title: Risk factors for breast cancer in elderly women.
abstract: As the population ages, an increasing fraction of women diagnosed with breast cancer will be elderly. Heterogeneity of breast cancer risk factors between pre- and postmenopausal women is recognized, but few studies have examined elderly women specifically. The authors describe the age-specific influence of risk factors for postmenopausal breast cancer, with emphasis on women aged 75 or more years. Among 36,658 members of the Iowa Women's Health Study (1986-2001), a population-based cohort study, 428 incident breast cancers were diagnosed in women aged 55-64 years, 1,297 in women aged 65-74 years, and 561 in women aged 75-84 years. Women with a body mass index (weight (kg)/height (m)(2)) in the highest versus the lowest quartile were at increased risk of breast cancer at age 75 or more years (adjusted hazard ratio = 1.44, 95% confidence interval (CI): 1.12, 1.84). Family history of breast cancer (hazard ratio = 1.54, 95% CI: 1.24, 1.93 for a first-degree family history vs. none) and an older age at menopause (p(trend) = 0.07) conferred increased risk for women aged 75 or more years, and a high number of livebirths was protective (hazard ratio = 0.67, 95% CI: 0.51, 0.88 for five or more births compared with one or two). Obesity, a modifiable risk factor, remained positively associated with breast cancer for all age groups of postmenopausal women.
authors.affiliation: University of Minnesota, Minneapolis, MN, USA. Carol.Sweeney@hrc.utah.edu
authors.forename: Carol
authors.initials: C
authors.lastname: Sweeney
authors.forename: Cindy K
authors.initials: CK
authors.lastname: Blair
authors.forename: Kristin E
authors.initials: KE
authors.lastname: Anderson
authors.forename: DeAnn
authors.initials: D
authors.lastname: Lazovich
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Folsom
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D015994:Incidence; D007484:Iowa / Q000453:epidemiology; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D016017:Odds Ratio; D010298:Parity; D010375:Pedigree; D011159:Population Surveillance; D017698:Postmenopause; D016016:Proportional Hazards Models; D011960:Receptors, Estrogen / Q000032:analysis; D017584:Reproductive History; D018570:Risk Assessment; D012307:Risk Factors; D018426:SEER Program; D011795:Surveys and Questionnaires
chemical_list: D011960:Receptors, Estrogen