Prenatal epidemiology of pediatric tumors

Neonatal Cancer Epidemiology and Outcome: A Retrospective Study

OBJECTIVE

Our study aimed at describing neonatal cancer incidence, distribution by type, location, outcome, and long-term toxicity, by comparison with tumors occurring later in infancy.

METHODS

The authors led a single-center retrospective analysis of 118 cases of tumors diagnosed in the first year of life and compared tumors' types incidence, presentation, location, and outcome according to age group at diagnosis (below or over 28 d of life).

RESULTS

The most frequent neonatal tumor types in our series were germ cell tumors, mainly teratoma, followed by neuroblastoma and renal tumors, whereas in children below 1 year of age, brain tumors, neuroblastoma, and leukemia were the most common types. Genetic predisposition syndromes were present in 14% of these infants and antenatal sonography enabled 68% of diagnosis for tumors presenting at birth. Other patients presented with mass syndrome, hydrops, or skin lesions. Six percent of neonates with cancer died from their malignancies, and up to 18% experienced a chronic health condition as a consequence of therapy.

CONCLUSIONS

Tumor pattern differs in neonates and infants, with a higher percentage of benign tumors in children below 28 days of life. Yet, long-term therapy-related toxicity is significant in younger patients. Enhancing knowledge of neonatal tumors, their epidemiology, clinical presentation, genetic background, and prognosis should help promote better management and introduce follow-up programs to improve surviving rates and the quality of life of survivors.

Childhood cancer incidence in Canada: demographic and geographic variation of temporal trends (1992-2010)

INTRODUCTION

Surveillance of childhood cancer incidence trends can inform etiologic research, policy and programs. This study presents the first population-based report on demographic and geographic variations in incidence trends of detailed pediatric diagnostic groups in Canada.

METHODS

The Canadian Cancer Registry data were used to calculate annual age-standardized incidence rates (ASIRs) from 1992 to 2010 among children less than 15 years of age by sex, age and region for the 12 main diagnostic groups and selected subgroups of the International Classification of Childhood Cancer (ICCC), 3rd edition. Temporal trends were examined by annual percent changes (APCs) using Joinpoint regression.

RESULTS

The ASIRs of childhood cancer among males increased by 0.5% (95% confidence interval (CI) = 0.2-0.9) annually from 1992 to 2010, whereas incidence among females increased by 3.2% (CI = 0.4-6.2) annually since 2004 after an initial stabilization. The largest overall increase was observed in children aged 1-4 years (APC = 0.9%, CI = 0.4-1.3). By region, the overall rates increased the most in Ontario from 2006 to 2010 (APC = 5.9%, CI = 1.9-10.1), and increased non-significantly in the other regions from 1992 to 2010. Average annual ASIRs for all cancers combined from 2006 to 2010 were lower in the Prairies (149.4 per million) and higher in Ontario (170.1 per million). The ASIRs increased for leukemias, melanoma, carcinoma, thyroid cancer, ependymomas and hepatoblastoma for all ages, and neuroblastoma in 1-4 year olds. Astrocytoma decreased in 10-14 year olds (APC = -2.1%, CI = -3.7 to -0.5), and among males (APC = -2.4%, CI = -4.6 to -0.2) and females (APC = -3.7%, CI = -5.8 to -1.6) in Ontario over the study period.

CONCLUSION

Increasing incidence trends for all cancers and selected malignancies are consistent with those reported in other developed countries, and may reflect the changes in demographics and etiological exposures, and artefacts of changes in cancer coding, diagnosis and reporting. Significant decreasing trend for astrocytoma in late childhood was observed for the first time.

Residential proximity to environmental pollution sources and risk of rare tumors in children

BACKGROUND

Few epidemiologic studies have explored risk factors for rare tumors in children, and the role of environmental factors needs to be assessed.

OBJECTIVES

To ascertain the effect of residential proximity to both industrial and urban areas on childhood cancer risk, taking industrial groups into account.

METHODS

We conducted a population-based case-control study of five childhood cancers in Spain (retinoblastoma, hepatic tumors, soft tissue sarcomas, germ cell tumors, and other epithelial neoplasms/melanomas), including 557 incident cases from the Spanish Registry of Childhood Tumors (period 1996-2011), and 3342 controls individually matched by year of birth, sex, and region of residence. Distances were computed from the residences to the 1271 industries and the 30 urban areas with ≥75,000 inhabitants located in the study area. Using logistic regression, odds ratios (ORs) and 95% confidence intervals (95%CIs) for categories of distance to industrial and urban pollution sources were calculated, with adjustment for matching variables and socioeconomic confounders.

RESULTS

Children living near industrial and urban areas as a whole showed no excess risk for any of the tumors analyzed. However, isolated statistical associations (OR; 95%CI) were found between retinoblastoma and proximity to industries involved in glass and mineral fibers (2.49; 1.01-6.12 at 3km) and organic chemical industries (2.54; 1.10-5.90 at 2km). Moreover, soft tissue sarcomas registered the lower risks in the environs of industries as a whole (0.59; 0.38-0.93 at 4km).

CONCLUSIONS

We have found isolated statistical associations between retinoblastoma and proximity to industries involved in glass and mineral fibers and organic chemical industries.

Birth Characteristics and Childhood Leukemia Risk: Correlations With Genetic Markers

Birth characteristics such as birth order, birth weight, birth defects, and Down syndrome showed some of the first risk associations with childhood leukemia. Examinations of correlations between birth characteristics and leukemia risk markers have been limited to birth weight-related genetic polymorphisms. We integrated information on nongenetic and genetic markers by evaluating the relationship of birth characteristics, genetic markers for childhood acute lymphoblastic leukemia (ALL) susceptibility, and ALL risk together. The multiethnic study consisted of cases with childhood ALL (n=161) and healthy controls (n=261). Birth characteristic data were collected through questionnaires, and genotyping was achieved by TaqMan SNP Genotyping Assays. We observed risk associations for birth weight over 4000 g (odds ratios [OR]=1.93; 95% confidence interval [CI], 1.16-3.19), birth length (OR=1.18 per inch; 95% CI, 1.01-1.38), and with gestational age (OR=1.10 per week; 95% CI, 1.00-1.21). Only the HFE tag single-nucleotide polymorphism (SNP) rs9366637 showed an inverse correlation with a birth characteristic, gestational age, with a gene-dosage effect (P=0.005), and in interaction with a transferrin receptor rs3817672 genotype (Pinteraction=0.05). This correlation translated into a strong association for rs9366637 with preterm birth (OR=5.0; 95% CI, 1.19-20.9). Our study provides evidence for the involvement of prenatal events in the development of childhood ALL. The inverse correlation of rs9366637 with gestational age has implications on the design of HFE association studies in birth weight and childhood conditions using full-term newborns as controls.

Spatial analysis of childhood cancer: a case/control study

Background

Childhood cancer was the leading cause of death among children aged 1-14 years for 2012 in Spain. Leukemia has the highest incidence, followed by tumors of the central nervous system (CNS) and lymphomas (Hodgkin lymphoma, HL, and Non-Hodgkin’s lymphoma, NHL). Spatial distribution of childhood cancer cases has been under concern with the aim of identifying potential risk factors.

Objective

The two objectives are to study overall spatial clustering and cluster detection of cases of the three main childhood cancer causes, looking to increase etiological knowledge.

Methods

We ran a case-control study. The cases were children aged 0 to 14 diagnosed with leukemia, lymphomas (HL and NHL) or CNS neoplasm in five Spanish regions for the period 1996-2011. As a control group, we used a sample from the Birth Registry matching every case by year of birth, autonomous region of residence and sex with six controls. We geocoded and validated the address of the cases and controls. For our two objectives we used two different methodologies. For the first, for overall spatial clustering detection, we used the differences of K functions from the spatial point patterns perspective proposed by Diggle and Chetwynd and the second, for cluster detection, we used the spatial scan statistic proposed by Kulldorff with a level for statistical significance of 0.05.

Results

We had 1062 cases of leukemia, 714 cases of CNS, 92 of HL and 246 of NHL. Accordingly we had 6 times the number of controls, 6372 controls for leukemia, 4284 controls for CNS, 552 controls for HL and 1476 controls for NHL. We found variations in the estimated empirical D(s) for the different regions and cancers, including some overall spatial clustering for specific regions and distances. We did not find statistically significant clusters.

Conclusions

The variations in the estimated empirical D(s) for the different regions and cancers could be partially explained by the differences in the spatial distribution of the population; however, according to the literature, we cannot discard environmental hazards or infections agents in the etiology of these cancers.

Molecular Epidemiology, prenatal exposure and prevention of cancer

Molecular Epidemiology was originally conceived as a preventive approach, providing a valuable tool for investigating risk factors for cancer in vulnerable populations. Biomarkers can be used as early indicators of risk for preventative purposes and risk assessment. The present contribution mainly refers to in utero exposures to carcinogens, since humans are especially vulnerable during fetal development. Environmental exposures in utero can increase risks for both childhood and adult cancers; their interactions with genetic and nutritional susceptibility factors may further increase risk. Thus, the early developmental period represents an important window for cancer prevention.

Health outcomes among infants born to women deployed to United States military operations during pregnancy

BACKGROUND

Military professionals who deploy to combat operations may encounter hazards that could adversely affect reproductive health. Pregnant women are generally exempt from deployment to military operations; however, exposures to such environments may inadvertently occur. We investigated whether maternal deployment during pregnancy was associated with adverse health outcomes in infants.

METHODS

The United States Department of Defense Birth and Infant Health Registry identified infants born to military service women between 2002 and 2005, and defined their health outcomes at birth and in the first year of life. Multivariable modeling was applied to investigate preterm birth and birth defects among infants, based on maternal deployment experience during pregnancy.

RESULTS

Among 63,056 infants born to military women from 2002 to 2005, 22,596 were born to women with deployment experience in support of the current military operations before, during, or after their pregnancy. These included 2941 infants born to women who appeared to have been deployed some time during their first trimester of pregnancy. Compared to infants born to women who deployed at other times, or never deployed, exposed infants were not more likely to be born preterm, diagnosed with a major birth defect, or diagnosed with a malignancy.

CONCLUSIONS

In this exploratory analysis, infants born to women who inadvertently deployed to military operations during their pregnancy were not at increased risk of adverse birth or infant health outcomes. Future analyses should examine outcomes related to specific maternal exposures during deployment, and outcomes among the growing number of infants conceived after deployment.

[Risks factors for pediatric malignant liver tumors]

OBJECTIVE

Pediatric Hepatic Malignancies (PHMs) are the result of the interaction between constitutional and environmental risk factors (RFs). We review the evidence on the main RFs associated to PHMs.

METHOD

Systematic review of the literature published in the last 25 years on Medline, Embase, Cancerlit, Lilacs and SciElo using the following key words: "etiology/risk factor/epidemiology" and "malignant liver tumors/hepatic cancer" or "hepatoblastoma/hepatocarcionoma".

RESULTS

PHMs account for 1 % of all pediatric malignancies. The main types, hepatoblastoma (HB) and hepatocarcionma (HCC) make up 98-99 % of PHM. The main constitutional RFs are: a) Beckwith-Wiedemann (BW) syndrome; b) isolated hemihyperplasia syndrome (IHS); c) adenomatous polyps of the colon; d) hemochromatosis; e) Hereditary Tyrosinemia Type 1; f) a -1-antitrypsin deficiency; g) porphyrias; h) cirrhosis; i) nonalcoholic steatosis; and j) primary sclerosing cholangitis. The main environmental RFs are: a) hepatitis B virus (HBV) and C virus (HCV); b) B1 aflatoxin (B1AF); c) ionizing radiation; d) alcohol; e) hormonal treatments; f) occupational exposure to pesticides, solvents, vinyl chloride and metals; g) smoking; h) arsenic; i) prematury and very low birth weight; and j) trematodes.

CONCLUSIONS

The clinical, analytical and ultrasound screening facilitate the early diagnosis of HB in the previously mentioned genetic syndromes, particularly BW and IHS during the first years of life. HBV universal vaccination of newborns provides the biggest opportunity to prevent a substantial proportion of PHMs. Also systematic monitoring of HBV and HCV in blood, hemoderivates, donated organs and drug addicts, are very useful. Other effective measures are: the reduction/elimination of B(1)AF in food, zero alcohol intake during childhood and adolescence as well decreasing prenatal exposure to the tobacco, solvents, pesticides, vinyl chloride, metals, ionizing radiation and hormonal treatments.

[Neonatal tumours and congenital malformations]

INTRODUCTION

The association between pediatric cancer and congenital abnormalities is well known but, there is no exclusive data on the neonatal period and the underlying etiopathogenic mechanisms are unknown.

OBJECTIVES

First, to analyze the frequency of neonatal tumours associated with congenital abnormalities; and second, to comment on the likely etiopathogenic hypotheses of a relationship between neonatal tumours and congenital abnormalities.

MATERIALS AND METHOD

Historical series of neonatal tumours from La Fe University Children's Hospital in Valencia (Spain), from January 1990 to December 1999. Histological varieties of neonatal tumours and associated congenital abnormalities were described. A systematic review of the last 25 years was carried out using Medline, Cancerlit, Index Citation Science and Embase. The search profile used was the combination of "neonatal/congenital-tumors/cancer/neoplasms" and "congenital malformations/birth defects".

RESULTS

72 neonatal tumours were identified (2.8% of all pediatric cancers diagnosed in our hospital) and in 15 cases (20.8%) there was some associated malformation, disease or syndrome. The association between congenital abnormalities and neonatal tumours were: a) angiomas in three patients: two patients with congenital heart disease with a choanal stenosis, laryngomalacia; b) neuroblastomas in two patients: horseshoe kidney with vertebral anomalies and other with congenital heart disease; c) teratomas in two patients: one with cleft palate with vertebral anomalies and other with metatarsal varus; d) one tumour of the central nervous system with Bochdaleck hernia; e) heart tumours in four patients with tuberous sclerosis; f) acute leukaemia in one patient with Down syndrome and congenital heart disease; g) kidney tumour in one case with triventricular hydrocephaly, and h) adrenocortical tumour: hemihypertrophy. The publications included the tumours diagnosed in different pediatric periods and without unified criteria to classify the congenital abnormalities. Little data exist on the neonatal period and the majority are from medical institutions registers. The prevalence varies from 15 to 31.6%. To explain this association, the hypotheses are based on prenatal exposures (preconceptional and transplacental exposure), to mutagenic and carcinogenic risk factors.

CONCLUSIONS

Neonatal tumours are more often associated to congenital abnormalities than other pediatric cancers. The inclusion and classification criteria needs to be unified to better understand the association between the neonatal tumours and congenital abnormalities. The environmental history in all neonatal tumours associated to congenital abnormalities, including the constitutional and environmental risk factors, will help to improve our knowledge of the underlying prenatal mechanisms and to an advance in its prevention.

Medication use during pregnancy and the risk of childhood cancer in the offspring

The young age at onset of many cancers in childhood has led to investigations on maternal exposures during pregnancy. Data from a population-based case-control study in Germany (1992-1997) that included 1,867 cases and 2,057 controls was used to investigate this question. Maternal use of vitamin, folate or iron supplementation was associated with a reduced risk of non-Hodgkin lymphoma and tumors and, less clearly, with leukemia, but not with CNS tumors. An increased risk of neuroblastoma was associated most markedly with diuretics and other antihypertensives, but also with vitamin, folate or iron supplementation. No associations were seen with pain relievers, antinauseants or cold medications, nor with delivery by Caesarian section. The strengths of this study are its population base, the large number of cases and the inclusion of different case groups to identify disease specificity of associations. The limitation of this study is an exposure assessment relying on maternal self-reports. In conclusion, these data indicate a potential influence of some maternal medication during pregnancy on the risk of childhood cancer in the offspring; however, no clear picture is seen.

Children as a sensitive subpopulation for the risk assessment process

For cancer risk assessment purposes, it is necessary to consider how to incorporate sensitive subpopulations into the process to ensure that they are appropriately protected. Children represent one such potentially sensitive subpopulation that is of quite considerable magnitude. The data needs include sensitivity to the induction of childhood cancers compared to adult cancers and relative sensitivity of early-life exposures for the formation of tumors in adults. These needs as far as human data are concerned are best met for ionizing radiations, for which it has been shown in the atomic bomb survivors that early-life exposures are more effective at inducing cancers later in life. The risk assessment approach for ionizing radiations, however, is based on tumor data itself for total population exposures so that there is no requirement to consider specifically the impact of early-life exposures. In the case of environmental chemicals, the majority of the tumor data used for risk assessments are from rodent bioassays. There is a paucity of data that allow for a comparison of the response to early-life exposures compared to that for adult-only exposures. This presents a fairly difficult challenge to the identification of a general sensitivity factor or a chemical-specific sensitivity factor for early-life exposures. The U.S. Environmental Protection Agency (EPA) has not, until recently, incorporated a general adjustment for early-life exposure to carcinogens into its risk assessment guidelines. The Agency has relied on the fact that, in the absence of specific data to the contrary, the linear extrapolation for rodent tumor data provided appropriate protection. When specific data are available, then an adjustment can be calculated. In its most recent draft guidelines, however, a general adjustment has been proposed for mutagenic chemicals. A 10-fold risk adjustment is recommended for the first 2 years of life, a 3-fold adjustment for years 3-15, and no adjustment for exposures after age 15. For chemicals that do not have a mutagenic mode of action, no adjustment is recommended because the data for deriving such an adjustment are simply not available. Clearly, this is an interim position that is dependent on more pertinent data being collected. A significant component of this is to conduct cancer bioassays that include early-life exposures.