate was increased during smoking. The short-term variability of fetal heart rate was narrowed, while the mother's heart rate did not change significantly - which was an indication of direct fetal stress. No explicit ischemic signs were detected in fetal ECG during smoking, however, in the increasing period of the fetal heart rate, the T wave morphology changed slightly, then it returned to normal.

CONCLUSIONS

Demonstrable by the electrophysiological methods, smoking has a direct effect on fetal cardiac function. The fetal heart rate variability shows a pattern during smoking which is a typical sign of stress conditions among adults. The results may have educational consequences as well. Understanding those, hopefully will help pregnant women give up this harmful addiction.

Transplacental exposure to environmental carcinogens: Association with childhood cancer risks and the role of modulating factors

Biological responses to carcinogens from environmental exposure during adulthood are modulated over years or decades. Conversely, during transplacental exposure, the effects on the human foetus change within weeks, intertwining with developmental mechanisms: even short periods of transplacental exposure may be imprinted in the organism for a lifetime. The pathways leading to childhood and juvenile cancers, such as leukaemias, neuroblastoma/brain tumours, hepatoblastoma, and Willm's tumour involve prenatally-induced genomic, epigenomic and/or non-genomic effects caused by xenobiotics. Pregnant women most often live in complex environmental settings that cause transplacental exposure of the foetus to xenobiotic mixtures. Mother-child biomonitoring should integrate the analysis of chemicals/radiation present in the living and workplace environment with relevant risk modulators related to life style. The interdisciplinary approach for transplacental cancer risk assessment in high-pressure areas should be based on an integrated model for mother-child exposure estimation via profiling the exposure level by water quality analysis, usage of emission grids, and land use maps.