Exposição pré-natal ao tabagismo e tumores cerebrais na infância: uma revisão sistemática.

Abstract

Childhood brain tumors are the leading cause of cancer death in children and, in addition to some genetic syndromes and ionizing radiation, their etiology is largely unknown. Parental smoking, which is relatively frequent, could play a role in tumorigenesis of cancer of the central nervous system and requires further exploration. OBJECTIVE: To observe whether there is an association between prenatal exposure to parental smoking and the occurrence of brain tumors in childhood. METHODS: Systematic review with data from cohort and case-control studies on prenatal exposure to smoking and brain tumors in childhood using the descriptors: "tumores cerebrais", "gravidez", "tabagismo" and their correspondents in English, in the Virtual Databases: LILACS, MEDLINE, PubMed and Scielo in the Portuguese, English and Spanish languages. RESULTS: There were no or weak association between childhood brain tumors and maternal smoking, being seen greater influence only in children less than 24 months and between 5 and 9 years of age. Astrocytomas and the male sex were the most involved after stratification. Another more significant association was observed among children with brain tumors whose parents smoked within one year before birth and during gestation, regardless of the number of cigarettes smoked per day. This relationship was even greater when analyzed in age groups of children younger than 4 years. Again, astrocytoma was the most strongly associated histologic type. Already the consumption of more than 15 cigarettes a day implied in the increased risk for ependymomas and embryonic tumors. CONCLUSION: There was a greater risk of developing childhood brain tumors through paternal smoking, to the detriment of the maternal, which may point to the possibility of paternal smoking act not only in the exposure of the fetus to passive smoking but also as inducer of epigenetic changes in human sperm.