title: Combined estrogen and progestin hormone replacement therapy in relation to risk of breast cancer in middle-aged women.
abstract: OBJECTIVE
  To determine the risk of breast cancer in relation to the use of combined estrogen and progestin hormone replacement therapy (HRT).
  
  
  METHODS
  A population-based case-control study.
  
  
  METHODS
  The general female population of King County in western Washington State.
  
  
  METHODS
  Middle-aged (50 to 64 years) women, including 537 patients with incident primary breast cancer diagnosed between January 1, 1988, and June 30, 1990, who were ascertained through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results cancer registry and 492 randomly selected control women without a history of breast cancer.
  
  
  METHODS
  Breast cancer risk in relation to use of menopausal hormones.
  
  
  RESULTS
  Menopausal hormones of some type had been used by 57.6% of breast cancer cases and 61.0% of comparison women. The women who had ever taken combined estrogen-progestin HRT, representing 21.5% of cases and 21.3% of controls, were not at increased risk of breast cancer (relative odds [RO] = 0.9; 95% confidence interval [CI], 0.7 to 1.3). Compared with nonusers of menopausal hormones, those who used estrogen-progestin HRT for 8 or more years had, if anything, a reduced risk of breast cancer (RO = 0.4; 95% CI, 0.2 to 1.0).
  
  
  CONCLUSIONS
  On the whole, the use of estrogen with progestin HRT does not appear to be associated with an increased risk of breast cancer in middle-aged women. Nonetheless, since the use of combined estrogen-progestin HRT has only recently become prevalent, future investigations must assess whether breast cancer incidence is altered many years after estrogen-progestin HRT has been initiated, particularly among long-term users.
authors.affiliation: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Stanford
authors.forename: N S
authors.initials: NS
authors.lastname: Weiss
authors.forename: L F
authors.initials: LF
authors.lastname: Voigt
authors.forename: J R
authors.initials: JR
authors.lastname: Daling
authors.forename: L A
authors.initials: LA
authors.lastname: Habel
authors.forename: M A
authors.initials: MA
authors.lastname: Rossing
mesh_terms: D001943:Breast Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D016022:Case-Control Studies; D004359:Drug Therapy, Combination; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D004967:Estrogens / Q000009:adverse effects* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D011372:Progestins / Q000009:adverse effects* / Q000627:therapeutic use; D016016:Proportional Hazards Models; D012307:Risk Factors
chemical_list: D004967:Estrogens; D011372:Progestins