title: Oral contraceptives and breast cancer.
abstract: The incidence of breast cancer among users and non-users of oral contraceptives (OCs) was determined at Group Health Cooperative of Puget Sound, Seattle, Washington, a health care organization which maintains computer files of diagnoses and outpatient drug use. In women 45 years of age or younger, the incidence was nearly identical in users and non-users. In premenopausal women over 45 years of age, there was a positive association between current OC use and breast cancer, the risk ratio estimates and 90% confidence intervals being 4.0 (1.8-9.0) in women 46-50 years of age and 15.5 (5.2-46) in women 51-55 years of age.
mesh_terms: D000328:Adult; D000367:Age Factors; D001943:Breast Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D003276:Contraceptives, Oral / Q000009:adverse effects*; D004967:Estrogens / Q000009:adverse effects; D005260:Female; D006801:Humans; D008593:Menopause; D008875:Middle Aged; D012306:Risk; D014861:Washington
chemical_list: D003276:Contraceptives, Oral; D004967:Estrogens