[Epidemiology of cancer of the breast]

Breast cancer is a major public health problem. In 1980, breast cancer represented 18% of all cancers in women throughout the world. The worldwide incidence of breast cancer is increasing by 1.5% per annum and is influenced by geographical factors and by age. In France, this disease represents 19% of cancer deaths in women and is the commonest cause of cancer death in women. Several risk factors have been suspected, but many points remain obscure. The age of the menarche, the age of menopause, parity and the age of the first pregnancy influence the incidence of breast cancer. The use of oral contraceptives and hormone replacement therapy for menopause do not appear to affect the development of malignant breast disease, except, perhaps, in certain subgroups of patients, but this remains to be confirmed. The risk is increased by a fatty diet and by excessive alcohol consumption. It is now generally accepted that a family history of breast cancer is associated with an increased risk. In the future, a more precise understanding of genetic anomalies related to cancer will allow early diagnosis, particularly of familial forms. Many unresolved aspects of the risk factors of breast cancer could be elucidated by cohort studies.