title: Weight change and risk of postmenopausal breast cancer (United States).
abstract: OBJECTIVE
  Although many studies have shown that higher weight increases the risk of postmenopausal breast cancer, some aspects of this association are unclear. In order to examine the risk associated with different patterns of weight change, we analyzed data from a large case-control study of postmenopausal breast cancer.
  
  
  METHODS
  Participants included women aged 50 79 years (n = 5031) who are newly diagnosed with invasive breast cancer in Massachusetts, New Hampshire, and Wisconsin. Similarly-aged population controls (n = 5255) were selected at random from driver's license files and Medicare beneficiary lists. Height, weight, and information on other breast cancer risk factors were ascertained by structured telephone interviews from 1992 to 1995, and logistic regression was used to estimate multivariable-adjusted odds ratios (OR) and 95% confidence intervals (CI).
  
  
  RESULTS
  Women in the top quintile groups for height at age 20, recent weight, and recent body mass index had significantly increased risks of breast cancer. Among women who reached their highest adult weight at younger ages (<45 years), increasing weight loss since that age was associated with a reduced risk of postmenopausal breast cancer (OR 0.90, CI 0.84 0.98, per 5 kg). However, weight loss among women whose highest weight occurred after age 45 was not associated with risk (OR 1.00, CI 0.95 1.05, per 5 kg). Weight gain since the lowest adult weight increased risk by 8% for each 5 kg of gain (OR 1.08, CI 1.06-1. 11). Temporary weight cycling (weight loss followed by weight gain) was not associated with increased risk.
  
  
  CONCLUSIONS
  Weight gain clearly increased risk of postmenopausal breast cancer. These data lend further support to efforts aimed at helping women avoid weight gain as they age.
authors.affiliation: University of Wisconsin Comprehensive Cancer Center, Madison, USA.
authors.forename: A
authors.initials: A
authors.lastname: Trentham-Dietz
authors.forename: P A
authors.initials: PA
authors.lastname: Newcomb
authors.forename: K M
authors.initials: KM
authors.lastname: Egan
authors.forename: L
authors.initials: L
authors.lastname: Titus-Ernstoff
authors.forename: J A
authors.initials: JA
authors.lastname: Baron
authors.forename: B E
authors.initials: BE
authors.lastname: Storer
authors.forename: M
authors.initials: M
authors.lastname: Stampfer
authors.forename: W C
authors.initials: WC
authors.lastname: Willett
mesh_terms: D000368:Aged; D001827:Body Height; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008404:Massachusetts / Q000453:epidemiology; D008875:Middle Aged; D009513:New Hampshire / Q000453:epidemiology; D009765:Obesity / Q000150:complications*; D016017:Odds Ratio; D017698:Postmenopause / Q000502:physiology*; D015203:Reproducibility of Results; D012307:Risk Factors; D011795:Surveys and Questionnaires; D015430:Weight Gain; D015431:Weight Loss; D014922:Wisconsin / Q000453:epidemiology