Infection and childhood leukemia: review of evidence

Abstract

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

A systematic review and meta-analysis of the association between childhood infections and the risk of childhood acute lymphoblastic leukaemia

“…As in previous reviews, there continues to be substantial heterogeneity among the studies; however, our review focuses on specific objectives and highlights the recent developments of the field (McNally and Eden, 2004; Buffler et al , 2005; Greaves, 2006; Ma et al , 2009; Maia Rda and Wunsch Filho, 2013). There are several limitations of this study.…”

“…Other methods for measuring infections such as using administrative data overcome these limitations, but may lack information on important confounders. Other than narrative summaries (McNally and Eden, 2004; Buffler et al , 2005; Ma et al , 2009; Maia Rda and Wunsch Filho, 2013), no study has attempted to synthesise and quantitatively pool studies examining the relationship using a history of infections, or tried to explain the differences between the studies. The aim of this systematic review and meta-analysis was to assess the relationship between childhood infections, and the development childhood ALL by summarising the findings for an overall measure of infections, the frequency, severity, timing of infections, and examining specific infectious agents and syndromes.…”

Developmental Tuning of Epigenetic Clock

“…The overhygienization is becoming increasingly widespread in modern world, and it is believed to cause increased antibiotic resistance and permanently increasing number of persons with weakened immunity in developed societies ( Bloomfield et al, 2016 ). Although lack of microbial exposure may not be the only causal factor, the assumptions of this hypothesis have been repeatedly confirmed through both observational and experimental studies ( Maia Rda and Wünsch Filho, 2013 ). Under-using of immune system early in life can likely cause not only atopic conditions, but also autoimmune states ( Kramer et al, 2013 ).…”

Livestock and poultry density and childhood cancer incidence in nine states in the USA

“…Exposure to animals in early childhood has been associated with decreased development of allergies (Campo et al 2006; Ownby et al 2002) and allergies have been inversely associated with leukemia risk in children and adults (Linabery et al 2010; Nanni et al 1996; Schuz et al 2003; t Mannetje et al 2012). Additionally, maternal infections during pregnancy or early life infections in children have been positively associated with childhood leukemia in some studies (Maia Rda and Wunsch Filho 2013). Studies have shown that infection with viruses found in animals, such as avian sarcoma virus (Copeland et al 1975), oncornaviruses, papovaviruses, and adenoviruses (Swenberg 1977) can lead to the development of brain tumors in animals.…”