ABSTRACT

Epidemiology • Breast cancer is the leading cause of death among women. • The lifetime risk is approximately 10%. • The average incidence is 65 per 100 000 individuals per year.

Aetiology • Risk factors include:

- early menarche (the relative risk is 1.5) - late menopause (early menopause is protective) - obesity after the menopause (pre-menopausal obesity is

protective) - nulliparity (increases risk by 30%) - late pregnancy (e.g. after the age of 35 years) - benign breast disease, especially atypical epithelial hyper­

plasia - oral contraceptives - hormone replacement therapy (seems to increase the risk by

35% after use for 5 years) - family history of breast cancer. The risk is particularly high

in the first-degree relatives of patients with early onset of breast cancer (age < 45 years) and/or bilateral breast cancer

- alcohol consumption is associated with increased risk - ionising radiation. The risk increases with radiation dose.