[Epidemiology of breast cancer]

Breast cancer is the predominant cancer among women in France, accounting for about 32% of all new cases. Increasing incidence rates are reported by the regional registries, while the national mortality rates seem to reach a plateau particularly in the women under 65 years old. During the last 20 years the survival of patients with positive nodes has been increased. Nulliparity and increasing age at first birth are well established risk factors as well as age at menarche and age at menopause (OR approximately equal to 2). The role of other risk factors such as hormone replacement therapy, oral contraception, lactation remain controversial (OR approximately equal to 1-1.5). Total calories consumption, obesity after menopause, and alcohol are possible risk factors (OR approximately equal to 2-3). Previous irradiation of thorax, proliferative benign mastopathy are increasing the risk of breast cancer (OR approximately equal to 3-5). Consumption of fruits and vegetables, as well as physical exercise could decrease the risk (OR approximately equal to 0.6). There is a strong heredity component for about 10-15% of the cases. Approximately in half of these cases a mutated gene (Brca1, Brca2 ...) have been identified.