A multinational case-control study on childhood brain tumours, anthropogenic factors, birth characteristics and prenatal exposures: A validation of interview data

Maternal smoking, consumption of alcohol, and caffeinated beverages during pregnancy and the risk of childhood brain tumors: a meta-analysis of observational studies

BACKGROUND

We conducted this meta-analysis to investigate the potential association between maternal smoking, alcohol and caffeinated beverages consumption during pregnancy and the risk of childhood brain tumors (CBTs).

METHODS

A thorough search was carried out on PubMed, Embase, Web of Science, Cochrane Library, and China National Knowledge Internet to identify pertinent articles. Fixed or random effects model was applied to meta-analyze the data.

RESULTS

The results suggested a borderline statistically significant increased risk of CBTs associated with maternal smoking during pregnancy (OR 1.04, 95% CI 0.99-1.09). We found that passive smoking (OR 1.12, 95% CI 1.03-1.20), rather than active smoking (OR 1.00, 95% CI 0.93-1.07), led to an increased risk of CBTs. The results suggested a higher risk in 0-1 year old children (OR 1.21, 95% CI 0.94-1.56), followed by 0-4 years old children (OR 1.12, 95% CI 0.97-1.28) and 5-9 years old children (OR 1.11, 95% CI 0.95-1.29). This meta-analysis found no significant association between maternal alcohol consumption during pregnancy and CBTs risk (OR 1.00, 95% CI 0.80-1.24). An increased risk of CBTs was found to be associated with maternal consumption of caffeinated beverages (OR 1.16, 95% CI 1.07-1.26) during pregnancy, especially coffee (OR 1.18, 95% CI 1.00-1.38).

CONCLUSIONS

Maternal passive smoking, consumption of caffeinated beverages during pregnancy should be considered as risk factors for CBTs, especially glioma. More prospective cohort studies are warranted to provide a higher level of evidence.

Risk factors for childhood brain tumours: A systematic review and meta-analysis of observational studies from 1976 to 2022

BACKGROUND

Childhood brain tumours (CBTs) are the leading cause of cancer death in children under the age of 20 years globally. Though the aetiology of CBT remains poorly understood, it is thought to be multifactorial. We aimed to synthesize potential risk factors for CBT to inform primary prevention.

METHODS

We conducted a systematic review and meta-analysis of epidemiological studies indexed in the PubMed, Web of Science, and Embase databases from the start of those resources through 27 July 2023. We included data from case-control or cohort studies that reported effect estimates for each risk factor around the time of conception, during pregnancy and/or during post-natal period. Random effects meta-analysis was used to estimate summary effect sizes (ES) and 95% confidence intervals (CIs). We also quantified heterogeneity (I2) across studies.

FINDINGS

A total of 4040 studies were identified, of which 181 studies (85 case-control and 96 cohort studies) met our criteria for inclusion. Of all eligible studies, 50% (n = 91) were conducted in Europe, 32% (n = 57) in North America, 9% (n = 16) in Australia, 8% (n = 15) in Asia, 1% (n = 2) in South America, and none in Africa. We found associations for some modifiable risk factors including childhood domestic exposures to insecticides (ES 1.44, 95% CI 1.20-1.73) and herbicides (ES 2.38, 95% CI 1.31-4.33). Maternal domestic exposure to insecticides (ES 1.45, 95% CI 1.09-1.94), maternal consumption of cured meat (ES 1.51, 95% CI 1.05-2.17) and coffee ≥ 2 cups/day (ES 1.45, 95% 95% CI 1.07-1.95) during pregnancy, and maternal exposure to benzene (ES 2.22; 95% CI 1.01-4.88) before conception were associated with CBTs in case-control studies. Also, paternal occupational exposure to pesticides (ES 1.48, 95% CI 1.23-1.77) and benzene (ES 1.74, 95% CI 1.10-2.76) before conception and during pregnancy were associated in case-control studies and in combined analysis. On the other hand, assisted reproductive technology (ART) (ES 1.32, 95% CI 1.05-1.67), caesarean section (CS) (ES 1.12, 95% CI 1.01-1.25), paternal occupational exposure to paint before conception (ES 1.56, 95% CI 1.02-2.40) and maternal smoking > 10 cigarettes per day during pregnancy (ES 1.18, 95% CI 1.00-1.40) were associated with CBT in cohort studies. Maternal intake of vitamins and folic acid during pregnancy was inversely associated in cohort studies. Hormonal/infertility treatment, breastfeeding, child day-care attendance, maternal exposure to electric heated waterbed, tea and alcohol consumption during pregnancy were among those not associated with CBT in both case-control and cohort studies.

CONCLUSION

Our results should be interpreted with caution, especially as most associations between risk factors and CBT were discordant between cohort and case-control studies. At present, it is premature for any CBT to define specific primary prevention guidelines.

Maternal and Perinatal Factors Associated With Childhood Brain Tumors: A Case-Control Study in Vietnam

INTRODUCTION

Brain cancer is the leading cause of cancer-related deaths in children and the majority of childhood brain tumors are diagnosed without determination of their underlying etiology. Little is known about risk factors for childhood brain tumors in Vietnam. The objective of this case-control study was to identify maternal and perinatal factors associated with brain tumors occurring in young Vietnamese children and adolescents.

METHODS

We conducted a hospital-based case-control study at Viet Duc University Hospital in Hanoi, Vietnam. Cases consisted of children with brain tumors aged 0-14 years old admitted to the hospital from January 2020 to July 2022 while the controls were age and sex-matched hospitalized children diagnosed with head trauma. Perinatal characteristics were abstracted from hospital medical records and maternal medical, behavioral, and sociodemographic factors were collected through in-person interviews. Conditional logistic regression models were used to examine maternal and perinatal factors associated with childhood brain tumors.

RESULTS

The study sample included 220 children (110 cases and 110 controls) whose average age was 8.9 years and 41.8% were girls. Children born to mothers aged greater than 30 years at the time of the child's birth had a higher risk of childhood brain tumors compared to those born to mothers aged from 18 to 30 years old (OR = 2.55; 95% CI: 1.13-5.75). Additionally low maternal body mass index prior to the current pregnancy of <18.5 kg/m2 significantly increased the odds of having a child with a brain tumor in relation to normal maternal body mass index from 18.5-22.9 kg/m2 (OR = 3.19; 95% CI: 1.36 - 7.50).

CONCLUSION

Advanced maternal age and being markedly underweight were associated with an increased odds of having a child with a brain tumor. A population-based study with larger sample size is needed to confirm and extend the present findings.

Survival and long-term socioeconomic consequences of childhood and adolescent onset of brain tumours

AIM

To evaluate survival distributions, long-term socioeconomic consequences, and health care costs in patients with childhood and adolescent onset of brain tumours in a Danish nationwide prospective cohort study.

METHOD

A search of national registries identified 2283 patients (1198 males, 1085 females; mean age 9 years 6 months [SD 5 years 7 months]) diagnosed with a brain tumour between 1980 and 2015 and aged no older than 18 years at diagnosis. These were compared with sex-, age-, and residency-matched comparison individuals. Patients with malignant tumours were compared with those with benign tumours. Survival distributions were estimated by the Kaplan-Meier method and hazard ratio by the Cox proportional hazard model. Socioeconomic data at age 20 and 30 years were assessed.

RESULTS

The probability of mortality was highest during the first year after tumour diagnosis. In young adulthood, the patients were generally less likely to be married, had lower grade-point averages, educational levels, and income, were less likely to be in employment, and had higher health care costs than comparison individuals. Patients with malignant tumours had worse outcomes with respect to education, employment, and health care costs than those with benign tumours.

INTERPRETATION

A diagnosis of brain tumour in childhood and adolescence adversely affects survival and has negative long-term socioeconomic consequences, especially in patients with malignant tumours. These patients require continuous social support.

Maternal diabetes and childhood cancer risks in offspring: two population-based studies

BACKGROUND

The effect of maternal diabetes on childhood cancer has not been widely studied.

METHODS

We examined this in two population-based studies in Denmark (N = 6420 cancer cases, 160,484 controls) and Taiwan (N = 2160 cancer cases, 2,076,877 non-cases) using logistic regression and Cox proportional hazard regression adjusted for birth year, child's sex, maternal age and birth order.

RESULTS

Gestational diabetes in Denmark [odds ratio (OR) = 0.98, 95% confidence interval (CI): 0.71-1.35] or type II and gestational diabetes in Taiwan (type II: hazard ratio (HR) = 0.81, 95% CI: 0.63-1.05; gestational diabetes: HR = 1.06, 95% CI: 0.92-1.22) were not associated with cancer (all types combined). In Denmark, maternal type I diabetes was associated with the risk of glioma (OR = 2.33, 95% CI: 1.04-5.22), while in Taiwan, the risks of glioma (HR = 1.59, 95% CI: 1.01-2.50) were elevated among children whose mothers had gestational diabetes. There was a twofold increased risk for hepatoblastoma with maternal type II diabetes (HR = 2.02, 95% CI: 1.02-4.00).

CONCLUSIONS

Our results suggest that maternal diabetes is an important risk factor for certain types of childhood cancers, emphasising the need for effective interventions targeting maternal diabetes to prevent serious health effects in offspring.

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

Background

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

Methods

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

Results

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

Conclusions

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

The risk of childhood brain tumors associated with delivery interventions: A Danish matched case-control study

BACKGROUND

Head trauma has been associated with increased brain tumor risk in adults. Instrument assisted delivery can be a cause of head trauma in newborns. The goal of this study was to determine if instrument-assisted deliveries influenced the odds of childhood brain tumors in Denmark.

METHODS

We conducted a matched case-control study of childhood (<20 years) brain tumors in Denmark born between 1978 and 2013 and diagnosed 1978-2016. A total of 1678 brain tumor cases were identified and 25 controls were matched to each case based on the child's sex and birth date (N = 40,934). Conditional logistic regression was used to estimate effects (odds ratios (OR) and 95% confidence intervals (95%CI)) for variables of interest.

RESULTS

Compared to children birthed by spontaneous vaginal delivery, children who later developed ependymomas (N = 118) had a greater likelihood of having experienced vacuum assisted deliveries (OR=1.74, 95% CI 1.02-2.96). Forceps use was low, and declined across the study period. We did not observe an overall increase in all CNS tumors (combined) with either vacuum delivery (OR=0.99, 95% CI 0.84-1.18) or forceps delivery (OR=1.26, 95% CI 0.78-2.03).

CONCLUSION

Our findings suggest an association between vacuum assisted deliveries and ependymomas.

Maternal and perinatal factors are associated with risk of pediatric central nervous system tumors and poorer survival after diagnosis

Central nervous system (CNS) tumors are the most common solid tumors in children. Findings on the role of maternal and perinatal factors on the susceptibility or outcome of these tumors are inconclusive. Therefore, we investigated the association between these early-life factors, risk, and survival of pediatric CNS tumors, using data from one of the world’s largest and most diverse cancer registries. Information on pediatric CNS tumor cases (n = 1950) for the period 1995–2011 was obtained from the Texas Cancer Registry. Birth certificate controls were frequency-matched on birth year at a ratio of 10:1 for the same period. Evaluated maternal and perinatal variables were obtained from birth records. Unconditional logistic regression was used to generate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for etiological factors. Additionally, Cox proportional hazards regression was employed to assess adjusted hazard ratios (HRs) and 95% CIs for survival factors. The results indicated that Hispanic and non-Hispanic black mothers were less likely to have children with CNS tumors compared to non-Hispanic white mothers (OR 0.88 [95% CI 0.78–0.98] P-value = 0.019; OR 0.79 [95% CI 0.67–0.93 P-value = 0.004], respectively). Infants born large for gestational age (OR 1.26 [95% CI 1.07–1.47] P-value = 0.004) and those delivered pre-term (OR 1.19 [95% CI 1.04–1.38] P-value = 0.013) showed an increased risk of CNS tumors. Infants born by vaginal forceps or vacuum delivery had a higher risk of CNS tumors compared to those born by spontaneous vaginal delivery (OR 1.35 [95% CI 1.12–1.62] P-value = 0.002). Additionally, offspring of Hispanic and non-Hispanic black mothers showed a higher risk of death (HR 1.45 [95% CI 1.16–1.80] P-value = 0.001; HR 1.53 [95% CI 1.12–2.09] P-value = 0.008, respectively). Infants born by cesarean had a higher risk of death compared to those delivered vaginally (HR 1.28 [95% CI 1.05–1.57] P-value = 0.016). These findings indicate the important role of maternal and perinatal characteristics in the etiology and survival of these clinically significant malignancies.

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Sex-specific effects of in utero and adult tobacco smoke exposure

Tobacco smoke has harmful effects on a multiorgan level. Exposure to smoke, whether in utero or environmental, significantly increases susceptibility. This susceptibility has been identified to be divergent between males and females. However, there remains a distinct lack of thorough research into the relationship between sex and exposure to tobacco. Females tend to generate a more significant response than males during adulthood exposure. The intrauterine environment is meticulously controlled, and exposure to tobacco presents a significant factor that contributes to poor health outcomes and susceptibility later in life. Analysis of these effects in relation to the sex of the offspring is yet to be holistically reviewed and summarized. In this review, we will delineate the time-dependent relationship between tobacco smoke exposure and sex-specific disease susceptibility. We further outline possible biological mechanisms that may contribute to the identified pattern.

Perinatal and early life risk factors for childhood brain tumors: Is instrument-assisted delivery associated with higher risk?

BACKGROUND

The childhood peak of brain tumors suggests that early-life exposures might have a role in their etiology. Hence, we examined in the Greek National Registry for Childhood Hematological Malignancies and Solid tumors (NARECHEM-ST) whether perinatal and early-life risk factors influence the risk of childhood brain tumors.

METHODS

In a nationwide case-control study, we included 203 cases (0-14 years) with a diagnosis of brain tumor in NARECHEM-ST (2010-2016) and 406 age-, sex-, and center-matched hospital controls. Information was collected via interviews with the guardians and we analyzed the variables of interest in multivariable conditional logistic regression models.

RESULTS

Instrument-assisted delivery was associated with higher (OR: 7.82, 95%CI: 2.18-28.03), whereas caesarean delivery with lower (OR: 0.67, 95%CI: 0.45-0.99) risk of childhood brain tumors, as compared to spontaneous vaginal delivery. Maternal alcohol consumption during pregnancy (OR: 2.35, 95%CI: 1.45-3.81) and history of living in a farm (OR: 4.98, 2.40-10.32) increased the odds of childhood brain tumors. Conversely, higher birth order was associated with lower risk (OR for 2nd vs. 1st child: 0.60, 95%CI: 0.40-0.89 and OR for 3^rd vs. 1^st: 0.34, 95%CI: 0.18-0.63). Birth weight, gestational age, parental age, history of infertility, smoking during pregnancy, allergic diseases, and maternal diseases during pregnancy showed no significant associations.

CONCLUSIONS

Perinatal and early-life risk factors, and specifically indicators of brain trauma, exposure to toxic agents and immune system maturation, might be involved in the pathogenesis of childhood brain tumors. Larger studies should aim to replicate our findings and examine associations with tumor subtypes.

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

Introduction

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

Methods

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

Results

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

Conclusions

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

The association between birth order and childhood brain tumors: a systematic review and meta-analysis

The incidence of childhood brain tumors (CBT) has increased worldwide, likely resulting from the improvements of early diagnostics. We conducted a systematic review and meta-analysis to clarify the association between birth order and CBT. We followed established guidelines to systematically search Ovid Medline, PubMed, and the Cochrane Library for English language studies, published before March 2018. Quality assessment was performed using the Newcastle-Ottawa Scale. Meta-analysis provided pooled risk estimates and their 95% confidence intervals (CIs) for birth order and CBT. We identified 16 case-control studies with a total sample of 32 439 cases and 166 144 controls and three prospective cohort studies (i.e. 4515 incident cases of CBTs among 5 281 558 participants). Compared with first birth order, the meta-odds ratio for second birth order in case-control studies was 1.04 (95% CI: 1.01-1.07), that for third birth order was 0.98 (95% CI: 0.90-1.06), and that for fourth order was 0.85 (95% CI: 0.78-0.92). The meta-hazard ratio for second or higher birth order compared with first birth order in cohort studies was 1.00 (95% CI: 0.96-1.05). We found no association between birth order and CBT in both case-control and cohort study designs; the small association observed for fourth birth order deserves further consideration.

Residential exposure to pesticides as risk factor for childhood and young adult brain tumors: A systematic review and meta-analysis

BACKGROUND

Accumulating evidence suggests a positive association between exposure to non-agricultural pesticides and childhood brain tumors (CBT).

OBJECTIVE

(1) To conduct a systematic review and meta-analysis of published studies on the association between residential/household/domestic exposure to pesticides and childhood brain tumors. (2) To clarify variables that could impact the results.

METHODS

Publications in English were identified from a MEDLINE search through 28 February 2017 and from the reference list of identified publications. Risk estimates were extracted from 18 case-control studies published between 1979 and 2016 and study quality assessments were performed. Summary odds ratios (mOR) were calculated according to fixed and random-effect meta-analysis models. Separate analyses were conducted after stratification for study quality, critical exposure period, exposure location, specific exposures, pesticide category, application methods, type of pest treated, type of CBT, child's age at diagnosis and geographic location.

RESULTS

Statistically significant associations were observed with CBT after combining all studies (mOR: 1.26; 95% CI: 1.13-1.40) without evidence of inconsistency between study results or publication bias. Specifically, increased risks were observed for several groupings and more particularly for gliomas and exposure involving insecticides. Statistical significance was also reached for high quality studies, for all exposure periods, for indoor exposure and, more particularly, during the prenatal period for all stratifications involving insecticides (except for outdoor use), for pet treatments, for flea/tick treatment, for studies from USA/Canada and studies from Europe (borderline) as well as for data from studies including children of up to 10years at diagnosis and of up to 15years.

CONCLUSIONS

Our findings support an association between residential exposure to pesticides and childhood brain tumors. Although causality cannot be established, these results add to the evidence leading to recommend limiting residential use of pesticides and to support public health policies serving this objective.

Parental smoking, maternal alcohol, coffee and tea consumption and the risk of childhood brain tumours: the ESTELLE and ESCALE studies (SFCE, France)

PURPOSE

To investigate whether parental smoking around the time of pregnancy or maternal consumption of beverages (alcohol, coffee, or tea) during pregnancy were associated with the risk of CBT.

METHODS

We pooled data from two French national population-based case-control studies with similar designs conducted in 2003-2004 and 2010-2011. The mothers of 510 CBT cases (directly recruited from the national childhood cancer register) and 3,102 controls aged under 15 years, frequency matched by age and gender, were interviewed through telephone, which included questions about prenatal parental smoking and maternal consumption of alcohol, coffee and tea. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression, adjusted for age, sex and study of origin.

RESULTS

No association was seen between CBT and the mother smoking or drinking alcohol, coffee, or tea during the index pregnancy. The OR between CBT and paternal smoking in the year before birth (as reported by the mother) was 1.25 (95% CI 1.03, 1.52) with an OR of 1.09 (0.99, 1.19) for every 10 cigarettes per day (CPD) smoked. The association between paternal smoking and CBT appeared to be stronger in children diagnosed before the age of five years (OR 1.52, 95% CI 1.14, 2.02) and for astrocytoma (OR 1.86, 95% CI 1.26, 2.74).

CONCLUSION

We found some evidence of a weak association between paternal smoking in the year before the child's birth and CBT, especially astrocytomas. These findings need to be replicated in other samples, using similar classifications of tumour subtypes.

Birth weight and subsequent risk of childhood primary brain tumors: An updated meta-analysis

BACKGROUND

Primary brain tumors are common in childhood, but the etiology is largely unclear. As studies on birth weight as a risk factor for the occurrence of histologically specified tumors have been inconclusive, we decided to update a 2008 meta-analysis on the subject.

METHODS

A search strategy was performed in Medline and EMBASE for the period 2007-2016. We included six new studies and performed further subgroup analyses for medulloblastoma and primitive neuroectodermal tumors (PNETs). Dichotomous analyses were performed for low (2,500 g) and high birth weight (4,000 g cutoff point).

RESULTS

Our results confirmed that high birth weight increases the risk of astrocytoma (odds ratio [OR] = 1.60, 95% confidence interval [CI]: 1.23-2.09) and medulloblastoma/PNET. However, subgroup analysis revealed an increased risk of medulloblastoma (OR = 1.31, 95% CI: 1.08-1.58) but not of PNET (OR = 1.16, 95% CI: 0.92-1.46). Low birth weight was associated with an increased risk of medulloblastoma/PNET. Subgroup analysis for medulloblastoma and PNET revealed increased risk but CIs included zero. Neither low nor high birth weight was associated with the risk of ependymoma.

CONCLUSIONS

While an association between high birth weight and astrocytoma was confirmed, more studies are needed to investigate medulloblastoma and PNET risk in children with high and low birth weight.

Microwaves and Alzheimer's disease

Alzheimer's diseases (AD) is the most common type of dementia and a neurodegenerative disease that occurs when the nerve cells in the brain die. The cause and treatment of AD remain unknown. However, AD is a disease that affects the brain, an organ that controls behavior. Accordingly, anything that can interact with the brain may affect this organ positively or negatively, thereby protecting or encouraging AD. In this regard, modern life encompasses microwaves for all issues including industrial, communications, medical and domestic tenders, and among all applications, the cell phone wave, which directly exposes the brain, continues to be the most used. Evidence suggests that microwaves may produce various biological effects on the central nervous system (CNS) and many arguments relay the possibility that microwaves may be involved in the pathophysiology of CNS disease, including AD. By contrast, previous studies have reported some beneficial cognitive effects and that microwaves may protect against cognitive impairment in AD. However, although many of the beneficial effects of microwaves are derived from animal models, but can easily be extrapolated to humans, whether microwaves cause AD is an important issue that is to be addressed in the current review.