title: A case-control study of body mass index and breast cancer risk in white and African-American women.
abstract: OBJECTIVE
  Large body size has been associated with decreased risk of breast cancer in premenopausal women but with increased risk in postmenopausal women. Limited information is available about African-American women and differences by estrogen and progesterone receptor status.
  
  
  METHODS
  We analyzed data from the Women's Contraceptive and Reproductive Experiences Study among 3,997 white and African-American breast cancer case patients diagnosed in 1994 to 1998 and 4,041 control participants ages 35 to 64 years. We calculated multivariate odds ratios (OR) as measures of relative risk of breast cancer associated with self-reported body mass index (BMI) at age 18 and 5 years before diagnosis (recent BMI).
  
  
  RESULTS
  Risk tended to decrease with increasing BMI at age 18 years in all women [OR(BMI > or = 25 kg/m(2) versus < 20 kg/m(2)) = 0.76; 95% confidence interval (CI), 0.63-0.90; P(trend) = 0.005] and with recent BMI in premenopausal women (OR(BMI > or = 35 kg/m(2) versus < 25 kg/m(2)) = 0.81; 95% CI, 0.61-1.06; P(trend) = 0.05), unmodified by race. Among postmenopausal white but not African-American women, there was an inverse relation between recent BMI and risk. High recent BMI was associated with increased risk of estrogen receptor- and progesterone receptor-positive tumors among postmenopausal African-American women (OR(BMI > or = 35 kg/m(2) versus < 25 kg/m(2)) = 1.83; 95% CI, 1.08-3.09; P(trend) = 0.03).
  
  
  CONCLUSIONS
  Among women at age 35 to 64 years, BMI at age 18 years is inversely associated with risk of breast cancer, but association with recent BMI varies by menopause status, race, and hormone receptor status.
  
  
  CONCLUSIONS
  Our findings indicate that studies of BMI and breast cancer should consider breast cancer subtypes.
authors.affiliation: Institute of Basic Medical Sciences, Department of Nutrition, University of Oslo, Oslo, Norway. p.m.berstad@medisin.uio.no
authors.forename: Paula
authors.initials: P
authors.lastname: Berstad
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Coates
authors.forename: Leslie
authors.initials: L
authors.lastname: Bernstein
authors.forename: Suzanne G
authors.initials: SG
authors.lastname: Folger
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: Malone
authors.forename: Polly A
authors.initials: PA
authors.lastname: Marchbanks
authors.forename: Linda K
authors.initials: LK
authors.lastname: Weiss
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Liff
authors.forename: Jill A
authors.initials: JA
authors.lastname: McDonald
authors.forename: Brian L
authors.initials: BL
authors.lastname: Strom
authors.forename: Michael S
authors.initials: MS
authors.lastname: Simon
authors.forename: Dennis
authors.initials: D
authors.lastname: Deapen
authors.forename: Michael F
authors.initials: MF
authors.lastname: Press
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Burkman
authors.forename: Robert
authors.initials: R
authors.lastname: Spirtas
authors.forename: Giske
authors.initials: G
authors.lastname: Ursin
mesh_terms: D000328:Adult; D001741:Black or African American; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000208:ethnology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D017697:Premenopause; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D044465:White People