title: Epidemiology of breast cancer.
abstract: Breast cancer is the commonest cause of cancer death in women worldwide. Rates vary about five-fold around the world, but they are increasing in regions that until recently had low rates of the disease. Many of the established risk factors are linked to oestrogens. Risk is increased by early menarche, late menopause, and obesity in postmenopausal women, and prospective studies have shown that high concentrations of endogenous oestradiol are associated with an increase in risk. Childbearing reduces risk, with greater protection for early first birth and a larger number of births; breastfeeding probably has a protective effect. Both oral contraceptives and hormonal therapy for menopause cause a small increase in breast-cancer risk, which appears to diminish once use stops. Alcohol increases risk, whereas physical activity is probably protective. Mutations in certain genes greatly increase breast-cancer risk, but these account for a minority of cases.
authors.affiliation: Imperial Cancer Research Fund Cancer Epidemiology Unit, University of Oxford, UK. key@icrf.icnet.uk
authors.forename: T J
authors.initials: TJ
authors.lastname: Key
authors.forename: P K
authors.initials: PK
authors.lastname: Verkasalo
authors.forename: E
authors.initials: E
authors.lastname: Banks
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000628:therapy; D003276:Contraceptives, Oral / Q000009:adverse effects; D004032:Diet; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D012307:Risk Factors
chemical_list: D003276:Contraceptives, Oral