Birthweight by gestational age and childhood cancer

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Fetal growth and pediatric cancer: A pan-cancer analysis in 7000 cases and 37 000 controls

Birth weight is an established risk factor for some pediatric cancers but is dependent on gestational age and sex. Furthermore, it is unclear how associations may differ by infant sex, age at diagnosis, maternal race/ethnicity and maternal nativity status. We examined the association between size for gestation and a spectrum of pediatric cancers registered in the Texas Cancer Registry from 1995 to 2011. We analyzed up to 7547 cases and 37 735 controls. Analyses were conducted using logistic regression. Small-for-gestational age (SGA) and large-for-gestational age (LGA) were significantly associated with several tumors. SGA was associated with hepatic tumors (aOR = 1.76, 95% CI: 1.13, 2.74). Conversely, inverse associations were with Hodgkin lymphoma (aOR = 0.41, 95% CI: 0.19, 0.87) and soft tissue sarcomas (aOR = 0.65, 95% CI: 0.43, 0.97). LGA was associated with acute lymphoblastic leukemia (aOR = 1.37, 95% CI: 1.19, 1.57), Burkitt lymphoma (aOR = 1.90, 95% CI: 1.05, 3.45) and germ cell tumors (aOR = 1.55, 95% CI: 1.08, 2.23). Results did not differ when stratified by infant sex. The association with LGA and leukemia was strongest in those diagnosed 1 to 5 and 6 to 10 years. When stratified by maternal race/ethnicity, the association with LGA and neuroblastoma and renal tumors was strongest in children whose mother identified as non-Hispanic/Latina (H/L) Black. Among H/L women, children of Mexican-born women had a stronger association with LGA and leukemia, CNS tumors, neuroblastoma and renal tumors than children of US-born women (aOR range: 1.61-2.25 vs 1.12-1.27). Size for gestation is associated with several pediatric cancers. Associations may differ by age at diagnosis, maternal race/ethnicity and nativity.

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

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

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

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

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

INTRODUCTION

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

A History of Large for Gestational Age at Birth and Future Risk for Pediatric Neoplasms: A Population-Based Cohort Study

OBJECTIVE

The aim of this study was to evaluate the association between large for gestational age (LGA) at birth and future risk of childhood neoplasm.

STUDY DESIGN

a population-based cohort to compare the long-term risk (up to the age of 18 years) of childhood neoplasms (benign and malignant) in children that were born LGA vs. those that were appropriate for gestational age (AGA), between the years 1991-2014. Childhood neoplasms diagnosis were defined according to international classification of disease 9 (ICD-9) codes recorded medical files. Kaplan-Meier survival curves were used in order to compare cumulative incidence of oncological morbidity over the study period. The Cox proportional hazards model was used to control for confounders.

RESULTS

231,344 infants met the inclusion criteria; out of those 10,369 were diagnosed LGA at birth. Children that were LGA at birth had a higher incidence of leukemia (OR 2.25, 95%CI 1.08-4.65, p = 0.025) as well as kidney tumors (OR = 4.7, 95%CI = 1.02-21.9, p = 0.028). In addition, cumulative incidence over time of childhood malignancies, leukemia, and kidney tumors were significantly higher in LGA children (Log Rank = 0.010, 0.021, and 0.028, respectively). In a Cox regression model controlling for other perinatal confounders, LGA at birth remained independently associated with an increased risk for childhood malignancy (adjusted HR 1.51, 95%CI 1.02-2.23, p = 0.039).

CONCLUSION

LGA at birth is associated with increased long-term risk for childhood malignancy and specifically leukemia and kidney tumors. This possible link may help to improve current knowledge regarding potential exposures that are associated with childhood cancer development.

Age-, sex- and disease subtype-related foetal growth differentials in childhood acute myeloid leukaemia risk: A Childhood Leukemia International Consortium analysis

AIM

Evidence for an association of foetal growth with acute myeloid leukaemia (AML) is inconclusive. AML is a rare childhood cancer, relatively more frequent in girls, with distinct features in infancy. In the context of the Childhood Leukemia International Consortium (CLIC), we examined the hypothesis that the association may vary by age, sex and disease subtype using data from 22 studies and a total of 3564 AML cases.

METHODS

Pooled estimates by age, sex and overall for harmonised foetal growth markers in association with AML were calculated using the International Fetal and Newborn Growth Consortium for the 21st Century Project for 17 studies contributing individual-level data; meta-analyses were, thereafter, conducted with estimates provided ad hoc by five more studies because of administrative constraints. Subanalyses by AML subtype were also performed.

RESULTS

A nearly 50% increased risk was observed among large-for-gestational-age infant boys (odds ratio [OR]: 1.49, 95% confidence interval [CI]: 1.03-2.14), reduced to 34% in boys aged <2 years (OR: 1.34, 95% CI: 1.05-1.71) and 25% in boys aged 0-14 years (OR: 1.25, 95% CI: 1.06-1.46). The association of large for gestational age became stronger in boys with M0/M1subtype (OR: 1.80, 95% CI: 1.15-2.83). Large birth length for gestational age was also positively associated with AML (OR: 1.38, 95% CI: 1.00-1.92) in boys. By contrast, there were null associations in girls, as well as with respect to associations of decelerated foetal growth markers.

CONCLUSIONS

Accelerated foetal growth was associated with AML, especially in infant boys and those with minimally differentiated leukaemia. Further cytogenetic research would shed light into the underlying mechanisms.

Maternal and perinatal characteristics, congenital malformations and the risk of wilms tumor: the ESTELLE study

PURPOSE

Wilms tumor (WT), or nephroblastoma, is an embryonic tumor that constitutes the most common renal tumor in children. Little is known about the etiology of WT. The aim of this study was to investigate whether maternal or perinatal characteristics were associated with the risk of WT.

METHODS

The ESTELLE study is a national-based case-control study that included 117 cases of WT and 1,100 controls younger than 11 years old. The cases were children diagnosed in France in 2010-2011 and the controls were frequency matched with cases by age and gender. The mothers of case and control children responded to a telephone questionnaire addressing sociodemographic and perinatal characteristics, childhood environment, and lifestyle. Unconditional logistic regression models adjusted on potential cofounders were used to estimate the odds ratios (OR) and their confidence intervals (95% CI).

RESULTS

High birth weight and the presence of congenital malformation were associated with WT (OR 1.9 [95% CI 1.0-3.7] and OR 2.5 [95% CI 1.1-5.8], respectively). No association with breastfeeding or folic acid supplementation was observed.

CONCLUSIONS

Although potential recall bias cannot be excluded, our findings reinforce the hypothesis that high birth weight and the presence of congenital malformation may be associated with an increased risk of WT. Further investigations are needed to further elucidate the possible role of maternal characteristics in the etiology of WT.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Fetal programming and Wilms tumor

BACKGROUND

The "fetal programming" hypothesis has been evaluated in many adult diseases including cancer, but not for Wilms tumor. Wilms tumor has been related to high birthweight, but little is known about other growth metrics such as a baby's birth length, ponderal index, or placenta size, which can shed additional light on growth patterns.

METHODS

Cases of Wilms tumor (N = 217) were taken from the Danish Cancer Registry, and controls (N = 4340) were randomly selected from the Population Register and matched to cases by sex and age. Linkage to the Medical Births Registry provided information on gestational factors and fetal growth measurements, while linkage to the Patient Register provided information on maternal and child health conditions.

RESULTS

Despite having typically normal to higher birthweights, Wilms tumor cases had smaller placentas (≤540 g; odds ratio (OR) = 4.24; 95% confidence interval (CI), 1.84-9.78) and a lower placenta-to-birthweight ratio (OR = 1.81; 95% CI, 1.17-2.82, per 1 SD decrease). Small placentas were more common among Wilms cases without congenital anomalies (OR = 6.43; 95% CI, 1.95-21.21). Wilms tumor cases had a higher prevalence of high birthweight (>4000 g; OR = 1.57; 95% CI, 1.11-2.22), birth length 55 cm or longer (OR = 1.74; 95% CI, 1.09-2.78), and being large for gestational age (OR = 1.79; 95% CI, 1.08-2.96).

CONCLUSIONS

Our study corroborates earlier studies showing associations with high birthweight and suggests associations between Wilms tumor and decreased placental size and low placenta-to-birthweight ratio.

The association between high birth weight and the risks of childhood CNS tumors and leukemia: an analysis of a US case-control study in an epidemiological database

Background

High birth weight (BW), 4000 g or larger, is an established risk factor for childhood leukemia. However, its association with central nervous system (CNS) tumor risk is yet unclear. The present study examined it, analyzing data obtained from a case-control study conducted among three states from the US. The association with childhood leukemia risk was also further examined.

Methods

In this study, a data set provided by the Comprehensive Epidemiologic Data Resource was analyzed with an official permission. The original case-control study was conducted to examine the association between paternal preconception exposure to ionizing radiation and childhood cancer risk. Cases with childhood cancer were mainly ascertained from local hospitals, and controls were selected, matched with birth year (1-year category), county of residence, sex, ethnicity and maternal age (+/−2 years). Since the ID numbers were unavailable, conventional logistic analyses were conducted adjusting for those matching variables except for the county of residence. In addition to those variables, gestational age, age at diagnosis and study sites as covariables were included in the logistic models.

Results

Analyzed subjects were 72 CNS tumor cases, 124 leukemia cases and 822 controls born from 1945 to 1989. The odds ratios (ORs) of CNS tumor risk for children with low BWs (<2500 g) and high BWs (>4000 g) were 2.0 (95% confidence interval [CI]) = 0.7, 5.9) and 2.5 (95%CI = 1.2, 5.2)], respectively. When high-BW children were restricted to those who were large for gestational age (LGA), the OR for high-BW children remained similar (OR = 2.7; 95%CI = 1.1, 6.2). On the other hand, the ORs of leukemia risk for children with low and high BWs were 0.8 (95%CI = 0.2, 3.0) and 1.4 (95%CI = 0.7, 2.6), respectively. In the normal range of BW (2500–4000 g), higher BW was positively associated with CNS tumor risk (beta = 0.0011, p for trend = 0.012). However, the association with leukemia risk was not significant (beta = −0.0002, p for trend = 0.475).

Conclusion

High-BW and LGA children had an elevated childhood CNS tumor risk. In the normal BW range, the BW itself was positively related to CNS tumor risk. No significant association between BW and childhood leukemia risk was observed in this study.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3681-y) contains supplementary material, which is available to authorized users.

Perinatal factors associated with clinical presentation of osteosarcoma in children and adolescents

BACKGROUND

Osteosarcoma typically develops during puberty with tumors arising at sites of rapid bone growth, suggesting a role for growth-regulating pathways in tumor etiology. Birthweight is one measure of perinatal growth that has been investigated as an osteosarcoma risk factor. Whether birthweight affects clinical features of osteosarcoma remains unexplored.

METHOD

Six hundred seventy patients with osteosarcoma, aged 0-19 years, were identified through the California Cancer Registry. We analyzed birth certificate data from the California Department of Public Health vital statistics unit for these patients and 2,860 controls, matched by sex, birth-year, and race/ethnicity. We examined the impact of birthweight on the risk, timing, and clinical presentation of pediatric osteosarcoma including tumor location, size, extension, differentiation, presence of metastasis, and age at onset. Regression models were adjusted for race, sex, gestational age, socioeconomic status, and tumor site.

RESULTS

Higher birthweight was associated with more advanced tumor stage (P = 0.017), a trend toward greater tumor extension into surrounding tissues (P = 0.083), and with occurrence of tumors in sites other than the long bones of the arms/legs (P = 9.7 × 10^-3 ). Higher birthweight was also associated with an increased likelihood of metastases present at diagnosis (P = 0.047), with each 200 g increase in birthweight associated with a 1.11-fold increase in the odds of having metastatic disease (95% confidence interval: 1.01-1.22).

CONCLUSIONS

The association between higher birthweight and more aggressive osteosarcoma, frequently occurring at sites other than the long bones, suggests that growth pathways active during gestation may play an important role in future osteosarcoma progression, especially at anatomic sites with diminished rates of osteoblastic proliferation.

Anthropometrics at birth and risk of a primary central nervous system tumour: A systematic review and meta-analysis

BACKGROUND

The aetiology of primary central nervous system (CNS) tumours remains largely unknown, but their childhood peak points to perinatal parameters as tentative risk factors. In this meta-analysis, we opted to quantitatively synthesise published evidence on the association between birth anthropometrics and risk of primary CNS tumour.

METHODS

Eligible studies were identified via systematic literature review; random-effects meta-analyses were conducted for the effect of birth weight and size-for-gestational-age on childhood and adult primary CNS tumours; subgroup, sensitivity, meta-regression and dose-response by birth weight category analyses were also performed.

RESULTS

Forty-one articles, encompassing 53,167 CNS tumour cases, were eligible. Birth weight >4000 g was associated with increased risk of childhood CNS tumour (OR: 1.14, [1.08-1.20]; 22,330 cases). The risk was higher for astrocytoma (OR: 1.22, [1.13-1.31]; 7456 cases) and embryonal tumour (OR: 1.16, [1.04-1.29]; 3574 cases) and non-significant for ependymoma (OR: 1.12, [0.94-1.34]; 1374 cases). Increased odds for a CNS tumour were also noted among large-for-gestational-age children (OR: 1.12, [1.03-1.22]; 10,339 cases), whereas insufficient data for synthesis were identified for other birth anthropometrics. The findings remained robust across subgroup and sensitivity analyses controlling for several sources of bias, whereas no significant heterogeneity or publication bias were documented. The limited available evidence on adults (4 studies) did not reveal significant associations between increasing birth weight (500-g increment) and overall risk CNS tumour (OR: 0.99, [0.98-1.00]; 1091 cases) or glioma (OR: 1.03, [0.98-1.07]; 2052 cases).

CONCLUSIONS

This meta-analysis confirms a sizeable association of high birth weight, with childhood CNS tumour risk, particularly astrocytoma and embryonal tumour, which seems to be independent of gestational age. Further research is needed to explore underlying mechanisms, especially modifiable determinants of infant macrosomia, such as gestational diabetes.

A Vulnerable Age for the Introduction of Solid Foods in Pediatric Acute Lymphoblastic Leukemia

BACKGROUND

There is little research concerning infant formula or the age at introduction to solid foods and pediatric acute lymphoblastic leukemia (ALL). The purpose of this case-control study was to estimate the association of age at introduction of solids and pediatric ALL.

METHODS

171 ALL cases aged 0-14 years were recruited at Texas Children's Cancer Center and matched on sex, age, and ethnicity to 342 population-based controls. Data were collected on infant feeding and known risk factors for ALL. Multivariable logistic regression was used to model the odds ratio of ALL by quartile of age at introduction of solids with the first/earliest quartile (0-4 months) as the reference group.

RESULTS

In adjusted models, the odds ratio of ALL among children in quartile 3 (7-9 months) was 4.08, 95% confidence interval (CI) 1.42-11.71; for children in quartile 4 (≥10 months) the odds ratio (OR) was 6.03, 95% CI 2.06-17.72. For each additional month of milk formula feeding, the OR of ALL was 1.16, 95% CI 1.08-1.25.

CONCLUSIONS

These results suggest a window when later introduction to solids is positively associated with ALL and recommend compliance with the American Academy of Pediatrics guidelines.

Household Food Insecurity is Associated with Childhood Asthma

BACKGROUND

In 2013, 20% of U.S. households with children experienced food insecurity. Asthma afflicts over 7 million children; prevalence has steadily increased while incidence peaks in young children. Asthma and food insecurity share the determinants of poverty and race that are associated with weight, yet limited research on the relation between food insecurity and asthma exists.

OBJECTIVE

The objective of this study was to determine the association between food insecurity and asthma in a diverse sample of children.

METHODS

Cross-sectional data from grade 3 of the Early Childhood Longitudinal Study-Kindergarten Cohort were analyzed (n = 11,099). Food security based on the USDA module and asthma diagnosis were reported by parents; anthropometric factors were measured. Multivariate logistic regression models of food security and asthma were analyzed overall and by race/ethnicity.

RESULTS

Children in food-insecure households had a 4% higher adjusted odds of asthma (95% CI: 1.02, 1.06). Adjusted odds of asthma were also higher by 70% for males (95% CI: 1.69, 1.71), 53% for non-Hispanic black (NHB) children (95% CI: 1.51, 1.54), 20% for Hispanic children (95% CI: 1.19, 1.21), 38% for overweight children (95% CI: 1.36, 1.39), 67% for obese children (95% CI: 1.65, 1.68), 23% for low-birth weight children (95% CI: 1.21, 1.24), 24% if mothers had a high school diploma (95% CI: 1.23, 1.26), and 33% if mothers had some college education (95% CI: 1.32, 1.35). High-birth weight children (OR: 0.84; 95% CI: 0.83, 0.85) and those with foreign-born mothers (OR: 0.52; 95% CI: 0.51, 0.53) had lower odds of asthma. Being food-insecure remained positively associated with asthma in non-Hispanic whites and Hispanics but was inversely associated with odds among NHBs. Odds of asthma doubled (OR: 2.00; 95% CI: 1.97, 2.03) for all children in households that were both food-insecure and poor; this relation remained positive in race/ethnicity-specific models.

CONCLUSIONS

Food insecurity is positively associated with asthma in U.S. third graders, and household poverty strengthens the association.

Birth order and risk of childhood cancer in the Danish birth cohort of 1973-2010

PURPOSE

Many studies have investigated the possible association between birth order and risk of childhood cancer, although the evidence to date has been inconsistent. Birth order has been used as a marker for various in utero or childhood exposures and is relatively straightforward to assess.

METHODS

Data were obtained on all children born in Denmark between 1973 and 2010, involving almost 2.5 million births and about 5,700 newly diagnosed childhood cancers before the age of 20 years. Data were analyzed using Poisson regression models.

RESULTS

We failed to observe associations between birth order and risk of any childhood cancer subtype, including acute lymphoblastic leukemia; all rate ratios were close to one. Further analyses stratified by birth cohort (those born between 1973 and 1990, and those born between 1991 and 2010) also failed to show any associations. Considering stillbirths and/or controlling for birth weight and parental age in the analyses had no effect on the results. Analyses by years of birth (those born between 1973 and 1990, and those born between 1991 and 2010) did not show any changes in the overall pattern of no association.

CONCLUSIONS

In this large cohort of all children born in Denmark over an almost 40-year period, we did not observe an association between birth order and the risk of childhood cancer.

High Birth Weight Increases the Risk for Bone Tumor: A Systematic Review and Meta-Analysis

There have been several epidemiologic studies on the relationship between high birth weight and the risk for bone tumor in the past decades. However, due to the rarity of bone tumors, the sample size of individual studies was generally too small for reliable conclusions. Therefore, we have performed a meta-analysis to pool all published data on electronic databases with the purpose to clarify the potential relationship. According to the inclusion and exclusion criteria, 18 independent studies with more than 2796 cases were included. As a result, high birth weight was found to increase the risk for bone tumor with an Odds Ratio (OR) of 1.13, with the 95% confidence interval (95% CI) ranging from 1.01 to 1.27. The OR of bone tumor for an increase of 500 gram of birth weight was 1.01 (95% CI 1.00–1.02; p = 0.048 for linear trend). Interestingly, individuals with high birth weight had a greater risk for osteosarcoma (OR = 1.22, 95% CI 1.06–1.40, p = 0.006) than those with normal birth weight. In addition, in the subgroup analysis by geographical region, elevated risk was detected among Europeans (OR = 1.14, 95% CI 1.00–1.29, p = 0.049). The present meta-analysis supported a positive association between high birth weight and bone tumor risk.

The associations between maternal factors during pregnancy and the risk of childhood acute lymphoblastic leukemia: A meta-analysis

BACKGROUND

Although genetic and environmental factors are considered to be the main causes of acute lymphoblastic leukemia, the associations between maternal factors during pregnancy and the childhood ALL is still unclear.

PROCEDURE

In this study, meta-analysis was used. Medline, PubMed, and Web of Science were searched. The result was assessed based on pooled odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

The pooled ORs showed that there were associations between childhood ALL and the birth order (The first vs others, OR = 1.08, 95%CI = 1.00-1.16), the education of pregnant woman (>high school vs ≤ high school, OR = 0.82, 95%CI = 0.77-0.86), smoking (Ever vs never, OR = 1.10, 95%CI = 1.02-1.19).

CONCLUSIONS

Our meta-analysis showed that there were important associations between childhood ALL and the birth order, the education of pregnant woman, smoking.

Birthweight and Childhood Cancer: Preliminary Findings from the International Childhood Cancer Cohort Consortium (I4C)

BACKGROUND

Evidence relating childhood cancer to high birthweight is derived primarily from registry and case-control studies. We aimed to investigate this association, exploring the potential modifying roles of age at diagnosis and maternal anthropometrics, using prospectively collected data from the International Childhood Cancer Cohort Consortium.

METHODS

We pooled data on infant and parental characteristics and cancer incidence from six geographically and temporally diverse member cohorts [the Avon Longitudinal Study of Parents and Children (UK), the Collaborative Perinatal Project (USA), the Danish National Birth Cohort (Denmark), the Jerusalem Perinatal Study (Israel), the Norwegian Mother and Child Cohort Study (Norway), and the Tasmanian Infant Health Survey (Australia)]. Birthweight metrics included a continuous measure, deciles, and categories (≥ 4.0 vs. < 4.0 kilogram). Childhood cancer (377 cases diagnosed prior to age 15 years) risk was analysed by type (all sites, leukaemia, acute lymphoblastic leukaemia, and non-leukaemia) and age at diagnosis. We estimated hazard ratios (HR) and 95% confidence intervals (CI) from Cox proportional hazards models stratified by cohort.

RESULTS

A linear relationship was noted for each kilogram increment in birthweight adjusted for gender and gestational age for all cancers [HR = 1.26; 95% CI 1.02, 1.54]. Similar trends were observed for leukaemia. There were no significant interactions with maternal pre-pregnancy overweight or pregnancy weight gain. Birthweight ≥ 4.0 kg was associated with non-leukaemia cancer among children diagnosed at age ≥ 3 years [HR = 1.62; 95% CI 1.06, 2.46], but not at younger ages [HR = 0.7; 95% CI 0.45, 1.24, P for difference = 0.02].

CONCLUSION

Childhood cancer incidence rises with increasing birthweight. In older children, cancers other than leukaemia are particularly related to high birthweight. Maternal adiposity, currently widespread, was not demonstrated to substantially modify these associations. Common factors underlying foetal growth and carcinogenesis need to be further explored.

Perinatal and familial risk factors for acute lymphoblastic leukemia in a Swedish national cohort

BACKGROUND

Perinatal factors including high birth weight have been found to be associated with acute lymphoblastic leukemia (ALL) in case-control studies. However, to the best of our knowledge, these findings have seldom been examined in large population-based cohort studies, and the specific contributions of gestational age and fetal growth remain unknown.

METHODS

The authors conducted a national cohort study of 3,569,333 individuals without Down syndrome who were born in Sweden between 1973 and 2008 and followed for the incidence of ALL through 2010 (maximum age, 38 years) to examine perinatal and familial risk factors.

RESULTS

There were 1960 ALL cases with 69.7 million person-years of follow-up. After adjusting for potential confounders, risk factors for ALL included high fetal growth (incidence rate ratio [IRR] per additional 1 standard deviation, 1.07; 95% confidence interval [95% CI], 1.02-1.11 [P =.002]; and IRR for large vs appropriate for gestational age, 1.22; 95% CI, 1.06-1.40 [P =.005]), first-degree family history of ALL (IRR, 7.41; 95% CI, 4.60-11.95 [P<.001]), male sex (IRR, 1.20; 95% CI, 1.10-1.31 [P<.001]), and parental country of birth (IRR for both parents born in Sweden vs other countries, 1.13; 95% CI, 1.00-1.27 [P =.045]). These risk factors did not appear to vary by patient age at the time of diagnosis of ALL. Gestational age at birth, season of birth, birth order, multiple birth, parental age, and parental education level were not found to be associated with ALL.

CONCLUSIONS

In this large cohort study, high fetal growth was found to be associated with an increased risk of ALL in childhood through young adulthood, independent of gestational age at birth, suggesting that growth factor pathways may play an important long-term role in the etiology of ALL.

Factors relating to pregnancy and birth and the risk of childhood brain tumors: results from an Australian case-control study

BACKGROUND

Childhood brain tumors (CBT) are the leading cause of cancer death in children, yet their causes are largely known. This study investigated the association between maternal and birth characteristics and risk of CBT.

PROCEDURES

Cases families were recruited from all 10 Australian pediatric oncology centers between 2005 and 2010. Control families were recruited via random-digit dialing, frequency matched to cases on the basis of child's age, sex, and State of residence. Maternal and birth characteristics of children were ascertained by questionnaires. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated using unconditional logistic regression, adjusting for relevant confounders.

RESULTS

For this analysis, data on 319 case children and 1,079 control children were available. No association was found between risk of CBT and birth weight, fetal growth, birth order, gestational age, or maternal body mass index. The ORs for inadequate and excessive maternal gestational weight gain (GWG) (Institute of Medicine 2009 guidelines) were 1.8 (95% CI 1.2-2.6) and 1.4 (95% CI 1.0-2.1), respectively; similar findings for GWG were seen across categories of child's age, fetal growth, maternal body mass index and height, maternal smoking, and parental education. Risk of low grade glioma appeared increased with preterm birth (OR 1.6 (95% CI 0.8-3.1) and admission to neonatal intensive care (NICU) for >2 days (OR 1.7, 95% CI 0.9-3.6).

CONCLUSION

We found little evidence of associations between risk of CBT and most birth characteristics. The associations we observed with GWG, prematurity and NICU admission require corroboration in other studies.

Fetal growth and childhood cancer: a population-based study

OBJECTIVE

The etiology of childhood cancers is largely unknown. Studies have suggested that birth characteristics may be associated with risk. Our goal was to evaluate the risk of childhood cancers in relation to fetal growth.

METHODS

We conducted a case-control study nested within Nordic birth registries. The study included cancer cases diagnosed in Denmark, Finland, Norway, and Sweden among children born from 1967 to 2010 and up to 10 matched controls per case, totaling 17,698 cases and 172,422 controls. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were derived from conditional logistic regression.

RESULTS

Risks of all childhood cancers increased with increasing birth weight (P trend ≤ .001). Risks of acute lymphoid leukemia and Wilms tumor were elevated when birth weight was >4000 g and of central nervous system tumors when birth weight was >4500 g. Newborns large for gestational age were at increased risk of Wilms tumor (OR: 2.1 [95% CI: 1.2-3.6]) and connective/soft tissue tumors (OR: 2.1 [95% CI: 1.1-4.4]). In contrast, the risk of acute myeloid leukemia was increased among children born small for gestational age (OR: 1.8 [95% CI: 1.1-3.1]). Children diagnosed with central nervous system tumors at <1 year of age had elevated risk with increasing head circumference (P trend < .001). Those with head circumference >39 cm had the highest risk (OR: 4.7 [95% CI: 2.5-8.7]).

CONCLUSIONS

In this large, Nordic population-based study, increased risks for several childhood tumors were associated with measures of fetal growth, supporting the hypothesis that tumorigenesis manifesting in childhood is initiated in utero.

Fetal growth and childhood acute lymphoblastic leukemia: findings from the childhood leukemia international consortium

Positive associations have been reported between the measures of accelerated fetal growth and risk of childhood acute lymphoblastic leukemia (ALL). We investigated this association by pooling individual-level data from 12 case-control studies participating in the Childhood Leukemia International Consortium. Two measures of fetal growth-weight-for-gestational-age and proportion of optimal birth weight (POBW)-were analysed. Study-specific odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression, and combined in fixed effects meta-analyses. Pooled analyses of all data were also undertaken using multivariable logistic regression. Subgroup analyses were undertaken when possible. Data on weight for gestational age were available for 7,348 cases and 12,489 controls from all 12 studies and POBW data were available for 1,680 cases and 3,139 controls from three studies. The summary ORs from the meta-analyses were 1.24 (95% CI: 1.13, 1.36) for children who were large for gestational age relative to appropriate for gestational age, and 1.16 (95% CI: 1.09, 1.24) for a one-standard deviation increase in POBW. The pooled analyses produced similar results. The summary and pooled ORs for small-for-gestational-age children were 0.83 (95% CI: 0.75, 0.92) and 0.86 (95% CI: 0.77, 0.95), respectively. Results were consistent across subgroups defined by sex, ethnicity and immunophenotype, and when the analysis was restricted to children who did not have high birth weight. The evidence that accelerated fetal growth is associated with a modest increased risk of childhood ALL is strong and consistent with known biological mechanisms involving insulin-like growth factors. © 2013 UICC.

The epidemiology of sarcoma

Sarcomas account for over 20% of all pediatric solid malignant cancers and less than 1% of all adult solid malignant cancers. The vast majority of diagnosed sarcomas will be soft tissue sarcomas, while malignant bone tumors make up just over 10% of sarcomas. The risks for sarcoma are not well-understood. We evaluated the existing literature on the epidemiology and etiology of sarcoma. Risks for sarcoma development can be divided into environmental exposures, genetic susceptibility, and an interaction between the two. HIV-positive individuals are at an increased risk for Kaposi's sarcoma, even though HHV8 is the causative virus. Radiation exposure from radiotherapy has been strongly associated with secondary sarcoma development in certain cancer patients. In fact, the risk of malignant bone tumors increases as the cumulative dose of radiation to the bone increases (p for trend <0.001). A recent meta-analysis reported that children with a history of hernias have a greater risk of developing Ewing's sarcoma (adjusted OR 3.2, 95% CI 1.9, 5.7). Bone development during pubertal growth spurts has been associated with osteosarcoma development. Occupational factors such as job type, industry, and exposures to chemicals such as herbicides and chlorophenols have been suggested as risk factors for sarcomas. A case-control study found a significant increase in soft tissue sarcoma risk among gardeners (adjusted OR 4.1, 95% CI 1.00, 14.00), but not among those strictly involved in farming. A European-based study reported an increased risk in bone tumors among blacksmiths, toolmakers, or machine-tool operators (adjusted OR 2.14, 95% CI 1.08, 4.26). Maternal and paternal characteristics such as occupation, age, smoking status, and health conditions experienced during pregnancy also have been suggested as sarcoma risk factors and would be important to assess in future studies. The limited studies we identified demonstrate significant relationships with sarcoma risk, but many of these results now require further validation on larger populations. Furthermore, little is known about the biologic mechanisms behind each epidemiologic association assessed in the literature. Future molecular epidemiology studies may increase our understanding of the genetic versus environmental contributions to tumorigenesis in this often deadly cancer in children and adults.

Perinatal characteristics and retinoblastoma

PURPOSE

The etiology of retinoblastoma remains poorly understood. In the present study, we examined associations between perinatal factors and retinoblastoma risk in California children.

METHODS

We identified 609 retinoblastoma cases (420 unilateral, 187 bilateral, and 2 with laterality unknown) from California Cancer Registry records of diagnoses 1988-2007 among children < 6 years of age. We randomly selected 209,051 controls from California birth rolls. The source of most study data was birth certificates. Multivariable logistic regression was used to examine associations between retinoblastoma and perinatal characteristics.

RESULTS

Bilateral retinoblastoma was associated with greater paternal age [for fathers over 35, crude odds ratio (OR) = 1.73, 95 % confidence interval (CI) 1.20, 2.47] and with twin births (OR = 1.93, 95 % CI 0.99, 3.79). Among unilateral cases, we observed an increased risk among children of US-born Hispanic mothers (OR = 1.34, 95 % CI 1.01, 1.77) while a decreased risk was observed for infants born to mothers with less than 9 years of education (OR = 0.70, 95 % CI 0.49, 1.00), a group that consisted primarily of mothers born in Mexico. We observed that maternal infection in pregnancy with any STD (OR = 3.59, 95 % CI 1.58, 8.15) was associated with bilateral retinoblastoma.

CONCLUSIONS

This study supports the findings of previous investigations reporting associations between parental age, HPV infection, and retinoblastoma.

Birth weight and other perinatal characteristics and childhood leukemia in California

AIMS

We conducted a large registry-based study in California to investigate the association of perinatal factors and childhood leukemia with analysis of two major subtypes, acute lymphocytic leukemia (ALL) and acute myeloid leukemia (AML).

METHODS

We linked California cancer and birth registries to obtain information on 5788 cases and 5788 controls matched on age and sex (1:1). We examined the association of birth weight, gestational age, birth and pregnancy order, parental ages, and specific conditions during pregnancy and risk of total leukemia, ALL and AML using conditional logistic regression, with adjustment for potential confounders.

RESULTS

The odds ratio (OR) per 1000 g increase in birth weight was 1.11 for both total leukemia and ALL. The OR were highest for babies weighing ≥ 4500 g with reference < 2500 g: 1.59 (95% CI: 1.05-2.40) and 1.70 (95% CI: 1.08-2.68) for total leukemia and ALL, respectively. For AML, increase in risk was also observed but the estimate was imprecise due to small numbers. Compared to average-for-gestational age (AGA), large-for-gestational age (LGA) babies were at slightly increased risk of total childhood leukemia (OR = 1.10) and both ALL and AML (OR = 1.07 and OR = 1.13, respectively) but estimates were imprecise. Being small-for-gestational age (SGA) was associated with reduced risk of childhood leukemia (OR = 0.81, 95% CI: 0.67-0.97) and ALL (OR = 0.77, 95% CI: 0.63-0.94), but not AML. Being first-born was associated with decreased risk of AML only (OR = 0.70; 95% CI: 0.53-0.93). Compared to children with paternal age <25 years, children with paternal age between 35 and 45 years were at increased risk of total childhood leukemia (OR = 1.12; 95% CI: 1.04-1.40) and ALL (OR = 1.23; 95% CI: 1.04-1.47). None of conditions during pregnancy examined or maternal age were associated with increased risk of childhood leukemia or its subtypes.

CONCLUSIONS

Our results suggest that high birth weight and LGA were associated with increased risk and SGA with decreased risk of total childhood leukemia and ALL, being first-born was associated with decreased risk of AML, and advanced paternal age was associated with increased risk of ALL. These findings suggest that associations of childhood leukemia and perinatal factors depend highly on subtype of leukemia.

Involvement of the IGF system in fetal growth and childhood cancer: an overview of potential mechanisms

Fetal growth is determined by a complex interplay of genetic, nutritional, environmental, and hormonal factors. Greater than expected fetal growth has been positively associated with the risk of the development of some cancers in childhood, particularly acute lymphoblastic leukemia, and the biological mechanisms underlying such associations are thought to involve insulin-like growth factors (IGFs). Circulating IGF levels are highly correlated with fetal growth, and IGFs are believed to play an important role in carcinogenesis; however, these two bodies of evidence have not been well integrated and, as a result, the potential underlying biological mechanisms linking the IGF system with the development of specific childhood cancers have not been elucidated. This review aims to draw together and summarize the literature linking the IGF system, rapidity of fetal growth, and risk of some specific childhood cancers; suggest explanations for some of the inconsistencies observed in previous studies of these associations; and propose an integrated framework for the putative involvement of the IGF system in the development of at least some childhood cancers. If the challenges involved in studying the complex IGF system can be overcome, this field presents an exciting opportunity to elucidate etiological pathways to childhood malignancies.

Height at diagnosis and birth-weight as risk factors for osteosarcoma

OBJECTIVES

Osteosarcoma typically occurs during puberty. Studies of the association between height and/or birth-weight and osteosarcoma are conflicting. Therefore, we conducted a large pooled analysis of height and birth-weight in osteosarcoma.

METHODS

Patient data from seven studies of height and three of birth-weight were obtained, resulting in 1,067 cases with height and 434 cases with birth-weight data. We compared cases to the 2000 US National Center for Health Statistics Growth Charts by simulating 1,000 age- and gender-matched controls per case. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for associations between height or birth-weight and risk of osteosarcoma for each study were estimated using logistic regression. All of the case data were combined for an aggregate analysis.

RESULTS

Compared to average birth-weight subjects (2,665-4,045 g), individuals with high birth-weight (≥ 4,046 g) had an increased osteosarcoma risk (OR 1.35, 95% CI 1.01-1.79). Taller than average (51st - 89th percentile) and very tall individuals (≥ 90th percentile) had an increased risk of osteosarcoma (OR 1.35, 95% CI 1.18-1.54 and OR 2.60, 95% CI 2.19-3.07, respectively; P (trend) < 0.0001).

CONCLUSIONS

This is the largest analysis of height at diagnosis and birth-weight in relation to osteosarcoma. It suggests that rapid bone growth during puberty and in utero contributes to OS etiology.

Birth characteristics and Wilms tumors in children in the Nordic countries: a register-based case-control study

Little is known about causes of Wilms tumor. Because of the young age at diagnosis, several studies have looked at various birth characteristics. We conducted a registry-based case-control study involving 690 cases of Wilms tumor aged 0-14 years, occurring in Denmark, Finland, Norway or Sweden during 1985-2006, individually matched to five controls drawn randomly from the Nordic childhood population. Information on birth characteristics was obtained from the population-based medical birth registries. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using conditional logistic regression analysis. We observed a distinct association between Wilms tumor and high birth weight (≥4 kg) for girls (OR 1.97, CI 1.50-2.59) but not for boys (1.04, 0.78-1.38); overall, the OR was 1.43 (1.17-1.74). Among girls, risk increased by 28% (15-42%) per 500 g increase in birth weight. Large-for-gestational age girls also had a higher risk (2.48, 1.51-4.05), whereas no effect was seen for boys (1.12, 0.60-2.07). An association was seen with Apgar score at 5 min < 7 for both sexes combined (5.13, 2.55-10.3). ORs close to unity were seen for parental age and birth order. In our large-scale, registry-based study, we confirmed earlier observations of an association between high birth weight and risk of Wilms tumor, but we found an effect only in girls. The higher risk of infants with low Apgar score might reflect hypoxia causing cell damage, adverse side effects of neonatal treatment or reverse causation as low Apgar score might indicate the presence of a tumor.

Is birth weight associated with childhood lymphoma? A meta-analysis

Several risk factors have been identified for childhood lymphomas. The purpose of this meta-analysis was to synthesize current evidence regarding the association between birth weight with primarily the risk for non-Hodgkin lymphoma (NHL), given its similarity to acute lymphoblastic leukemia, Hodgkin lymphoma (HL) and any category of lymphoma. Two cohort (278,751 children) and seven case-control studies (2,660 cases and 69,274 controls) were included. Effects estimates regarding NHL, HL and any lymphoma were appropriately pooled using fixed or random effects model in two separate analyses: specifically, high was compared to normal or any birth weight. Similarly, low was compared to normal or any birth weight. No statistically significant association was found between high birth weight, as compared to normal birth weight, and risk for NHL plus Burkitt lymphoma (OR = 1.17, 95% CI = 0.76-1.80, random effects), HL (OR = 0.94, 95% CI = 0.64-1.38, fixed effects) or any plus Burkitt lymphoma (OR = 1.09, 95% CI = 0.76-1.56, fixed effects). A null association emerged when low was compared with normal birth weight for NHL plus Burkitt lymphoma (OR = 1.07, 95% CI = 0.71-1.62, random effects), HL (OR = 0.94, 95% CI = 0.54-1.65, fixed effects) or any plus Burkitt lymphoma (OR = 1.02, 95% CI = 0.79-1.33, fixed effects). Accordingly, no association was found when high or low birth weight was compared to any birth weight. Although current evidence suggests no association, birth weight might be a too crude indicator to reveal a genuine association of fetal growth with specific lymphoma categories; hence, there is an emerging need for use of more elaborate proxies, at least those accounting for gestational week.

Using epidemiology and genomics to understand osteosarcoma etiology

Osteosarcoma is a primary bone malignancy that typically occurs during adolescence but also has a second incidence peak in the elderly. It occurs most commonly in the long bones, although there is variability in location between age groups. The etiology of osteosarcoma is not well understood; it occurs at increased rates in individuals with Paget disease of bone, after therapeutic radiation, and in certain cancer predisposition syndromes. It also occurs more commonly in taller individuals, but a strong environmental component to osteosarcoma risk has not been identified. Several studies suggest that osteosarcoma may be associated with single nucleotide polymorphisms in genes important in growth and tumor suppression but the studies are limited by sample size. Herein, we review the epidemiology of osteosarcoma as well as its known and suspected risk factors in an effort to gain insight into its etiology.

Birth weight and order as risk factors for childhood central nervous system tumors

OBJECTIVE

To determine whether birth characteristics related to maternal-fetal health in utero are associated with the development of childhood central nervous system tumors.

STUDY DESIGN

We identified, from the California Cancer Registry, 3733 children under age 15 diagnosed with childhood central nervous system tumors between 1988 and 2006 and linked these cases to their California birth certificates. Four controls per case, matched on birth date and sex, were randomly selected from the same birth files. We evaluated associations of multiple childhood CNS tumor subtypes with birth weight and birth order.

RESULTS

Low birth weight was associated with a reduced risk of low-grade gliomas (OR=0.67; 95% CI, 0.46 to 0.97) and high birth weight was associated with increased risk of high-grade gliomas (OR=1.57; 95% CI, 1.16 to 2.12). High birth order (fourth or higher) was associated with decreased risk of low-grade gliomas (OR=0.75; 95% CI, 0.56 to 0.99) and increased risk of high-grade gliomas (OR=1.32; 95% CI, 1.01 to 1.72 for second order).

CONCLUSIONS

Factors that drive growth in utero may increase the risk of low-grade gliomas. There may be a similar relationship in high-grade gliomas, although other factors, such as early infection, may modify this association. Additional investigation is warranted to validate and further define these findings.

Wilms' tumour: a systematic review of risk factors and meta-analysis

Wilms' tumour comprises 95% of all renal cancers among children less than 15 years of age. The purpose of this review is to examine the existing literature on perinatal and environmental risk factors for Wilms' tumour. A search for epidemiological studies that examined risk factors for Wilms' tumour was undertaken in Medline, LILACS, ISI Web of Science and Dissertation Abstracts. A total of 37 studies, including 14 cohort, 21 case-control and 2 case-cohort studies, were identified that examined environmental and perinatal risk factors. Most studies were from Western Europe and North America, and among case-control studies, 16 used randomly selected population-based controls. We observed a significantly increased risk of Wilms' tumour with maternal exposure to pesticides prior to the child's birth (OR = 1.37 [95% CI 1.09, 1.73]), high birthweight (OR = 1.36 [95% CI 1.12, 1.64]) and preterm birth (OR = 1.44 [95% CI 1.14, 1.81]), although the results regarding pesticide exposure may be subject to publication bias (Egger's test, P = 0.09). Further analyses to adjust for the heterogeneity in the results for high birthweight and preterm birth did not statistically change the significance of the results. Additionally, an increased though not statistically significant risk of Wilms' tumour was associated with maternal hypertension (OR = 1.30 [95% CI 0.99, 1.72]), and, compared with the first born, being a second or later birth was associated with a significantly decreased risk (OR = 0.82 [95% CI 0.71, 0.95]). This review suggests a role for several perinatal and environmental risk factors in the aetiology of Wilms' tumour.

Leukemia, non-Hodgkin's lymphoma, and Wilms tumor in childhood: the role of birth weight

There is emerging evidence that higher birth weight is associated with increased risk of cancer, in particular childhood leukemia. The purpose of this paper is to study whether this correlation is also significant with other childhood cancer. For this, we conducted a case-control study including 410 childhood cancer patients and 1,575 matched controls to investigate birth weight as a risk factor for leukemia, Wilms tumor, and non-Hodgkin's lymphoma. The estimated risk for all cancers has been found to be statistically and significantly higher in birth weight of more than 4,000 g (odds ratio, 2.50 and 95% confidence intervals (CI), 1.72-3.63). For leukemia, the estimated risk was 1.86 (95% CI, 1.04-3.30), for non-Hodgkin lymphoma, 1.99 (95% CI, 1.08-3.69), and being more remarkable for Wilms tumor, 4.76 (95% CI, 2.73-8.28). Moreover, moderate increased risk of both leukemia and non-Hodgkin lymphoma was also associated with birth weight between 3,000 and 3,999 g. High birth weight was associated with all cancers also when adjusted by gestational age, length at birth, and gender (odds ratio, 6.10 and 95% CI, 1.15-32.57). No associations were found for maternal alcohol consumption during pregnancy, maternal smoking, or smoking by other people at home or presence of obstetric variables (e.g., gestational diabetes, preeclampsia, and abruptio placentae). The present study supports the hypothesis that high birth weight is an independent risk factor for childhood Wilms tumor, leukemia, and non-Hodgkin lymphoma. Further studies should explore biological reasons to explain this relationship and, ultimately, to expand our knowledge about prenatal influences on the occurrence of this disease.

Birth weight and risk of neuroblastoma: a meta-analysis

BACKGROUND

Neuroblastoma is the most common solid tumour in infancy but its aetiology is largely unknown. Prenatal factors might play a key role in its pathogenesis. Previous studies investigated whether birth weight is associated with risk of neuroblastoma, with conflictive results. We conducted a meta-analysis to quantitatively summarize the published evidence.

METHODS

Results from 10 case-control studies and one cohort study (1966 to December 2008) were included, involving a total of 3004 children with neuroblastoma. We constructed random-effects and fixed-effects models, performed 'pool-first' analyses, assessed heterogeneity and publication bias and performed sensitivity and influence analyses.

RESULTS

High birth weight (>4000 g) was associated with increased risk of neuroblastoma [odds ratio (OR) 1.19; 95% confidence interval (CI) 1.04-1.36]. Results for high birth weight were highly homogenous (I(2) = 0%). Low birth weight (<2500 g) was also related to increased risk of neuroblastoma (OR 1.24; 95% CI 1.0-1.55), but results were more heterogeneous (I(2 )= 30%). No evidence for particularly influential studies or for publication bias was found. However, sensitivity analysis indicated the presence of bias in studies on the association with low birth weight. Above 2500 g each 1000-g increase in birth weight was associated with a 13% (95% CI 3-25) increase in risk of neuroblastoma.

CONCLUSIONS

This meta-analysis shows that high birth weight is highly reproducibly associated with increased risk of neuroblastoma. The association with low birth weight was found to be less robust and deserves further studies.

Comparison of birth weight corrected for gestational age and birth weight alone in prediction of development of childhood leukemia and central nervous system tumors

INTRODUCTION

High birth weight (HBW) is an established risk factor for childhood acute lymphoblastic leukemia (ALL). The purpose of this study was to evaluate if birth weight (BW) corrected-for-gestational age is a better predictor than BW alone for occurrence of ALL and other malignancies in children.

MATERIALS AND METHODS

Birth certificate data of 2,254 children with cancer who were younger than 5 years old at diagnosis and registered at Texas Cancer Registry during 1995-2003 were compared to 11,734 age-matched controls. Multivariable logistic regression was used to compare models with BW corrected-for-gestational age and BW alone.

RESULTS

Compared to children who were appropriate for gestational age (AGA), children who were large for gestational age (LGA) at birth had a 1.66 times (95% CI 1.32-2.10) higher odds of ALL. Similarly, children with a BW > or =4,000 g had a 1.5 times (95% CI 1.18-1.89) higher odds for ALL, compared to children who weighed >2,500 and <4,000 g at birth. Using model diagnostics, the model containing BW corrected-for-gestational age was a better predictor than the model with BW alone [Akaike's Information Criterion (AIC) 4,646 vs. 4,658, respectively]. Odds ratios (OR) were similar for LGA children who were <4,000 g and LGA children who were > or =4,000 g (OR = 1.5, 95% CI 0.97-2.5 and OR = 1.67, 95% CI 1.29-2.16, respectively). BW was not an independent risk factor for acute myeloid leukemia or brain tumors.

CONCLUSION

BW corrected-for-gestational age is a better predictor than BW alone of risk for ALL. Future studies using BW variable should incorporate gestational age in their analyses.

Fetal growth and risk of childhood acute lymphoblastic leukemia: results from an Australian case-control study

The relation between intrauterine growth and risk of childhood acute lymphoblastic leukemia was investigated in an Australian population-based case-control study that included 347 cases and 762 controls aged <15 years recruited from 2003 to 2006. Information on proportion of optimal birth weight, a measure of the appropriateness of fetal growth, was collected from mothers by questionnaire. Data were analyzed by using logistic regression. Risk of acute lymphoblastic leukemia was positively associated with proportion of optimal birth weight; the odds ratio for a 1-standard-deviation increase in proportion of optimal birth weight was 1.18 (95% confidence interval: 1.04, 1.35) after adjustment for the matching variables and potential confounders. This association was also present among children who did not have a high birth weight, suggesting that accelerated growth, rather than high birth weight per se, is associated with risk of acute lymphoblastic leukemia. Similar associations between proportion of optimal birth weight and acute lymphoblastic leukemia were observed for both sexes and across age groups and leukemia subtypes. Results of this study confirm earlier findings of a positive association between rapidity of fetal growth and subsequent risk of acute lymphoblastic leukemia in childhood, and they are consistent with a role for insulin-like growth factors in the causal pathway.

The epidemiology of neuroblastoma: a review

Neuroblastoma is the most common tumour in children less than 1 year of age. The goal of this review was to summarise the existing epidemiological research on risk factors for neuroblastoma. A comprehensive search of the literature was undertaken using PubMed for epidemiological studies on neuroblastoma risk factors. We ascertained 47 articles which examined the risk factors. Ten studies employed population-based case-control designs; six were hospital-based case-control studies; two were cohort studies; and five employed ecological designs. Studies ranged in size from 42 to 538 cases. Three studies showed evidence of an increased risk of disease with use of alcohol during pregnancy (OR range 1.1, 12.0). Protective effects were seen with maternal vitamin intake during pregnancy (OR range 0.5, 0.7) in two studies, while risk of disease increased with maternal intake of diuretics (OR range 1.2, 5.8) in three studies. Three studies reported a decrease in risk for children with a history of allergic disease prior to neuroblastoma diagnosis (OR range 0.2, 0.4). The rarity of neuroblastoma makes this disease particularly challenging to study epidemiologically. We review the methodological limitations of prior research and make suggestions for further areas of study.

Fetal growth and the risk of childhood CNS tumors and lymphomas in Western Australia

The etiology of childhood cancers is largely unknown, although the early age at diagnosis has led to particular interest in in utero and perinatal factors. Birth weight is the most frequently studied perinatal factor in relation to risk of childhood cancers, and results have been inconsistent. We investigated whether the risk of CNS tumors and lymphomas in children was associated with three measures of the appropriateness of intra-uterine growth: proportion of optimal birth weight (POBW), birth length (POBL) and weight for length (POWFL). A cohort of 576,633 infants born in Western Australia in 1980-2004 were followed from birth to diagnosis of a CNS tumor (n = 183) or lymphoma (n = 84) before age 15, death, or December 31, 2005, and analyzed with Cox regression. Overall, there was little evidence of any association between fetal growth and risk of CNS tumors, although risk of ependymoma/choroid plexus tumors was positively associated with POBL and negatively associated with POWFL. The risk of Hodgkin and Burkitt lymphoma increased with increasing fetal growth among boys only, whereas the increased risk observed with non-Hodgkin lymphoma was only in girls. These associations between fetal growth and disease risk were also observed among children not classified as high birth weight, suggesting that accelerated growth is more important than birth weight per se. Results were similar when cases were compared with their unaffected siblings, suggesting that the increased growth associated with cancer risk was not general to the family. The associations we observed are consistent with causal pathways involving fetal growth factors.