Effects of lifestyle on the onset of puberty as determinant for breast cancer.

Breast cancer is more than ever the leading cause of death in women. In this article, we investigate the influence of lifestyle factors, and in particular nutrition (i.e. soft drinks), on physical development, puberty, breast growth and menarche to understand the potential impact of these environmental and lifestyle factors on the induction of breast cancer susceptibility. A questionnaire was obtained from 1146 girls of 10 schools in Belgian Limburg, attending the second year of secondary school. Their mean age was about 13 years. The analyses of the data were performed with 'survival analysis', in particular with the 'Cox regression' model for menarche. This project was conducted in the school year of 1999-2000. In the univariate and multivariate analysis investigating the most important variables of the period from birth to the age of menarche, there was clear evidence that lifestyle factors, including nutrition, have an effect on breast development and menarche. The following variables were significantly related to breast development and menarche: body mass index, drinking high-carbohydrate drinks, i.e. soft drinks, height of the father and the mother, weight of the mother at the start of pregnancy, history of mononucleosis, origin and education of the parents and physical activity. Lifestyle factors, including nutrition (i.e. soft drinks), affect the age at puberty and menarche. The same factors are known to be related to breast cancer risk. Better control of these variables during puberty might reduce breast cancer risk later in life.