e22011 Background: The incidence of childhood cancers increased by 1 % per year over the last three decades. Life style changes and increased variety of environmental exposures are accused of this trend. One of these environmental factors is cigarette smoking and parental smoking is the main source of tobacco smoke exposure of children. There are strong reasons for considering parental smoking behaviour as a risk factor for childhood cancers. Many tobacco related compounds are detected in fetal tissues, breast milk and tissues of children of smoking parents. However, it is hard to make causal relationship between parental smoking and childhood cancers. One of the reasons is the difficulty to detect tobacco smoke exposure. Questionnaires, commonly used method to detect tobacco smoke exposure, are prone to biases. Cotinine is the main metabolite of nicotine which is the abundant organic compound in tobacco and a good biomarker to detect tobacco smoke exposure. Methods: 104 newly diagnosed, 0-18 years aged pediatric cancer patients from two pediatric oncology centers ( Ankara University Children’s Hospital and Ankara City Hospital) and 99 healthy children aged 0-18 applied to the Ankara University Children’s Hospital participated our study. Parental smoking behaviours (preconceptional, during pregnancy and current smoking) and environmental tobacco smoke exposures (ETS) of children were compared between two groups. ETS exposures of cancer patients and healthy children were evaluated by hair cotinine ELISA analysis and questionnaire. For hair cotinine analysis, 30 mg of hair samples were taken from occipital part of scalp by a stainless scissors. Samples were processed according to manufacturer's instructions. Parents of two groups were surveyed about their smoking behaviours and ETS exposures of their children. Results: We found no differences between two groups by means of maternal preconceptional smoking, smoking during pregnancy and current smoking behaviours. Paternal preconceptional smoking and smoking during pregnancy rates were significantly low in cancer patients (p < 0,05) according to questionnaire. Environmental tobacco smoke exposures were found statistically low in cancer patients according to questionnaire (p < 0,05). However, quantitative exposure assessment by hair cotinine analysis revealed that cancer patients are exposed to tobacco smoke more than healthy children (p < 0,001). Conclusions: Our findings support that smoking could be a risk factor for childhood cancers. This study also revealed that questionnaires could cause biases. We thought, social desirability bias of father of cancer patients could be a reason of their low smoking rates according to questionnaire. We suggest that cotinine analysis along with validated questionnaires can be used to prevent biases in studies of tobacco smoke in the etiology of childhood cancers.
Parental smoking during pregnancy, early growth, and risk of obesity in preschool children: the Generation R Study