[Epidemiology of breast cancer]

Important facts and hypotheses of descriptive and analytic epidemiology of breast cancer are presented and discussed in connection with results of studies carried out by the authors. Leading position and further increase in breast cancer incidence in many countries are the most important point of descriptive epidemiology. In the GDR breast cancer incidence amounts to 60 per 100,000 per year. On the other hand, there are large differences in the incidence between populations, which support hypotheses about the life style, especially of diet, as a risk factor for breast cancer. The most important groups of risk factors which have been investigated are menstrual and reproductive factors, genetics, hormonal status, diet, benign breast disease, radiation and oral contraceptives. Early age at menarche and late age at menopause, nulliparity and late age at first birth, breast cancer in first-degree relatives, benign breast disease and radiation increase breast cancer risk. The results of case-control studies concerning diet are not yet convincing. A number of studies shows no overall increase of breast cancer risk. Finally, possibilities of breast cancer control are discussed.