Epidemiology of breast cancer: the Nordic contribution.

In the Nordic countries, breast cancer, is the most common malignant disease among women and the incidence has been increasing steadily for the past 30 years. The age-specific incidence curve of female breast cancer suggests that the menopause has a protective effect. Nordic studies have provided evidence of an increased breast cancer risk in women of low parity, those who have their first child late, and those who have used oral contraceptives and hormone replacement therapy for a long time.