Pregnancy, maternal tobacco smoking, and early age leukemia in Brazil

Pediatric leukemia and maternal occupational exposure to anticancer drugs: the Japan Environment and Children's Study

ABSTRACT

Occupational exposure to medical agents and ionizing radiation has been suggested as a possible risk factor for childhood cancer. However, the relationship between such exposure and pediatric malignant neoplasms has not yet been comprehensively studied. This cohort study aimed to investigate the association between parental occupational exposure to hazardous medical agents or ionizing radiation and the risk of childhood cancer in offspring. Data from a large birth cohort in Japan, which included 104 062 fetuses, were analyzed. The primary outcome was the development of leukemia or brain tumors diagnosed by community physicians during the first 3 years after birth. Exposure factors were medical agents, including anticancer agents, ionizing radiation, and anesthetics, handled by mothers during pregnancy or by fathers for 3 months before conception. The incidence of leukemia, but not of brain tumors, was higher in mothers exposed to anticancer drugs. Multivariable regression analysis showed that maternal exposure to anticancer drugs was associated with an increased risk of leukemia in offspring older than 1 year (adjusted relative risk, 7.99 [95% confidence interval, 1.98-32.3]). Detailed information obtained from medical certificates of patients with identified leukemia revealed no infant leukemia but acute lymphoblastic leukemias in the exposed group. Our findings suggest that maternal occupational exposure to anticancer drugs may be a potential risk factor for acute lymphoblastic leukemia in offspring older than 1 year. Effective prevention methods may be necessary to prevent maternal exposure to anticancer drugs and to reduce the risk of childhood malignant neoplasms.

Metabolic capacity to alter polycyclic aromatic hydrocarbons and its microbe-mediated remediation

The elimination of contaminants caused by anthropogenic activities and rapid industrialization can be accomplished using the widely used technology of bioremediation. Recent years have seen significant advancement in our understanding of the bioremediation of coupled polycyclic aromatic hydrocarbon contamination caused by microbial communities including bacteria, algae, fungi, yeast, etc. One of the newest techniques is microbial-based bioremediation because of its greater productivity, high efficiency, and non-toxic approach. Microbes are appealing candidates for bioremediation because they have amazing metabolic capacity to alter most types of organic material and can endure harsh environmental conditions. Microbes have been characterized as extremophiles that can survive in a variety of environmental circumstances, making them the treasure troves for environmental cleanup and the recovery of contaminated soil. In this study, the mechanisms underlying the bioremediation process as well as the current situation of microbial bioremediation of polycyclic aromatic hydrocarbon are briefly described.

Toxic metals in human milk in relation to tobacco smoke exposure

Several reports confirm the deleterious effects of tobacco smoking and exposure to second-hand smoke (SHS) resulting in changes in the composition of breast milk. The aim of our study was to compare the levels of selected essential, as well as, toxic metals found in colostrum (collected at day 1 ± 2 post-birth) and mature milk (1 month ± 7 days post-birth) of nonsmoking women (n = 52) compared to those found in women who smoke tobacco (n = 51) and women exposed to second-hand smoke during pregnancy and lactation (n = 47). Women's non-smoking or smoking status was determined by their responses to a questionnaire, including questions about others who may smoke in the home environment, and confirmed by measurement of cotinine in the blood serum by high performance liquid chromatography with diode array detector (HPLC-DAD). Inductively coupled plasma mass spectrometry (ICP-MS) and flame atomic absorption spectroscopy (F-AAS) techniques were used to determine the metal concentrations in colostrum and mature milk previously digested by a microwave mineralizer. We confirmed that exposure to tobacco smoke increases concentrations of heavy metals (cadmium and lead) in colostrum and mature milk. These increased concentrations of heavy metals may disturb the action of bioactive substances necessary for the optimal growth and development of newborns and infants. These findings support the need for increased concern and information to lactating women about preventing their exposure to cigarette smoking and SHS due to the adverse effects of tobacco smoke on breast milk with added risks to their infants.

Biases Inherent in Studies of Coffee Consumption in Early Pregnancy and the Risks of Subsequent Events

Consumption of coffee by women early in their pregnancy has been viewed as potentially increasing the risk of miscarriage, low birth weight, and childhood leukemias. Many of these reports of epidemiologic studies have not acknowledged the potential biases inherent in studying the relationship between early-pregnancy-coffee consumption and subsequent events. I discuss five of these biases, recall bias, misclassification, residual confounding, reverse causation, and publication bias. Each might account for claims that attribute adversities to early-pregnancy-coffee consumption. To what extent these biases can be avoided remains to be determined. As a minimum, these biases need to be acknowledged wherever they might account for what is reported.

Maternal Exposure to Pesticides, Paternal Occupation in the Army/Police Force, and CYP2D6*4 Polymorphism in the Etiology of Childhood Acute Leukemia

Epidemiologic studies have suggested that parental occupations, pesticide use, environmental factors, and genetic polymorphism are involved in the etiology of childhood acute leukemia (CAL). In total, 116 cases of CAL and 162 controls were recruited and submitted to blood drawing to assess the presence of genetic polymorphisms. Parental occupations, pesticides exposure, and other potential determinants were investigated. Increased risk for CAL was associated with prenatal maternal use of insecticides/rodenticides (odds ratio [OR]=1.87; 95% confidence intervals [CI], 1.04-3.33), with subjects living <100 m from pesticide-treated fields (OR=3.21; 95% CI, 1.37-7.53) and with a paternal occupation as traffic warden/policeman (OR=4.02; 95% CI, 1.63-9.87). Associations were found between CAL and genetic polymorphism of CYP2D6*4 for homozygous alleles (mutant type/mutant type: OR=6.39; 95% CI, 1.17-34.66). In conclusion, despite the small sample size, maternal prenatal exposure to pesticides, paternal occupation as a traffic warden/police officer, and CYP2D6*4 polymorphism could play a role in the etiology of CAL.

EPHX1 rs1051740 T>C (Tyr113His) is strongly associated with acute myeloid leukemia and KMT2A rearrangements in early age

Experimental and epidemiological data have shown that acute myeloid leukemia in early-age (i-AML) originates prenatally. The risk association between transplacental exposure to benzene metabolites and i-AML might be influenced by genetic susceptibility. In this study, we investigated the relationship between genetic polymorphisms in CYP2E1, EPHX1, MPO, NQO1, GSTM1 and GSTT1 genes, and i-AML risk. The study included 101 i-AMLs and 416 healthy controls. Genomic DNA from study subjects was purified from bone marrow or peripheral blood aspirates and genotyped for genetic polymorphisms by real-time PCR allelic discrimination, Sanger sequencing and multiplex PCR. Crude and adjusted odds ratios (OR, _adjOR, respectively) with 95% confidence intervals (95% CI) were assessed using unconditional logistic regression to estimate the magnitude of risk associations. EPHX1 rs1051740 T>C was associated with i-AML risk under the co-dominant (_adjOR 3.04, P = 0.003) and recessive (_adjOR 2.99, P = 0.002) models. In stratified analysis, EPHX1 rs1051740 was associated with increased risk for i-AML with KMT2A rearrangement (_adjOR 3.06, P = 0.045), i-AML with megakaryocytic differentiation (_adjOR 5.10, P = 0.008), and i-AML with type I mutation (_adjOR 2.02, P = 0.037). EPHX1 rs1051740-rs2234922 C-G haplotype was also associated with increased risk for i-AML (_adjOR 2.55, P = 0.043), and for i-AML with KMT2A rearrangement (_adjOR 3.23, P = 0.034). Since EPHX1 enzyme is essential in cellular defense against epoxides, the diminished enzymatic activity conferred by the variant allele C could explain the risk associations found for i-AML. In conclusion, EPHX1 rs1051740 plays an important role in i-AML's genetic susceptibility by modulating the carcinogenic effects of epoxide exposures in the bone marrow.

An overview of disparities in childhood cancer: Report on the Inaugural Symposium on Childhood Cancer Health Disparities, Houston, Texas, 2016

The Inaugural Symposium on Childhood Cancer Health Disparities was held in Houston, Texas, on November 2, 2016. The symposium was attended by 109 scientists and clinicians from diverse disciplinary backgrounds with interests in pediatric cancer disparities and focused on reviewing our current knowledge of disparities in cancer risk and outcomes for select childhood cancers. Following a full day of topical sessions, everyone participated in a brainstorming session to develop a working strategy for the continued expansion of research in this area. This meeting was designed to serve as a springboard for examination of childhood cancer disparities from a more unified and systematic approach and to enhance awareness of this area of need.

Early-age Acute Leukemia: Revisiting Two Decades of the Brazilian Collaborative Study Group

The understanding of leukemogenesis in early-age acute leukemia (EAL) has improved remarkably. Initiating somatic mutations detected in dried neonatal blood spots (DNBS) and in cord blood samples of affected children with leukemia have been proven to be acquired prenatally. However, to date, few epidemiological studies have been carried out exploring EAL that include infants and children 13-24 months of age at the diagnosis. Maternal exposure to transplacental DNA-damaging substances during pregnancy has been suggested to be a risk factor for EAL. Most cases of infants with acute lymphoblastic (i-ALL) or myeloid leukemia (i-AML) have KMT2A gene rearrangements (KMT2A-r), which disturb its essential role as an epigenetic regulator of hematopoiesis. Due to the short latency period for EAL and the fact that KMT2A-r resembles those found in secondary AML, exposure to topoisomerase II inhibitors has been associated with transplacental risk as proxi for causality. EAL studies have been conducted in Brazil for over two decades, combining observational epidemiology, leukemia biology, and clinical data. EAL was investigated considering (i) age strata (infants vs. 13-24 months-old); (ii) somatic mutations associated with i-ALL and i-AML; (iii) ethnic-geographic variations; (iv) contribution of maternal genotypes; and (v) time latency of exposures and mutations in DNBS. Interactions of acquired and constitutive gene mutations are challenging tools to test risk factor associations for EAL. In this review we summarize the EAL scenario (including B-cell precursor-ALL, T-ALL, and AML) results combining environmental and genetic susceptibility risk factors and we raise questions that should be considered for further action.

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.

Childhood Leukemia: A Preventable Disease

In contrast to most pediatric cancers, there is a growing body of literature, nationally and internationally, that has implicated the role of several environmental indoor and outdoor hazards in the etiology of childhood leukemia. For example, exposures to solvents, traffic, pesticides, and tobacco smoke have consistently demonstrated positive associations with the risk of developing childhood leukemia. Intake of vitamins and folate supplementation during the preconception period or pregnancy has been demonstrated to have a protective effect. Despite the strength of these findings, the dissemination of this knowledge to clinicians has been limited. Some children may be more vulnerable than others as documented by the high and increasing incidence of childhood leukemia in Hispanics. To protect children's health, it is prudent to establish programs to alter exposure to those factors with well-established associations with leukemia risk rather than to suspend judgment until no uncertainty remains. This is particularly true because other serious health outcomes (both negative and positive) have been associated with the same exposures. We draw from historical examples to put in perspective the arguments of association versus causation, as well as to discuss benefits versus risks of immediate and long-term preventive actions.

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.

Protocol for study of financial incentives for smoking cessation in pregnancy (FISCP): randomised, multicentre study

INTRODUCTION

Maternal smoking during pregnancy is associated with adverse perinatal and postnatal health outcomes. The efficacy of nicotine replacement therapies in helping pregnant smokers to quit is not clearly demonstrated; therefore new interventions should be proposed and assessed. Financial incentives rewarding abstinence from tobacco smoking is one of the promising options.

OBJECTIVE

To assess the efficacy of financial incentives on smoking abstinence among French pregnant smokers.

PARTICIPANTS

pregnant smokers aged ≥18 years, smoking at least five manufactured or three roll-your-own cigarettes per day, and pregnant for <18 weeks of amenorrhoea (WA).

SETTING

participants will be recruited, included and followed-up at monthly face-to-face visits in 16 maternity wards in France.

INTERVENTIONS

participants will be randomised to a control or an intervention group. After a predefined quit date, participants in the control group will receive €20 vouchers at the completion of each visit but no financial incentive for smoking abstinence. Participants in the intervention group will be rewarded for their abstinence by vouchers on top of the €20 show-up fee. The amount of reward for abstinence will increase as a function of duration of abstinence to stimulate longer periods of abstinence.

MAIN OUTCOME MEASURE

complete abstinence from quit date to the last predelivery visit.

SECONDARY OUTCOME MEASURES

point prevalence abstinence, time to relapse to smoking, birth weight, fetal growth restriction, preterm birth. Main data analysis: outcomes will be analysed on an intention-to-treat (ITT) basis. The ITT population is defined as all randomised smoking pregnant women.

ETHICS AND DISSEMINATION

The research protocol was approved by the ethics committee (Comité de Protection des Personnes, CPP) of the Pitié-Salpêtrière Hospital on 15 May 2015, and Amendment No 1 was approved on 13 July 2015. Results will be presented at scientific meetings and published.

TRIAL REGISTRATION NUMBER

NCT02606227; Pre-results.

Socioeconomic Status and Childhood Leukemia Incidence in Switzerland

Socioeconomic status (SES) discrepancies exist for child and adult cancer morbidity and are a major public health concern. In this Swiss population-based matched case–control study on the etiology of childhood leukemia, we selected the cases from the Swiss Childhood Cancer Registry diagnosed since 1991 and the controls randomly from census. We assigned eight controls per case from the 1990 and 2000 census and matched them by the year of birth and gender. SES information for both cases and controls was obtained from census records by probabilistic record linkage. We investigated the association of SES with childhood leukemia in Switzerland, and explored whether it varied with different definitions of socioeconomic status (parental education, living condition, area-based SES), time period, and age. In conditional logistic regression analyses of 565 leukemia cases and 4433 controls, we found no consistent evidence for an association between SES and childhood leukemia. The odds ratio comparing the highest with the lowest SES category ranged from 0.95 (95% CI: 0.71–1.26; P_trend = 0.73) for paternal education to 1.37 (1.00–1.89; P_trend = 0.064) for maternal education. No effect modification was found for time period and age at diagnosis. Based on this population-based study, which avoided participation and reporting bias, we assume the potential association of socioeconomic status and childhood leukemia if existing to be small. This study did not find evidence that socioeconomic status, of Switzerland or comparable countries, is a relevant risk factor or strong confounder in etiological investigations on childhood leukemia.

Maternal Alcohol Consumption during Pregnancy and Early Age Leukemia Risk in Brazil

Objectives. To investigate the association between the maternal alcohol consumption during pregnancy and early age leukemia (EAL) in offspring. Methods. Datasets were analyzed from a case-control study carried out in Brazil during 1999-2007. Data were obtained by maternal interviews using a standardized questionnaire. The present study included 675 children (193 acute lymphoid leukemia (ALL), 59 acute myeloid leukemia (AML), and 423 controls). Unconditional logistic regression was performed, and adjusted odds ratios (adj. OR) on the association between alcohol consumption and EAL were ascertained. Results. Alcohol consumption was reported by 43% of ALL and 39% of AML case mothers and 35.5% of controls'. Beer consumption before and during pregnancy was associated with ALL in crude analysis (OR = 1.54, 95% CI, 1.08-2.19), although in adjusted analysis no statistical significance was found. For weekly intake of ≤1 glass (adj. OR = 1.30, 95% CI, 0.71-2.36) and ≥1 glass/week (adj. OR = 1.47, 95% CI, 0.88-2.46) a potential dose-response was observed (P trend < 0.03). Conclusion. This study failed to support the hypothesis of an increased risk of EAL associated with maternal alcohol intake during pregnancy, neither with the interaction with tobacco nor with alcohol consumption.

Maternal benzene exposure during pregnancy and risk of childhood acute lymphoblastic leukemia: a meta-analysis of epidemiologic studies

Background

The prevalence of childhood leukemia is increasing rapidly all over the world. However, studies on maternal benzene exposure during pregnancy and childhood acute lymphoblastic leukemia (ALL) have not been systematically assessed. Therefore, we performed a meta-analysis to investigate the association between maternal solvent, paint, petroleum exposure, and smoking during pregnancy and risk of childhood ALL.

Methods

Relevant studies up to September 1^st, 2013 were identified by searching the PubMed, EMBASE, Cochrane library and the Web of Science databases. The effects were pooled using either fixed or random effect models based on the heterogeneity of the studies.

Results

Twenty-eight case-control studies and one cohort study were included for analysis, with a total of 16,695 cases and 1,472,786 controls involved. Pooled odds ratio (OR) with 95% confidence interval (CI) for ALL was 1.25 (1.09, 1.45) for solvent, 1.23 (1.02, 1.47) for paint, 1.42 (1.10, 1.84) for petroleum exposure, and 0.99 (0.93, 1.06) for maternal smoking during pregnancy. No publication bias was found in this meta-analysis and consistent results were observed for subgroup and sensitivity analyses.

Conclusions

Childhood ALL was associated with maternal solvent, paint, and petroleum exposure during pregnancy. No association was found between ALL and maternal smoking during pregnancy. Avoidance of maternal occupational and environmental benzene exposure during pregnancy could contribute to a decrease in the risk of childhood ALL.

RAS mutations in early age leukaemia modulated by NQO1 rs1800566 (C609T) are associated with second-hand smoking exposures

BACKGROUND

Deregulation of the MAPK genes signalling caused by somatic mutations have been implied in leukaemia pathogenesis, including RAS mutation (RASmut) in acute myeloid leukaemia (AML), which has been associated with intra-uterine chemical exposures. A case-case study was conducted in order to explore maternal and child exposures to tobacco smoking associations with early age leukaemia (EAL).

METHODS

Covariables of reference were MLL rearrangements (MLL-r), RASmut and NQO1 rs1800566 (C609T). Samples from 150 acute lymphoblastic leukaemia (ALL) and 85 AML were included. Maternal exposures were assessed using a structured questionnaire with demographic, personal habits and residence history information. Restriction fragment length polymorphism and denaturing high performance liquid chromatography were used to screen FLT3, KRAS, and NRAS mutations; direct sequencing was performed to validate the results. NQO1 polymorphism was detected by real-time allelic discrimination technique.

RESULTS

Overall, RASmut were detected in 28.7% of EAL cases; BRAFmut was found only in one AML patient. Higher rate of KRASmut was found in ALL (30.3%) compared to AML (20.8%) with MLL-r; RASmut showed an association with second-hand tobacco smoking exposures (OR, 3.06, 95% CI, 1.03-9.07). A considerable increased risk for EAL with the combination of RASmut and NQO1 609CT (OR, 4.24, 95% CI, 1.24-14.50) was observed.

CONCLUSIONS

Our data demonstrated the increased risk association between maternal smoking and EAL with MLL-r. Additionally, suggests that children second-hand tobacco exposures are associated with increased risk of EAL with RASmut modulated by NQO1 rs1800566 (C609T).