Longer breast-feeding and protection against childhood leukaemia and lymphomas

Breastfeeding Beyond Six Months: Evidence of Child Health Benefits

Breastfeeding is globally recognized as the optimal method of infant nutrition, offering health benefits for both the child and the mother, making it a public health priority. However, the potential advantages of breastfeeding extend well beyond initial months. Breast milk adapts to the evolving needs of the growing infant, and its immunological, microbiological, and biochemical properties have been associated with enhanced protection against infections and chronic diseases, improved growth and development, and lower rates of hospitalization and mortality. This review explores the evidence supporting the continuation of breastfeeding beyond six months. More meticulous studies employing consistent methodologies and addressing confounders are essential. This will enable a more accurate determination of the extent and mechanisms of the positive impact of prolonged breastfeeding and allow for the implementation of effective public health strategies.

Breastfeeding Duration Reduces the Risk of Childhood Leukemia and Modifies the Risk of Developing Functional Gastrointestinal Disorders

Objective: The aim of this study was to test the hypothesis that the duration of breastfeeding in infancy reduces the risk of childhood leukemia or lymphoma, and modifies the risk of developing functional gastrointestinal disorders (FGIDs). Subjects and Methods: This case-control study involved the recruitment of children with lymphoid malignancy and functional gastrointestinal symptoms with healthy children as controls. Focused questionnaires were used to collect data on breastfeeding history and other key risk factors. Univariate and multivariate analyses were undertaken. Results: Of the 334 children with lymphoid malignancy, 65% were male. The control group included 334 age- and sex-matched participants. Most (n = 189; 56.6%) of the children with leukemia were <10 years of age. Differences between cases and controls included the duration of breastfeeding (p < 0.0001), mean birthweight (p < 0.001), maternal age (p < 0.001), paternal age (p < 0.001), birth order (p < 0.001), mean number of children (p < 0.001), BMI percentile (p = 0.042), and maternal smoking (p = 0.012). Breastfeeding duration of up to 6 months' duration, when compared with feeding of longer than 6 months, was associated with increased odds ratios (OR) for acute lymphoblastic leukemia (OR = 3.43, 95% confidence interval [CI] 2.37-4.98; p < 0.001), Hodgkin's lymphoma (OR = 1.58, 95% CI: 0.88-2.84, p = 0.120), Non-Hodgkin's lymphoma (OR = 2.14, 95% CI: 1.25-3.65, p = 0.005), and overall (OR = 1.95, 95% CI: 1.40-2.71, p < 0.001). Cases also differed from controls with regard to FGIDs, such as stomach ache (p < 0.001), dyspepsia (p < 0.001), early satiety (p = 0.017), bowel satisfaction (p < 0.001), bloating (p < 0.001), nausea (p = 0.005), vomiting (p = 0.039), constipation (p = 0.003), diarrhea (p = 0.010), gastrointestinal canal congestion (p =0.039), muscle aches pains (p = 0.008), fecal incontinence (p = 0.021), and indigestion (p = 0.003). A multivariate stepwise regression analysis revealed that maternal smoking (p < 0.001), formula feeding (p < 0.001), duration of breastfeeding (p < 0.001), birth order (p = 0.002), mother's age (p = 0.004) and the child's birthweight (p = 0.009) were predictors for leukemia. Further analysis showed that dyspepsia (p < 0.001), gastrointestinal tract canal congestion (p < 0.001), constipation (p = 0.009), diarrhea (p = 0.013), bowel satisfaction (p = 0.021), bloating (p = 0.022), duration of breastfeeding (p < 0.001), and stomach ache (p = 0.025) were significant predictors for developing FGID symptoms after adjusting for age, gender, and other confounding variables. Conclusion: This study confirmed that breastfeeding has some effect on reducing possible risk of childhood lymphoma and leukemia and FGID symptoms compared with healthy control children.

Selection of a suitable animal model to evaluate secretion of drugs in the human milk: a systematic approach

Lack of data on drug secretion in human milk is a concern for safe use of drugs during postpartum.Clinical studies are often difficult to perform; despite substantial improvements in computational methodologies such as physiologically based pharmacokinetic modelling, there is limited clinical data to validate such models for many drugs.Various factors that are likely to impact milk to plasma ratio were identified. A literature search was performed to gather available data on milk composition, total volume of milk produced per day, milk pH, haematocrit, and renal blood flow and glomerular filtration rate in various animal models.BLAST nucleotide and protein tools were used to evaluate the similarities between humans and animals in the expression and predominance of selected drug transporters, metabolic enzymes, and blood proteins.A multistep analysis of all the potential variables affecting drug secretion was considered to identify most appropriate animal model. The practicality of using the animal in a lab setting was also considered.Donkeys and goats were identified as the most suitable animals for studying drug secretion in milk and future studies should be performed in goats and donkeys to validate the preliminary observations.

Early Life Nutrition Factors and Risk of Acute Leukemia in Children: Systematic Review and Meta-Analysis

Acute leukemia commonly occurs in young children with peak incidence at the age of 2-5 years. However, the etiology is still unclear and many preventable risk factors still deserve to be reviewed. The focus of this systematic review and meta-analysis is to summarize the evidence concerning early life nourishment (breastfeeding, early life diet), neonatal vitamin K administration and the risk of acute leukemia. All epidemiological studies published up to June 2023 and assessing diet-related risk factors for childhood acute leukemia were identified in two electronic databases (PubMed and Web of Science), with no limits on publication year or language. A total of 38 studies (37 case-control studies and 1 study with pooled analysis) were included. The published risk estimates were combined into a meta-analysis using the Generic Inverse Variance method. The current evidence shows that breastfeeding (yes vs. no) has a protective effect against acute lymphoblastic leukemia (odds ratio = 0.85; 95% CI, 0.76-0.94). Evidence related to the role of other studied factors (foods and supplements) is inconclusive. Further research into the potential role of diet in early life and the risk of acute leukemia is needed to develop prevention strategies at population level. Review Registration: PROSPERO registration no. CRD42019128937.

Association between maternal breastfeeding and risk of systemic neoplasms of offspring

Background

Breastfeeding might prevent childhood cancer by stimulating the immune system.

Methods

The following databases, including PubMed, Embase, and Cochrane Library, were searched from inception to January 10, 2021.

Results

In dose-dependent manner, there was a statistically significant inverse association between any breastfeeding and the incidence of childhood cancer. There was no evidence that breastfeeding was inversely related to childhood cancer of the skeletal, reproductive, or sensory systems. However, breastfeeding was inversely associated with the incidence of hematological malignancies and cancers of the nervous and urinary systems. Among hematological malignancies, the relationship was significant for acute lymphocytic leukemia (ALL) and acute myeloid leukemia (AML), but not for acute non-lymphocytic leukemia (ANLL), Hodgkin’s lymphoma (HL), or non-HL.

Conclusions

The evidences demonstrated that breastfeeding have a potential protective role in preventing selective childhood cancer growth, especially for ALL, AML, cancer of nervous and urinary systems. This study recommended that breastfeeding be extended for as long as possible or maintained for at least 6 months to prevent selective childhood cancer growth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13052-022-01292-9.

COVID-19 and breastfeeding: can SARS-CoV-2 be spread through lactation?

SARS-CoV-2 is a new betacoronavirus that was first reported in the Hubei province, China, in December 2019. The virus is likely transmitted through air droplets. However, there are reported cases where SARS-CoV-2-RNA was found in other samples, such as blood or stool. Nonetheless, there is limited information concerning the presence of viral RNA in pregnancy-related samples, specifically breast milk. However unlikely, there is still uncertainty regarding the possibility of vertical transmission from mother to infant through breastfeeding. This review aims to synthetize the literature written so far on this topic. Despite not being extensively researched, vertical transmission through breast milk seems unlikely. Case series showed that milk samples from mothers with COVID-19 were almost entirely negative. So far, there have been only 9 recorded cases of viral shedding in milk samples, uncertain however of the viability of the particles. Furthermore, WHO and UNICEF strongly encourage commencing breastfeeding after parturition, underlining the benefits of lactation. Moreover, some studies have proven the existence of IgG and IgA anti-SARS-CoV-2-antibodies in the maternal milk that could possibly play an important part in the neonate’s protection against the virus. Vertical transmission through lactation seems unlikely, most studies pointing towards the safety of breastfeeding. However, further larger-scale studies need to be performed in order to clarify a yet uncertain matter.

Main Nutritional and Environmental Risk Factors in Children with Leukemia from a Public Hospital of the State of Guanajuato, Mexico

Introduction::

The prevalence of leukemia in children aged under 19 years continues to increase. Nutritional and environmental factors have been described as causes of their development, and maternal breastfeeding, birth weight, exposure to cow’s milk or to contaminants before 1 year of age, and smoking have been studied.

Objective::

To analyze the main nutritional and environmental risk factors in children with Acute Lymphoblastic Leukemia (ALL) in a public hospital in Guanajuato, Mexico.

Methods::

Analytical and cross-sectional study on 30 children under 18 years of age, with a confirmed diagnosis of ALL in a public hospital in Guanajuato, Mexico. With the signed informed consent of the children’s parents, a questionnaire was applied that collected and in which nutritional risk factors (weeks of gestation and birth weight, breastfeeding, exposure to cow’s milk) and environmental factors (smoking and exposure to arsenic) were evaluated. The frequencies and Odds Ratios (OR) of the main nutritional and environmental risk factors were obtained.

Results::

Mean age was 8 ± 4 years with 38 ± 1 weeks of gestation, with a birth weight of 3,200 g (range, 2,500-4,800 g). Fifty percent of the children consumed cow’s milk during their first year of life (40% before 6 months of age); 33.3% received maternal milk for ≤6 months and 63% of the parents had a positive smoking habit, with 66.6% of the participants living in cities with arsenic levels falling outside of the norm.

Conclusion::

The main nutritional and environmental risk factors found were early complementary feeding, cow’s milk prior to 1 year of age, a duration of breastfeeding of fewer than 6 months, birth weight of >3,500 g, a positive smoking habit in the children’s parents, as well as exposure to arsenic in drinking water. Identification of these risk factors could constitute an input for integrating novel prevention alternatives and the nutritional management of leukemia.

Infectious Agents in Bovine Red Meat and Milk and Their Potential Role in Cancer and Other Chronic Diseases

Red meat and dairy products have frequently been suggested to represent risk factors for certain cancers, chronic neurodegenerative diseases, and autoimmune and cardiovascular disorders. This review summarizes the evidence and investigates the possible involvement of infectious factors in these diseases. The isolation of small circular single-stranded DNA molecules from serum and dairy products of Eurasian Aurochs (Bos taurus)-derived cattle, obviously persisting as episomes in infected cells, provides the basis for further investigations. Gene expression of these agents in human cells has been demonstrated, and frequent infection of humans is implicated by the detection of antibodies in a high percentage of healthy individuals. Epidemiological observations suggest their relationship to the development multiple sclerosis, to heterophile antibodies, and to N-glycolylneuraminic acid (Neu5Gc) containing cell surface receptors.

Breastfeeding as a Protective Effect Against Childhood Leukemia and Lymphoma

BACKGROUND

Over the past several years, breastfeeding has been associated with many benefits as well as protective effects against many diseases. There is limited evidence for the relationship between breastfeeding and the incidence of leukemia.

OBJECTIVES

In this study, we evaluate the correlation of childhood leukemia and lymphoma with breastfeeding duration in children in southern Iran.

PATIENTS AND METHODS

Through this case control study, we compared 123 patients with leukemia and lymphoma to a control group of 137 healthy children. Statistical analysis was done using the Chi-square test and t-test as well as logistic regression methods. A P-value of less than 0.05 was considered significant.

RESULTS

Our findings showed that breastfeeding duration had no significant difference between cases and controls. However, the rural living percentage in patients with leukemia and lymphoma was higher than in the control group (39.8% versus 14.6% [P < 0.001 and OR = 3.87]) and parents' exposure to chemical materials during the war between Iran and Iraq was higher in sick patients (6.5% versus 0% [OR = 20.2%]).

CONCLUSIONS

The current study showed that breastfeeding duration has no protective effect against childhood leukemia and lymphoma. In addition, we suggest that some factors such as living in a rural area, smoking during pregnancy, parents' exposure to chemical materials and low socioeconomic status can increase the incidence rate of childhood leukemia and lymphoma.

Perceived Infant Feeding Preferences of Significant Family Members and Mothers' Intentions to Exclusively Breastfeed

BACKGROUND

Breastfeeding intention is a significant predictor of initiation and duration. The decision to breastfeed may be influenced by the opinions of family and friends.

OBJECTIVE

This study aimed to examine the relationship between maternal perception of the infant feeding preferences of the baby's father and the maternal grandmother and the woman's intention to breastfeed.

METHODS

This study analyzed data from the Infant Feeding Practices Survey II (2005-2007).

RESULTS

The sample included 4690 women, of whom approximately 82% were white, 67% were married, 68% were multiparous, and 66% had some college education or beyond. In adjusted analyses, the odds of intending to exclusively breastfeed in the first few weeks postpartum were higher among mothers who perceived that the baby's father or the maternal grandmother preferred exclusive breastfeeding (vs preferred other feeding) (fathers: odds ratio [OR] = 7.44; 95% confidence interval [CI], 6.20-8.92; maternal grandmothers: OR = 2.45; 95% CI, 2.01-2.99). Mothers in each of the racial/ethnic groups examined were more likely to intend to exclusively breastfeed in the first few weeks postpartum if they perceived that the expectant father preferred exclusive breastfeeding (vs preferred other feeding methods) (white: OR = 7.67; 95% CI, 6.25-9.41; black: OR = 11.76; 95% CI, 4.85-28.51; Hispanic: OR = 7.01; 95% CI, 3.44-14.28; other: OR = 7.51; 95% CI, 3.39-16.67).

CONCLUSION

These results suggest that significant family members should be counseled on the benefits of breastfeeding and the risks of formula feeding along with pregnant mothers.

Infection and childhood leukemia: review of evidence

OBJECTIVE

To analyze studies that evaluated the role of infections as well as indirect measures of exposure to infection in the risk of childhood leukemia, particularly acute lymphoblastic leukemia.

METHODS

A search in Medline, Lilacs, and SciELO scientific publication databases initially using the descriptors "childhood leukemia" and "infection" and later searching for the words "childhood leukemia" and "maternal infection or disease" or "breastfeeding" or "daycare attendance" or "vaccination" resulted in 62 publications that met the following inclusion criteria: subject aged ≤ 15 years; specific analysis of cases diagnosed with acute lymphoblastic leukemia or total leukemia; exposure assessment of mothers' or infants' to infections (or proxy of infection), and risk of leukemia.

RESULTS

Overall, 23 studies that assessed infections in children support the hypothesis that occurrence of infection during early childhood reduces the risk of leukemia, but there are disagreements within and between studies. The evaluation of exposure to infection by indirect measures showed evidence of reduced risk of leukemia associated mainly with daycare attendance. More than 50.0% of the 16 studies that assessed maternal exposure to infection observed increased risk of leukemia associated with episodes of influenza, pneumonia, chickenpox, herpes zoster, lower genital tract infection, skin disease, sexually transmitted diseases, Epstein-Barr virus, and Helicobacter pylori.

CONCLUSIONS

Although no specific infectious agent has been identified, scientific evidence suggests that exposure to infections has some effect on childhood leukemia etiology.

Maternal body mass index moderates the influence of smoking cessation on breast feeding

INTRODUCTION

Smoking cessation is associated with greater breast feeding in newly postpartum women, while being overweight or obese is associated with lower rates of breast feeding. The purpose of this study is to examine whether the increases in breast feeding associated with smoking cessation are moderated by maternal body mass index (BMI). To our knowledge, the interaction of maternal smoking status and overweight/obesity on breast feeding has not been previously reported.

METHODS

Participants (N = 370) were current or recent smokers at the start of prenatal care who participated in controlled trials on smoking cessation or relapse prevention during/after pregnancy. Study participants were followed from the start of prenatal care through 24 weeks postpartum. Smoking status was biochemically verified, and maternal reports of breast feeding were collected at 2-, 4-, 8-, 12-, and 24-week postpartum assessments.

RESULTS

Women who reported postpartum smoking abstinence or had a normal/underweight prepregnancy BMI (<25) were more likely to be breast feeding at the time that smoking status was ascertained (odds ratio [OR] = 3.02, confidence interval [CI] = 2.09-4.36, and OR = 2.07, CI = 1.37-3.12, respectively). However, smoking status and BMI interacted such that (a) normal/underweight women showed a stronger association between smoking abstinence and breast feeding (OR = 4.58, CI = 2.73-7.66) than overweight/obese women (OR = 1.89, CI = 1.11-3.23), and (b) abstainers showed an association between normal/underweight BMI and breast feeding (OR = 3.53, CI = 1.96-6.37), but smokers did not (OR = 1.46, CI = 0.88-2.44).

CONCLUSIONS

Overweight/obesity attenuates the positive relationship between smoking abstinence and greater breast feeding among newly postpartum women.

Care of the HIV-exposed child--to breast feed or not?

Breast milk is the best form of nutrition for infants. However, it places infants born to HIV infected women at risk of acquiring HIV infection. Total avoidance of breastfeeding is the only way of completely avoiding HIV transmission through breast milk. However, this strategy has not proved to be viable in resource constrained nations. A high infection related mortality and morbidity, and a high prevalence of malnutrition have been observed in HIV exposed infants on replacement feeding. Exclusive breastfeeding for the first six months followed by rapid weaning has also not proved to be a good strategy, with a surge in infection related morbidity and malnutrition reported after weaning. Current evidence indicates that continued use of ARV prophylaxis to mother/infant starting during pregnancy and continued to cover the entire duration of breastfeeding offers the infant best chance of HIV free survival, combining the benefits of breast milk with safety induced by ARV prophylaxis.

Current research continues to support breastfeeding benefits

Lamaze International and Lamaze Certified Childbirth Educators are strong supporters of breastfeeding. This paper reviews eight recent studies that are related to breastfeeding and useful to clinicians and educators.

Evolutionary perspectives on mother-infant sleep proximity and breastfeeding in a laboratory setting

Human maternal and infant biology likely coevolved in a context of close physical contact and some approximation of frequent, "infant-initiated" breastfeeding. Still, mothers and infants commonly sleep apart from one another in many western societies, indicating a possible "mismatch" between cultural norms and infant biology. Here we present data from a 3-night laboratory-based study that examines differences in mother-infant sleep physiology and behavior when mothers and infants sleep together on the same surface (bedsharing) and apart in separate rooms (solitary). We analyze breastfeeding frequency and interval data from the first laboratory night (FN) for 52 complementary breastfeeding mothers and infants (26 total mother-infant pairs), of which 12 pairs were routine bedsharers (RB) and 14 were routine solitary sleepers (RS). RB infants were 12.0 ± 2.7 (SD) weeks old; RS infants were 13.0 ± 2.4 weeks old. On the FN, RB mother-infant pairs (while bedsharing) engaged in a greater number of feeds per night compared to RS (while sleeping alone) (P < 0.001). RB also showed lower intervals (min) between feeds relative to RS (P < 0.05). When we evaluated data from all three laboratory nights (n = 36), post hoc, RB breastfed significantly more often (P < 0.01) and showed a trend towards lower intervals between feeds (P < 0.10). Given the widely known risks associated with little or no breastfeeding, the demonstrated mutually regulatory relationship between bedsharing and breastfeeding should be considered in future studies evaluating determinants of breastfeeding outcomes.

Protective effects of breastfeeding for mothers surviving childhood cancer

INTRODUCTION

Female childhood cancer survivors experience adverse health events secondary to cancer treatment. In healthy women, breastfeeding provides protection against many of these complications. Breastfeeding may be beneficial for mothers surviving childhood cancer by decreasing risks of, or ameliorating adverse late effects. Healthcare providers and survivors should be aware that successful lactation may be affected by previous cancer treatment.

METHODS

The literature addressing lactation outcomes in cancer patients is reviewed, and processes that may disrupt breastfeeding are discussed. A summary of common late effects experienced by women is provided, and arguments are made for the potential amelioration of these complications by breastfeeding.

RESULTS

Findings demonstrate that breastfeeding is beneficial for healthy mothers in regard to specific health conditions. There are limited data addressing breastfeeding outcomes among cancer survivors. Preliminary findings suggest that lactation is adversely affected among mothers treated for childhood cancer.

CONCLUSIONS

Fundamental research is needed to determine rates of breastfeeding in childhood cancer survivors, identify specific cancer therapies and their effects on lactation, examine the efficacy of breastfeeding in risk reduction and/or amelioration of late effects, and develop interventions to increase breastfeeding among survivors of childhood cancer.

IMPLICATIONS FOR CANCER SURVIVORS

As female childhood cancer survivors transition into adult medical care, it is important each patient be aware of her past medical history and the impact of treatment on her ability to successfully lactate. If lactation is possible, these women can choose to breastfeed their children, thereby engaging in a health behavior that may help protect them against many late effects of cancer treatment.

Health professional knowledge of breastfeeding: are the health risks of infant formula feeding accurately conveyed by the titles and abstracts of journal articles?

Effective promotion of breastfeeding is constrained if health professionals' knowledge on its importance is deficient. This study asks whether formula feeding is named as the risk factor in published research or whether it is considered the unspoken norm. A systematic analysis is conducted of the information content of titles and abstracts of 78 studies that report poorer health among formula-fed infants. This shows a surprising silence in the studies examined; formula is rarely named in publication titles or abstracts as an exposure increasing health risk. In 30% of cases, titles imply misleadingly that breastfeeding raises health risk. Only 11% of abstracts identify formula feeding as a health risk exposure. Initiatives to increase breastfeeding have described the importance of accurate language and well-informed health professional support. If widespread, this skew in communication of research findings may reduce health professionals' knowledge and support for breastfeeding.

Environmental factors and childhood acute leukemias and lymphomas

This review considers recent studies regarding the role of environmental factors in the etiology of childhood leukemia and lymphoma. Potential environmental risk factors identified for childhood leukemia include exposure to magnetic fields of more than 0.4 micro Tessla, exposure to pesticides, solvents, benzene and other hydrocarbons, maternal alcohol consumption (but only for certain genotypes), contaminated drinking water, infections, and high birth weight. The finding of space-time clustering and seasonal variation also supports a role for infections. There is little evidence linking childhood leukemia with lifetime exposure to ionizing radiation although fetal exposures to X-rays are associated with increased risk. Breast-feeding, consumption of fresh fruit and vegetables and having allergies all appear to be protective. Burkitt lymphoma (BL) is confined to areas of the world where malaria is endemic, with the additional involvement of the Epstein-Barr virus (EBV) as a co-factor. Environmental risk factors suggested for other types of non-Hodgkin lymphoma (NHL) include exposure to ionizing radiation (both lifetime and antenatal), pesticides, and, in utero exposure to cigarette smoke, benzene and nitrogen dioxide (via the mother). Hodgkin lymphoma (HL) is especially associated with higher levels of socioeconomic deprivation, but breast-feeding seems to confer lower risk. This is consistent with an infection or immune-response mediated etiology for HL.

Individual net-benefit maximization: a model for understanding breastfeeding cessation among low-income women

OBJECTIVES

We use economic theory of individual net benefit maximization to motivate a comprehensive look at 32 social, economic, and psychological disincentives that potentially influence breastfeeding cessation.

METHODS

The sample consists of 1,595 low-income families participating in the Healthy Steps for Young Children National Evaluation. Participants were recruited from 24 pediatric sites across the United States. Infants were enrolled at birth and followed through age 30-33 months. Survival analysis was used to assess the relation of social, economic and psychosocial factors with duration of breastfeeding.

RESULTS

Disincentives significantly associated with cessation in multivariate hazard analysis were: WIC participation at 2-4 months (HR = 1.50; 95% CI: 1.29, 1.74), mother's returning to work for 20-40 h per week (HR = 1.47; 95% CI: 1.26, 1.71), mother's not attending a postpartum doctor's visit (HR = 1.39; 95% CI: 1.18, 1.63), father's not being in the home (HR = 1.38; 95% CI: 1.21, 1.57), a smoker in the household (HR = 1.34; 95% CI: 1.17, 1.52), no receipt of breastfeeding instruction at the pediatric office (HR = 1.20; 95% CI:1.06, 1.37), the doctor's not encouraging breastfeeding (HR = 1.19; 95% CI: 1.01, 1.39) and the mother experiencing depressive symptoms (HR = 1.16; 95% CI: 1.02, 1.33).

CONCLUSIONS

The decision to stop breastfeeding is often complex. Research on breastfeeding cessation has been limited with regard to the social and economic issues that may influence the behavior of low-income women. The results support the need to develop interventions and policies to minimize disincentives associated with breastfeeding cessation.

Host, family and community proxies for infections potentially associated with leukaemia

Three hypotheses have proposed the involvement of infections in the aetiology of childhood leukaemia, suggesting either a specific leukaemogenic infection or a series of common infections that lead to a dysregulation of the immune system. Much of the evidence for the link with infections has been based on epidemiological observations, often using proxy measures of infection. Proxy measures include population mixing, parental occupation, age distribution of incidence, spatial and space-time clustering of cases, birth order and day care during infancy. This paper discusses the proxies used and examines to what extent a commonly used proxy measure, birth order, is a fair representation of either specific infections or general infectious load. It is clear that although leukaemia, and other diseases, may be linked with infections, one needs to (1) measure specific and general infections with more accuracy and (2) understand how proxy measures relate to real infections in the population.

Full breastfeeding and paediatric cancer

AIM

It has been suggested that there is an inverse association between breastfeeding and the risk of childhood cancer. We investigated the association between full breastfeeding and paediatric cancer (PC) in a case control study in Spain.

METHODS

Maternal reports of full breastfeeding, collected through personal interviews using the Paediatric Environmental History, were compared among 187 children 6 months of age or older who had PC and 187 age-matched control siblings.

RESULTS

The mean duration of full breastfeeding for cases were 8.43 and 11.25 weeks for controls. Cases had been significantly more often bottle-fed than controls (odds ratio (OR) 1.8; 95% confidence interval (CI) 1.1-2.8). Cases were significantly less breastfed for at least 2 months (OR 0.5; 95% CI 0.3-0.8), for at least 4 months (OR 0.5; 95% CI 0.3-0.8), and for 24 weeks or more (OR 0.5; 95% CI 0.2-0.9).

CONCLUSIONS

Breastfeeding was inversely associated with PC, the protection increasing with the duration of full breastfeeding. Additional research on possible mechanisms of this association may be warranted. Meanwhile, breastfeeding should be encouraged among mothers.

Benefits and risks of breastfeeding

In the absence of significant, unpreventable risks, breastfeeding should be the norm for the nourishment of human infants and should, therefore, be encouraged for populations in all countries. Continued efforts of international and national agencies and healthcare professionals to aid and abet breastfeeding, reduce the risks that occur in some women during breastfeeding, provide the safest substitutes for human milk when that is necessary, and encourage further research into the posed questions should considerably improve the health of many children.

Breast-feeding and Wilms tumor: a report from the Children's Oncology Group

OBJECTIVE

Previous research has shown that breast-feeding offers many nutritional benefits to children including protection against infection and possibly a decreased risk of childhood cancer. We investigated the association between breast-feeding and Wilms tumor, a childhood kidney tumor.

METHODS

We used data from a large case-control study in the United States and Canada. Cases were children under age 16 years who were diagnosed with Wilms tumor from 1999 to 2002 and were participating in the National Wilms Tumor Study. Controls were identified by random-digit dialing and were age and region matched to cases. Mothers of 501 cases and 480 controls provided information on breast-feeding by telephone interviews.

RESULTS

Breast-feeding was associated with a reduced risk of Wilms tumor [adjusted odds ratio (OR) = 0.7; 95% confidence interval (CI) = 0.5-0.9]. Longer duration did not provide any additional reduction in risk. When stratified by maternal education, breast-feeding lowered risk among children whose mothers had less than a college education (OR = 0.6; 95% CI = 0.4-0.8) but not for mothers who had a college degree or more (OR = 1.1; 95% CI = 0.6-1.9).

CONCLUSIONS

The results of this study are suggestive of an association between breast-feeding and Wilms tumor, but further research is needed to confirm this relationship.

Breast-feeding duration and childhood acute leukemia and lymphomas in a sample of Turkish children

OBJECTIVES

Whether breast-feeding is associated with decreased incidence of the lymphoid malignancies in children is uncertain. We evaluated childhood acute leukemia and lymphoma in relation to duration of breast-feeding.

METHODS

We investigated this issue in a case-control study comprising 137 patients, aged 1 to 16 years, with acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), Hodgkin or non-Hodgkin lymphoma, in addition to 146 controls matched for age and sex.

RESULTS

The median duration of breast-feeding among patients was shorter than that of controls (10 vs 12 months). Patients with ALL and AML had shorter mean breast-feeding duration compared with healthy children (P = 0.001 and P < 0.001, respectively). The shortest mean breast-feeding duration was noted in the children with AML. Breast-feeding for a duration of 0 to 6 months, when compared with feeding of longer than 6 months, was associated with increased odds ratios (ORs) for ALL [OR = 2.44, 95% confidence interval (CI) = 1.17-5.10], AML (OR = 6.67, 95% CI = 1.32-33.69), Hodgkin lymphoma (OR = 3.33, 95% CI = 0.60-18.54), non-Hodgkin lymphoma (OR = 1.90, 95% CI = 0.68-5.34) and overall (OR = 2.54, 95% CI = 1.51-4.26).

CONCLUSIONS

Our findings suggest that breast-feeding of more than 6 months is protective against childhood lymphoid malignancies, especially for AML and ALL.

Incidence and Characteristics of Childhood Hodgkin’s Lymphoma in Greece: A Nationwide Study (Greece)

OBJECTIVES

To estimate the incidence and epidemiological profile of childhood (0-14 years) Hodgkin's lymphoma in Greece derived by the network of childhood Hematology-Oncology departments on the basis of all 95 newly diagnosed cases during a seven-year period.

METHODS

Seventy-one of these cases were individually age and gender matched to an equal number of controls.

RESULTS

The incidence of childhood Hodgkin Lymphoma reached a relatively high figure of 7.8 per million children-years, with an age distribution (2.2 for children 0-4; 6.3 for those 5-9 and 13.9 for those 10-14-years-old) and male to female ratio (1.7:1) similar to that reported from other cancer registries. Childhood Hodgkin's lymphoma was more common among children living in less crowded quarters (odds ratio (OR): 6.5 and 95% confidence intervals (95% CI): 1.4-30.7), among those who have changed residence 60 to 18 months before the onset of the index disease (OR: 4.4, and 95% CI = 1.4-14.0), among those whose families owned a cat (OR: 5.5, 95% CI = 1.2-25.6) but not among those whose families owned a dog and marginally more common, among those with a history of infectious mononucleosis (OR: 5.0, 95% CI = 0.6-42.8).

CONCLUSIONS

Our results point to infectious agent(s) as playing an etiological role but do not allow discrimination among the delayed establishment of the herd immunity hypothesis, the population mixing hypothesis or that invoking transmission of the agent(s) from the non-human reservoir.

Aetiology of childhood leukemia

Leukemia is the most common cancer to affect children, accounting for approximately a third of all childhood cancers. The major morphological subtypes of leukemia, acute lymphoblastic leukemia (ALL), and acute myeloblastic leukemia (AML), are characterized by chromosomal translocations involving over 200 genes including mixed lineage leukemia (MLL), TEL, and AML1. Chromosomal translocations involving the MLL gene at 11q23 are a common feature of infant acute leukemia, found in up to 80% of all cases, and there is strong evidence that rearrangements involving the MLL gene or the TEL-AML1 gene fusion can originate in utero. As with most other cancers, the mechanism by which leukemia arises is likely to involve gene-environment interactions. Accordingly, it is important to identify exposures that cause DNA damage and induce chromosome breaks which are inadequately repaired, ultimately leading to the initiation and disease progression. Exposures acting before birth and early in life has long been thought to be important determinants of leukemia, and the list of suspected chemical, physical, and biological agents continues to increase. Unfortunately, the evidence regarding the majority of suggested exposures is limited and often contradictory, and there are areas, which clearly warrant further investigation in order to further our understanding of the aetiology of childhood leukemia.

Review of case-control studies related to breastfeeding and reduced risk of childhood leukemia

OBJECTIVE

To conduct a systematic review to evaluate the evidence for the effect of breastfeeding on the risk of developing childhood leukemia.

REVIEW METHODS

We sought studies providing data regarding the association of breastfeeding and occurrence of childhood leukemia. Studies were identified by using Medline, HHS Blueprint for Action on Breastfeeding, US Department of Health and Human Services Office on Women's Health, Cochrane Database of Systematic Reviews, National Centre for Reviews and Dissemination, reference lists, and national experts. Methodologic quality was evaluated for each study by using criteria from the US Preventive Services Task Force and the National Health Service Centre for Reviews and Dissemination.

RESULTS

We reviewed 111 citations to identify 32 potentially eligible full-text articles. Of the 10 studies reviewed, only 4 were sufficient to provide at least fair-quality evidence regarding the association between maternal breastfeeding and childhood leukemia. Studies conflicted regarding the protective effect of breastfeeding on childhood leukemia. In the 2 largest and highest quality studies, breastfeeding was associated with a significant risk reduction in one study with longer breastfeeding duration, reflecting greater protection, and a nonsignificant but suggestive difference in the other. Taken together, half of the studies associated breastfeeding with a lower risk of acute lymphocytic leukemia.

CONCLUSIONS

There are few high-quality studies that examine the potential for a protective effect of breastfeeding for childhood leukemia. Furthermore, the few studies that exist disagree regarding the association. It is estimated that the United States spends 1.4 billion dollars annually on the treatment of childhood leukemia. Patients, clinicians, and policy makers do not have the data that they need to make decisions regarding this important potential preventive measure.

Breastfeeding patterns and risk of childhood acute lymphoblastic leukaemia

The risk of childhood acute lymphoblastic leukaemia (ALL) was investigated in relation to breastfeeding patterns in the Northern California Childhood Leukaemia Study. Data collected by self-administered and in-person questionnaires from biological mothers of leukaemia cases (age 0-14 years) in the period 1995-2002 were matched to birth certificate controls on date of birth, sex, Hispanic ethnic status, and maternal race. Ever compared to never breastfeeding was not associated with risk of ALL at ages 1-14 years (odds ratio=0.99; 95% CI=0.64-1.55) and ages 2-5 years (OR=1.49; 95% CI=0.83-2.65). Various measures of breastfeeding duration compared to absence of breastfeeding also had no significant effect on risk. Complimentary feeding characteristics such as type of milk/formula used and age started eating solid foods among breastfed children were not associated with ALL risk. This study provides no evidence that breastfeeding affects the occurrence of childhood ALL.

Breastfeeding and the use of human milk

Considerable advances have occurred in recent years in the scientific knowledge of the benefits of breastfeeding, the mechanisms underlying these benefits, and in the clinical management of breastfeeding. This policy statement on breastfeeding replaces the 1997 policy statement of the American Academy of Pediatrics and reflects this newer knowledge and the supporting publications. The benefits of breastfeeding for the infant, the mother, and the community are summarized, and recommendations to guide the pediatrician and other health care professionals in assisting mothers in the initiation and maintenance of breastfeeding for healthy term infants and high-risk infants are presented. The policy statement delineates various ways in which pediatricians can promote, protect, and support breastfeeding not only in their individual practices but also in the hospital, medical school, community, and nation.

Breast-feeding and childhood cancer: A systematic review with metaanalysis

It has been suggested that breast milk may play a role in the prevention of certain childhood cancers. We undertook a systematic review of published studies investigating the association between breast-feeding and childhood cancers using Medline (1966 to June 2004), supplemented with auto alerts and manual searches. Analyses are based on odds ratios for specific cancers among those ever breast-fed compared with those never breast-fed, pooled using random-effects models. Forty-nine publications were potentially relevant; of these, 26 provided odds ratio estimates for at least one childhood cancer outcome and were included in metaanalyses. Overall, 92% of the studies were case-control studies, 85% relied on long-term recall of feeding history, only 8% examined breast-feeding exclusivity and control response rates were under 80% in over half. Metaanalyses suggested lower risks associated with having been breast-fed of 9% (95% CI = 2-16%) for acute lymphoblastic leukemia, 24% (3-40%) for Hodgkin's disease and 41% (22-56%) for neuroblastoma, with little between-study heterogeneity. The estimates for Hodgkin's disease and neuroblastoma, however, were driven by single studies. There was little evidence that breast-feeding was associated with acute nonlymphoblastic leukemia, non-Hodgkin's lymphoma, central nervous system cancers, malignant germ cell tumors, juvenile bone tumors, or other solid cancers. In conclusion, ever having been breast-fed is inversely associated with acute lymphoblastic leukemia, Hodgkin's disease and neuroblastoma in childhood, but noncausal explanations are possible. Even if causal, the public health importance of these associations may be small. Our estimates suggest that increasing breast-feeding from 50% to 100% would prevent at most 5% of cases of childhood acute leukemia or lymphoma. (c) 2005 Wiley-Liss, Inc.

An infectious aetiology for childhood acute leukaemia: a review of the evidence

There are three current hypotheses concerning infectious mechanisms in the aetiology of childhood leukaemia: exposure in utero or around the time of birth, delayed exposure beyond the first year of life to common infections and unusual population mixing. No specific virus has been definitively linked with childhood leukaemia and there is no evidence to date of viral genomic inclusions within leukaemic cells. The case-control and cohort studies have revealed equivocal results. Maternal infection during pregnancy has been linked with increased risk whilst breast feeding and day care attendance in the first year of life appear to be protective. There is inconclusive evidence from studies on early childhood infectious exposures, vaccination and social mixing. Some supportive evidence for an infectious aetiology is provided by the findings of space-time clustering and seasonal variation. Spatial clustering suggests that higher incidence is confined to specific areas with increased levels of population mixing, particularly in previously isolated populations. Ecological studies have also shown excess incidence with higher population mixing. The marked childhood peak in resource-rich countries and an increased incidence of the childhood peak in acute lymphoblastic leukaemia (ALL) (occurring at ages 2-6 years predominantly with precursor B-cell ALL) is supportive of the concept that reduced early infection may play a role. Genetically determined individual response to infection may be critical in the proliferation of preleukaemic clones as evidenced by the human leucocyte antigen class II polymorphic variant association with precursor B-cell and T-cell ALL.

Breastfeeding and the risk of childhood leukemia: a meta-analysis

OBJECTIVE

The authors used a meta-analytic technique to (1) quantify the evidence of an association between duration of breastfeeding and risk of childhood acute lymphoblastic leukemia (ALL) or acute myeloblastic leukemia (AML), (2) assess the influence of socioeconomic status (SES) on any such associations, and (3) discuss the implications of these findings for the evaluation of whether breastfeeding reduces the risk of childhood leukemia.

METHODS

A fixed effects model was employed to systematically combine the results of 14 case-control studies addressing the effect of short-term (< or = 6 months) and long-term (>6 months) breastfeeding on the risk of childhood ALL and/or AML. Subgroup analyses of studies that did and did not adjust for SES were also performed.

RESULTS

A significant, negative association was observed between long-term breastfeeding and both ALL risk (odds ratio [OR]=0.76; 95% confidence interval [CI] 0.68, 0.84) and AML risk (OR=0.85; 95% CI 0.73, 0.98). Short-term breastfeeding was similarly protective for ALL and AML. Results for studies that adjusted and did not adjust for SES were not significantly different from the results for the 14 studies combined.

CONCLUSIONS

This meta-analysis showed that both short-term and long-term breastfeeding reduced the risk of childhood ALL and AML, suggesting that the protective effect of breastfeeding might not be limited to ALL as earlier hypothesized. Potential bias introduced by different participation rates for case and control samples that differed in SES can be minimized by implementing larger case-control studies with SES-matched, population-based controls.

Causes of childhood leukaemia and lymphoma

Childhood cancer is rare comprising less than 1% of all malignancies diagnosed each year in developed countries. Leukaemia is the commonest form of cancer in children accounting for around a third of all childhood cancer, with acute lymphoblastic leukaemia (ALL) being the most prevalent. Biologically specific subtypes of ALL and acute myeloblastic leukaemia (AML), the other major morphological type of childhood leukaemia, are characterised by chromosomal changes. Whilst over 200 genes have been associated with chromosomal translocations, to date, only MLL, TEL, and AML1 have been linked with childhood leukaemia. Interestingly, there is increasing evidence to support the theory that gene rearrangements such as these may originate in utero. As with many other human diseases, both genetic and environmental factors have been implicated in the aetiology of the disease. Although much has been documented with regard to diet, smoking, alcohol consumption and recreational and prescription drug use during pregnancy, there is no consistent evidence to support a link with any of these factors and childhood leukaemia. However, findings from studies investigating prenatal and early life exposures are often based on small numbers of cases as both the type of cancer and exposure are rare. Furthermore, accurate information relating to past exposures can be difficult to obtain and is often reliant on self-reporting. To further our understanding of the aetiology of childhood leukaemia and lymphoma, there are areas which clearly warrant investigation. These include collection of parental dietary folate data combined with genetic analysis of the folate related genes, in utero exposure to DNA topoisomerase II inhibitors, and the possible effects of assisted reproduction technology on disease susceptibility.

Human breast milk suppresses the transcriptional regulation of IL-1beta-induced NF-kappaB signaling in human intestinal cells

Neonatal necrotizing enterocolitis (NEC), which is a disease with a poor prognosis, is considered to be caused by the coincidence of intestinal ischemia-reperfusion injury and systemic inflammation due to the colonization of pathogenic bacteria. Interleukin (IL)-8, a proinflammatory cytokine, plays an important role in the pathophysiology of NEC. It was recently reported that IL-1beta activates the IL-8 gene by regulating the transcriptional nuclear factor kappaB (NF-kappaB) signaling pathways in intestinal cells. The protective role of maternal milk in NEC pathogenesis has been reported in both human and animal studies. In this study, we show that human breast milk dramatically suppressed the IL-1beta-induced activation of the IL-8 gene promoter by inhibiting the activation pathway of NF-kappaB. Moreover, we also show that human breast milk induced the production of IkappaBalpha. These results suggest that human breast milk could be protective and therapeutic in neonates with NEC by inhibiting the activation pathway of NF-kappaB.

Day care, childhood infections, and risk of neuroblastoma

Neuroblastoma is the most common cancer in infants worldwide, but little is known about its etiology. Infectious etiologies involving the immune system have been hypothesized for some childhood cancers, especially leukemia, but the role of infectious agents in neuroblastoma has not been fully investigated. The authors used data from a large case-control study conducted by the Children's Oncology Group in the United States and Canada in 1992-1994 to investigate whether there was any relation among day-care attendance, childhood infections, allergies, and neuroblastoma. They interviewed mothers of 538 case children and 504 age-matched control children by telephone about several factors, including pregnancy, medical history, lifestyle, and childhood medical conditions and exposures. The results suggested decreased risks associated with day-care attendance (odds ratio (OR) = 0.81, 95% confidence interval (CI): 0.56, 1.17), childhood infectious diseases (chickenpox, mumps, red measles, and German measles) (OR = 0.60, 95% CI: 0.39, 0.93), and allergies (OR = 0.68, 95% CI: 0.44, 1.07). The authors found reduced neuroblastoma risk associated with markers of potential childhood infections. This suggests a possible role of infectious agents in neuroblastoma etiology. Future epidemiologic studies should incorporate more direct data on infection.

Infectious diseases in the first year of life, perinatal characteristics and childhood acute leukaemia

The objective of the present study was to investigate the role of early common infections and perinatal characteristics in the aetiology of childhood common leukaemia. A case–control study was conducted from 1995 to 1998 in France, and included 473 incident cases of acute leukaemia (AL) (408 acute lymphoblastic leukaemia (ALL), 65 acute myeloid leukaemia (AML) age-, sex- and region-matched with 567 population-based controls. Data on the medical history of the child and his/her environment were collected using self-administered questionnaires. Analyses were conducted using nonconditional logistic regression. A slight negative association with early infections was observed (OR=0.8; 95% CI (0.6–1.0)). The association was stronger for early gastrointestinal infections. Early day-care was found to be associated with a decreased risk of AL (OR=0.6; 95% CI (0.4–0.8) and OR=0.8; 95% CI (0.5–1.2) for day-care starting before age 3 months and between 3 and 6 months, respectively). No association with breast-feeding was observed, irrespective of its duration. A birth order of 4 or more was associated with a significantly increased risk of AL (OR=2.0; 95% CI (1.1–3.7) with ALL). A history of asthma was associated with a decreased risk of ALL (OR 0.5; 95% CI (0.3–0.90). Although the results regarding birth order and breast-feeding do not fit with Greaves' hypothesis, the study supports the hypothesis that early common infections may play a protective role in the aetiology of childhood leukaemia, although this effect was not more marked for common ALL.

Low breastfeeding rates and public health in the United States

The medical community has orchestrated breastfeeding campaigns in response to low breastfeeding rates twice in US history. The first campaigns occurred in the early 20th century after reformers linked diarrhea, which caused the majority of infant deaths, to the use of cows' milk as an infant food. Today, given studies showing that numerous diseases and conditions can be prevented or limited in severity by prolonged breastfeeding, a practice shunned by most American mothers, the medical community is again inaugurating efforts to endorse breastfeeding as a preventive health measure. This article describes infant feeding practices and resulting public health campaigns in the early 20th and 21st centuries and finds lessons in the original campaigns for the promoters of breastfeeding today.

Day-care, early common infections and childhood acute leukaemia: a multicentre French case-control study

We conducted a case-control study to investigate the role of early infections in the aetiology of childhood acute leukaemias. The study included 280 incident cases (240 acute lymphoblastic leukaemia and 40 acute non-lymphoblastic leukaemia) and 288 hospital controls, frequency matched by age, gender, hospital, catchment area of the hospital and ethnic origin. Data were obtained from standardised face-to-face interviews of the mothers. The interviews included questions on early common infections, day-care attendance, breast-feeding, birth order and infantile diseases. Odds ratios were estimated using an unconditional regression model including the stratification variables, parental socio-economic status and perinatal characteristics. Birth order was not associated with childhood leukaemia (acute lymphoblastic or acute non-lymphoblastic). A statistically-significant inverse association was observed between childhood leukaemia and day-care attendance (odds ratio=0.6, 95% Confidence Interval=(0.4-1.0)), repeated early common infections (> or = 4 per year before age two, odds ratio=0.6 (0.4-1.0)), surgical procedures for ear-nose-throat infections before age two (odds ratio=0.5 (0.2-1.0)) and prolonged breast-feeding (> or = 6 months, odds ratio=0.5 (0.2-1.0)). In the multivariate model including day-care attendance, early common infections and breast-feeding, results concerning breast-feeding remained unchanged. A statistically significant interaction between day-care attendance and repeated early common infections was observed. When the interaction was taken into account, the simple effects of day-care and early common infections disappeared (odds ratio=1.1 (0.5-2.3) and odds ratio=0.8 (0.5-1.3), respectively) while the joint effect of day-care attendance and early common infections was negatively associated with childhood leukaemia (odds ratio=0.3 (0.1-0.8)). All the above associations were observed both for acute lymphoblastic leukaemia and acute non-lymphoblastic leukaemia. Our results support Greaves' hypothesis, even though they are not specific of common leukaemia.

Breastfeeding

A large and growing body of scientific evidence suggests that breastfeeding provides immediate and long-lasting health advantages for the mother and her infant. In the United States, breastfeeding rates currently are the highest recorded in 30 years, although premature weaning owing to the largely avoidable problems of breast pain and concern about adequate milk supply is still common. The advantages of breastfeeding will be more widely appreciated when all health care professionals acquire competence in evidence-based lactation management strategies. These strategies include helping women to position and attach their newborns correctly, encouraging frequent and effective feedings at the breast from birth onward, teaching new parents the signs of adequate milk intake, and providing the resources for promoting breastfeeding without the competition of commercial product promotion.

Breastfeeding and childhood cancer

The relationship between childhood cancer and having been breastfed in infancy was investigated in the UK Childhood Cancer Study (UKCCS), a national, population-based case-control study. Analyses included 3500 children with cancer (cases) of whom 1637 were diagnosed with leukaemia, 114 with Hodgkin's disease, 228 with non-Hodgkin's lymphoma and 1521 with other cancer and 6964 controls. 62% cases and 64% controls were reported to have ever been breastfed. There was weak evidence, of borderline statistical significance, that having been breastfed was associated with a small reduction in the odds ratios for leukaemia (odds ratio = 0.89, 95% Cl 0.80-1.00, P = 0.06), and for all cancers combined (odds ratio = 0.92, 95% Cl 0.84-1.00, P = 0.05). Combining data from the UKCCS with results from other published studies showed a small reduction in the odds ratios for leukaemia, Hodgkin's disease, non-haematological cancers, and all childhood cancers combined, associated with ever having been breastfed. It is unclear whether the apparent small reduction in the odds ratio for these various types of childhood cancer is a generalized effect of breastfeeding or whether it reflects some systematic bias in the majority of studies that have investigated the question.