Maternal and perinatal risk factors for Wilms' tumor: a nationwide nested case-control study in Sweden

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.

Prevalence and Perinatal Outcomes Following In Utero Exposure to Prehospital Emergency Methoxyflurane: A 17-Year Retrospective Cohort Study

OBJECTIVE

To examine the prevalence of exposure and perinatal outcomes associated with in utero exposure to methoxyflurane.

DESIGN, SETTING AND POPULATION

Whole-population ambulance data in Western Australia (WA) were linked to the statutory perinatal data collection to identify pregnant women transferred by ambulance between 2000 and 2016. The proportion of neonates in WA exposed to methoxyflurane, fentanyl or no analgesia during an ambulance transfer was calculated. Perinatal outcomes of pregnancies exposed to methoxyflurane (n=1579) were compared to those exposed to fentanyl (n=203) or no analgesia (n=10524) using multivariable logistic regression modelling. Perinatal outcomes were considered overall and by trimester of exposure.

MAIN OUTCOME MEASURES

Primary outcomes were the prevalence of in utero methoxyflurane exposure and Apgar score on the day of delivery.

RESULTS

In the study period, 0.4% of all neonates born in WA were exposed to methoxyflurane in utero. Methoxyflurane exposure on the day of delivery (n=657) was not associated with an increased likelihood of a low Apgar score at five minutes compared with no analgesia (n=2667) (OR 1.23, 95% CI 0.91-1.67). Whereas fentanyl exposure (n=22) was associated with an increased likelihood of low Apgar score compared with methoxyflurane (OR 3.67, 95% CI 1.18-11.48).

CONCLUSIONS

Methoxyflurane is commonly used by ambulance services to treat pain in pregnant women in WA. While not recommended for use in pregnancy, pregnancies exposed to methoxyflurane did not have an increased risk of adverse perinatal outcomes in this study.

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.

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.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Final height and IGF1 in adult survivors of Wilms tumour

OBJECTIVE

One-sided nephrectomy is followed by increased levels of IGF1, associated with linear growth during childhood. The aim was to evaluate final height and IGF1 levels in nephrectomized Wilms tumour survivors when compared with healthy Dutch references and survivors of other cancer types.

DESIGN

Cross-sectional retrospective study.

METHODS

Data of 575 adult childhood cancer survivors were analysed. median follow-up time was 17.8 (range 5.048.8) years. Analysis of (co)variance was performed to evaluate differences between subgroups: nephrectomized Wilms survivors treated with or without abdominal irradiation (n=41 and n=36) and survivors of other cancer types treated with or without irradiation involving the cranium, abdomen or total body (n=149 and n=349). Main outcome measures were IGF1 and height, expressed as SDS.

RESULTS

After adjustment for age at diagnosis, former corticosteroid treatment and renal impairment, height SDS in non-irradiated nephrectomized Wilms survivors was significantly higher than that in non-irradiated survivors of other cancer types (estimated mean SDS -0.09 vs -0.49, P=0.044), abdominal irradiated survivors (SDS -0.70, P=0.015) and other irradiated survivors (SDS -1.47, P<0.001). Non-irradiated nephrectomized Wilms tumour survivors had significantly higher IGF1 SDS than other irradiated survivors (estimated mean SDS -0.05 vs -1.36, P<0.001 and 0.11 vs 1.37, P<0.001), while there was no significant difference with the other two subgroups.

CONCLUSIONS

Adult survivors of Wilms tumour showed better attainment of final height and relatively higher IGF1 levels than those of other cancer types who had significantly shorter stature and lower IGF1 levels than Dutch references.

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.

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.

Review article: Efficacy and safety of methoxyflurane analgesia in the emergency department and prehospital setting

This article reviews the evidence for the analgesic efficacy of methoxyflurane in both prehospital and ED settings, as well as the adverse event profile associated with methoxyflurane use. Although there are no published controlled trials of methoxyflurane in sub-anaesthetic doses, available data indicate that it is an efficacious analgesic. There is inadequate evidence regarding its use as an agent for procedural pain. Despite the potential for renal impairment evident when it was used in anaesthetic doses, no significant adverse effects have been reported in the literature, neither in patients nor occupationally, when the dose used is limited to that currently recommended.

Obstetric history and birth characteristics and Wilms tumor: a report from the Children's Oncology Group

Previous epidemiologic studies have suggested that various pregnancy and birth characteristics may be associated with Wilms tumor, a childhood kidney tumor. We evaluated obstetric events and birth characteristics in relation to Wilms tumor using data from a large North American case-control study. Mothers of 521 children with Wilms tumor and 517 controls, frequency matched on child's age and geographic region, provided information about their labor and delivery history and their children's birth characteristics through a detailed computer-assisted telephone interviews. Most obstetric factors were not associated with Wilms tumor, but modest associations were observed for labor induction (OR: 1.4, 95% Confidence Interval (CI): 1.1, 1.8), prenatal vaginal infection (OR: 1.8, 95% CI: 1.2, 2.8), and upper respiratory infection (OR: 1.5, 95% CI: 1.0, 2.4). Low (<2500 g) and high (>4500 g) birth weight and preterm delivery (<37 weeks completed gestation) were associated with an elevated risk of Wilms tumor, as was neonatal respiratory problems. The association for high birth weight was present only among children with perilobar nephrogenic rests (OR: 2.1, 95% CI: 1.2, 3.9), possibly distinguishing a specific association among a biologically distinct subgroup of Wilms tumor cases. The results of this large study did not support many of the earlier findings of smaller studies. However, additional investigations of the effects of certain obstetric and birth characteristics among more refined tumor subgroups may further our understanding of these factors in relation to Wilms tumor.

Birth characteristics and Wilms tumor in Minnesota

Wilms tumor (WT) is a childhood kidney cancer with the highest rate of occurrence before the age of 2. Since it is rare, previous research has been limited and few risk factors have been established. We used a case-cohort design to examine the influence of birth characteristics on occurrence of WT in Minnesota. A total of 2,188 cases of cancer diagnosed in children aged 28 days to 14 years from 1988 to 2004 were identified using the Minnesota Cancer Surveillance System (MCSS). For each case, 4 children were randomly selected from Minnesota birth records during 1976-2004, frequency matched on birth year. Thus, a total of 8,752 children comprised the subcohort for the study, who in this analysis, served as comparison to the 138 cases of WT. Study variables included parental demographics, maternal pregnancy history and conditions and health and conditions of the child at birth. Associations with WT were assessed using hazard ratios (HR) and 95% confidence intervals (CI) calculated from stratified Cox regression models. We found an increased risk of WT for children who were large for gestational age compared to those average for gestational age and for children with congenital abnormalities. There was also an increased risk for children with a birth weight > 4,000 g compared to those with a birth weight between 2,500 and 4,000 g. All other factors examined showed no association with WT. This study contributes to the mounting evidence that children with large size at birth have an increased risk of WT.

Prenatal Multivitamin Supplementation and Rates of Pediatric Cancers: A Meta-Analysis

Prenatal supplementation of folic acid has been shown to decrease the risk of several congenital malformations. Several studies have recently suggested a potential protective effect of folic acid on certain pediatric cancers. The protective role of prenatal multivitamins has not been elucidated. We conducted a systematic review and meta-analysis to assess the potential protective effect of prenatal multivitamins on several pediatric cancers. Medline, PubMed, EMBASE, Toxline, Healthstar, and Cochrane databases were searched for studies published in all languages from 1960 to July 2005 on multivitamin supplementation and pediatric cancers. References from all articles collected were reviewed for additional articles. Two blinded independent reviewers assessed the articles for inclusion and exclusion. Rates of cancers in women supplemented with multivitamins were compared with unsupplemented women using a random effects model. Sixty-one articles were identified in the initial search, of which, seven articles met the inclusion criteria. There was an apparent protective effect for leukemia (odds ratio (OR)=0.61, 95% confidence interval (CI)=0.50-0.74), pediatric brain tumors (OR=0.73, 95% CI=0.60-0.88) and neuroblastoma (OR=0.53, 95% CI=0.42-0.68). In conclusion, maternal ingestion of prenatal multivitamins is associated with a decreased risk for pediatric brain tumors, neuroblastoma, and leukemia. Presently, it is not known which constituent(s) among the multivitamins confer this protective effect.

Parental age and risk of childhood cancers: a population-based cohort study from Sweden

BACKGROUND

Frequent germ line cells mutations were previously demonstrated to be associated with aging. This suggests a higher incidence of childhood cancer among children of older parents. A population-based cohort study of parental ages and other prenatal risk factors for five main childhood cancers was performed with the use of a linkage between several national-based registries.

METHODS

In total, about 4.3 million children with their parents, born between 1961 and 2000, were included in the study. Multivariate Poisson regression was used to obtain the incidence rate ratios (IRR) and 95% confidence interval (CI). Children <5 years of age and children 5-14 years of age were analysed independently.

RESULTS

There was no significant result for children 5-14 years of age. For children <5 years of age, maternal age were associated with elevated risk of retinoblastoma (oldest age group's IRR = 2.39, 95%CI = 1.17-4.85) and leukaemia (oldest age group's IRR = 1.44, 95%CI = 1.01-2.05). Paternal age was significantly associated with leukaemia (oldest age group's IRR = 1.31, 95%CI = 1.04-1.66). For central nervous system cancer, the effect of paternal age was found to be significant (oldest age group's IRR = 1.69, 95%CI = 1.21-2.35) when maternal age was included in the analysis.

CONCLUSION

Our findings indicate that advanced parental age might be associated with an increased risk of early childhood cancers.

Wilms’ tumor and exposures to residential and occupational hazardous chemicals

This case-control study examines the association between residential and occupational exposures to hazardous chemicals and the risk of Wilms' tumor. The study included 303 cases recruited from six state cancer registries, who were diagnosed between January 1, 1992 and December 31, 1995. A total of 575 controls selected through random digit dialing were frequency matched to the cases. A standard questionnaire was administered to participants during a telephone interview. Parental residential addresses and locations of US Environmental Protection Agency National Priority List (NPL) sites were geocoded and analyzed, along with occupational exposure information. There were no cases of Wilms' tumor found in individuals living within one-half mile distance of a hazardous waste site. However, elevated odds ratios were found for using hairdressing chemicals, motor oil, paint, paint stripper, and pesticides during the pregnancy term and during the 2-year period prior to birth. The findings do not support the hypothesis that Wilms' tumor is associated with residing near an NPL site.

Nongenetic causes of childhood cancers: evidence from international variation, time trends, and risk factor studies

Ionizing radiation and a variety of genetic conditions are thought to explain 5-10% of childhood cancers. Infection with Epstein-Barr virus (EBV) in parts of Africa and human immunodeficiency virus (HIV) increase the risk of Burkitt's lymphoma and Kaposi's sarcoma, respectively. Other risk factors have not been conclusively identified. A review of the data on international variation in incidence, recent changes in incidence, and risk factors suggests that many childhood cancers are likely to have nongenetic causes. The pattern of international variation and associations with surrogates of infection suggest an infectious etiology for acute lymphoblastic leukemia, although no agent has been identified. The biologic plausibility is strong that maternal consumption of food containing DNA topoisomerase II inhibitors may increase the risk of acute myeloid leukemia, although the data are limited now. For brain tumors, cured meats, polyomaviruses, and farm exposures may have etiologic roles. Changes in the incidence and characteristics of children with hepatoblastoma as well as risk factor studies suggest a role for an exposure of very low birth weight babies. High birth weight, tea or coffee consumption, and certain paternal occupations have shown some consistency in their association with Wilms' tumor. For most of the other cancers, very few epidemiologic studies have been conducted, so it is not surprising that nongenetic risk factors have not been detected. The most important difference between the cancers for which there are good etiologic clues and those for which there are not may be the number of relevant studies.

A registry-based study of gender, fetal growth, and risk of Wilms tumor

The possibility of an interaction between gender and fetal growth on the risk of Wilms tumor is poorly examined. Using nationwide population-based registries, the authors identified all children (N = 126) diagnosed with Wilms tumor in Denmark, 1973-1993, and selected 10 matched population controls per case. Data on birth weight, gestational age, and ponderal index were used to examine the association between gender, fetal growth, and risk of Wilms tumor. It was found that the risk of Wilms tumor increased with fetal growth in girls, but decreased with fetal growth in boys, although the findings did not reach statistical significance.

Association of pregnancy history and birth characteristics with neuroblastoma: a report from the Children's Cancer Group and the Pediatric Oncology Group

Previous studies have suggested a relationship between reproductive history, pregnancy and birth factors, and the risk of neuroblastoma. We conducted a case-control telephone interview study that included a total of 504 children under the age of 19 years with newly diagnosed neuroblastoma identified by two national collaborative clinical trials groups, the Children's Cancer Group and the Pediatric Oncology Group. A total of 504 controls, matched to cases on age, were identified by random digit dialing. Conditional logistic regression was used to estimate the matched odds ratio (OR) and 95% confidence interval (CI) with adjustment for household income, and maternal race and education. In addition, case subgroups defined by age at diagnosis, tumour MYCN oncogene amplification status, and stage were evaluated. A suggestive pattern of increased risk was seen for a greater number of prior pregnancies, history of previous miscarriages and induced abortions, with nearly a twofold increase in risk for two or more prior induced abortions (OR = 1.9, 95% CI [1.0,3.7]). No association was found for the following diseases or conditions during pregnancy: hepatitis, rubella, measles, mumps, chickenpox, mononucleosis, vaccinations, morning sickness, pre-eclampsia, bleeding, proteinuria, anaemia, urinary tract infections, heart disease, kidney disease, liver disease and diabetes. A weak association was found for hypertension during pregnancy. Several labour and delivery factors were related to an increased risk, including threatened miscarriage, anaesthetic during labour (specifically epidural) and caesarean delivery. We found associations between premature delivery (<33 weeks: OR = 1.9, 95% CI [0.7,4.8]), very low birthweight (<1500 g: OR = 2.6, 95% CI [0.7,10.3]) and risk of neuroblastoma. There was no consistent pattern of increased risk found for most factors within subgroups defined by age at diagnosis, stage or MYCN status.

Hoxa9 transforms primary bone marrow cells through specific collaboration with Meis1a but not Pbx1b

Hoxa9, Meis1 and Pbx1 encode homeodomaincontaining proteins implicated in leukemic transformation in both mice and humans. Hoxa9, Meis1 and Pbx1 proteins have been shown to physically interact with each other, as Hoxa9 cooperatively binds consensus DNA sequences with Meis1 and with Pbx1, while Meis1 and Pbx1 form heterodimers in both the presence and absence of DNA. In this study, we sought to determine if Hoxa9 could transform hemopoietic cells in collaboration with either Pbx1 or Meis1. Primary bone marrow cells, retrovirally engineered to overexpress Hoxa9 and Meis1a simultaneously, induced growth factor-dependent oligoclonal acute myeloid leukemia in <3 months when transplanted into syngenic mice. In contrast, overexpression of Hoxa9, Meis1a or Pbx1b alone, or the combination of Hoxa9 and Pbx1b failed to transform these cells acutely within 6 months post-transplantation. Similar results were obtained when FDC-P1 cells, engineered to overexpress these genes, were transplanted to syngenic recipients. Thus, these studies demonstrate a selective collaboration between a member of the Hox family and one of its DNA-binding partners in transformation of hemopoietic cells.

High birth weight and risk of specific childhood cancers: a report from the Children's Cancer Group

OBJECTIVES

High birth weight has been associated with a number of childhood cancers. This study was conducted to test the hypothesis that elevated birth weight is associated with an increased risk of diagnosis-specific and age-specific groups of childhood cancers.

METHODS

A case-control study, using a large Children's Cancer Group database, examined birth weight as a risk factor for childhood cancer. Birth weight information for the index child was available for 3711 cases and 816 control subjects.

RESULTS

There was a statistically significant increased risk of acute lymphoblastic leukemia, Wilms' tumor, and neuroblastoma with increasing birth weight (p, trend = 0.006, 0.003, and 0.001, respectively). A statistically significant decreased risk of cancer was observed for soft tissue sarcoma (p, trend = 0.04). When data were stratified on the basis of age at diagnosis, many of these associations were apparent for children whose disease was diagnosed before the age of 2 years. Moreover, for acute myeloid leukemia, age at diagnosis was an important effect modifier. For children with acute myeloid leukemia whose disease was diagnosed before 2 years of age, there was a statistically significant increased risk with high birth weight (odds ratio = 2.5, 95% confidence interval 1.1 to 5.5); there was no increased risk of acute myeloid leukemia with high birth weight noted for children whose disease was diagnosed after 2 years of age (odds ratio 1.3, 95% confidence interval 0.8 to 2.2).

CONCLUSIONS

Biologic studies are needed to address why high birth weight may increase risk (particularly at younger ages) of development of certain cancers.

Wilms' tumor

Wilms' tumor is the most common renal malignancy of childhood. Survival rates for favorable histology of Wilms' tumor currently approach 90%. Recent advances in the molecular genetics of Wilms' tumor have led to insights into the genetic factors involved in the development of Wilms' tumor, normal renal development, and the mechanisms of tumorigenesis.

Birth characteristics and risk of Wilms' tumour: a nationwide prospective study in Norway

Relationships between incidence of Wilms' tumour and information recorded at birth were investigated in a prospective study of the 1,489,297 children born in Norway between 1967 and 1992. A total of 119 individuals were diagnosed with Wilms' tumour in the age interval 0-14 years. A high length at birth was significantly associated with a high risk (incidence rate ratio 1.8 for length > or = 53 cm vs < or = 49 cm, 95% CI 1.0-3.2). A low Apgar score at 1 min was also associated with an increased risk (incidence rate ratio 2.2 for Apgar score < or = 8 vs a score > or = 9, 95% CI 1.2-3.9). For all variables for which an association was indicated, the association seemed to be restricted mainly to children aged less than 2 years. This suggests that Wilms' tumour diagnosed early in life may differ aetiologically from that of cases diagnosed later.