title: Endometrial cancer risk in estrogen users after switching to estrogen-progestin therapy.
abstract: OBJECTIVE
  It is unknown whether postmenopausal unopposed estrogen users are better off, in terms of endometrial cancer risk, switching to a combined estrogen-progestin regimen or stopping hormone use altogether.
  
  
  METHODS
  We analyzed data from a series of three population-based case-control studies in western Washington state during 1985-1999, comparing proportions of "switchers" and "stoppers" in cases and controls. We also assessed whether the risk of endometrial cancer in either group of former unopposed estrogen users returned to that of never users.
  
  
  RESULTS
  After multivariate adjustment using unconditional logistic regression, women who switched to a combined regimen with a progestin added for at least ten days/month (37 cases, 47 controls) had half the risk of endometrial cancer of women who stopped hormone use altogether (86 cases, 78 controls) (adjusted odds ratio = 0.5, 95% confidence interval: 0.3-1.1). Most subgroups of former users, whether they switched or stopped, had some increased risk of endometrial cancer compared to never users.
  
  
  CONCLUSIONS
  Results from this study suggest that unopposed estrogen users may reduce their risk of endometrial cancer more by switching to a combined regimen with progestin added for at least ten days/month than by stopping hormone use altogether.
authors.affiliation: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98195, USA. jchubak@u.washington.edu
authors.forename: Jessica
authors.initials: J
authors.lastname: Chubak
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Doherty
authors.forename: Kara L
authors.initials: KL
authors.lastname: Cushing-Haugen
authors.forename: Lynda F
authors.initials: LF
authors.lastname: Voigt
authors.forename: Babette S
authors.initials: BS
authors.lastname: Saltzman
authors.forename: Deirdre A
authors.initials: DA
authors.lastname: Hill
authors.forename: Shirley A A
authors.initials: SA
authors.lastname: Beresford
authors.forename: Noel S
authors.initials: NS
authors.lastname: Weiss
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D016001:Confidence Intervals; D004334:Drug Administration Schedule; D016889:Endometrial Neoplasms / Q000139:chemically induced* / Q000473:pathology; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D004967:Estrogens / Q000008:administration & dosage* / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D011372:Progestins / Q000008:administration & dosage* / Q000009:adverse effects*; D012307:Risk Factors
chemical_list: D004967:Estrogens; D011372:Progestins