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.
DESCRIPTORS:Children. Leukemia, etiology. Causality. Infection. Review. Leukemia makes up about one third of all malignancies in the 0-14 year old age group. The most common subtype, acute lymphoblastic leukemia (ALL), represents about 80.0% of these cases. 57 The incidence rate of ALL was estimated as 35.2 per million children aged under 15 in Brazil, and children under five are the most affected.
60Potential risk factors for childhood leukemia (CL) are conflicting. Exposure to ionizing radiation, commonly accepted as a cause of leukemia, does not explain all cases of leukemia in children.5 The etiology of CL has a multifactorial character. Leukemic cells that carry genetic alterations arise mainly before birth. Translocation between chromosomes 12 and 21 causes fusion of the TEL and AML1 gene; producing aberrant proteins that inhibit gene activity and change the capacity for self-renewal and differentiation of hematopoietic stem cells; this change represents the most common structural genetic abnormality in children with leukemia.45,74 About 1.0% of healthy newborns have this translocation and one RESUMO OBJETIVO: Analisar estudos que avaliaram o papel de infecções e de medidas indiretas de exposição às infecções no risco de leucemia infantil, principalmente da leucemia linfocítica aguda.
MÉTODOS:A busca nas bases de dados Medline, Lilacs e SciELO utilizando-se inicialmente os de...