RESUMO
AIM: Although tobacco smoke is an established risk factor for adult cancer, studies of the association between parental smoking and childhood cancer have produced inconsistent results. To investigate the transgenerational relationship between pre-natal and post-natal tobacco smoke exposure from the grandmother's pregnancies until after the post-natal period and childhood cancer. METHODS: Exposure to tobacco smoke was recorded for three generations. Data were collected through personal interviews using the paediatric environmental history, and were compared among 128 children with cancer and 128 matched controls. The contingency tables and a logistic multivariable regression model were used to control for possible confounding factors. RESULTS: Smoke exposure during oogenesis (maternal grandmother smokers)--odds ratio (OR) 2.2 (95% confidence interval (CI) 1.1-4.9)--and during the mother' pregnancies--OR 1.8 (95% CI 1.1-3.3)--were significantly associated with an increased risk of childhood cancer. CONCLUSIONS: Tobacco smoke exposure during the grandmother's and mother's pregnancies increase the risk of cancer in the descendants. The results suggest that the biological plausibility of the association between parental smoking and paediatric cancer can be explained by the large latency period of paediatric carcinogenesis.