title: Dose of progestin in postmenopausal-combined hormone therapy and risk of endometrial cancer.
abstract: OBJECTIVE
  We studied the impact of progestin dose on this risk. The pattern and number of days per month that progestin is given in postmenopausal combined hormone therapy appears to affect endometrial cancer risk. We assessed the impact of progestin dose on this risk.
  
  
  METHODS
  A population-based, case-control study included 647 cases with endometrial cancer and 1209 controls.
  
  
  RESULTS
  Among users of estrogen with medroxyprogesterone acetate (MPA) 10 to 24 days/month, women who took >100 mg/month had an endometrial cancer risk that was equal to that of hormone nonusers (95% CI 0.6-1.7). The corresponding relative risk was 0.8 (95% CI 0.5-1.5) in those who used a lower monthly MPA dose for 10 to 24 days/month. Among users of a continuous combined hormone regimen, the risk of endometrial cancer was low relative to hormone nonusers, regardless of MPA dose.
  
  
  CONCLUSIONS
  Among the combined hormone regimens most commonly used by postmenopausal women today, MPA monthly dose bears little or no relation to endometrial cancer risk.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Public Health Sciences, University of Washington, 325 9th Avenue, Seattle, WA 98115, USA. reeds@u.washington.edu
authors.forename: Susan D
authors.initials: SD
authors.lastname: Reed
authors.forename: Lynda F
authors.initials: LF
authors.lastname: Voigt
authors.forename: Shirley A A
authors.initials: SA
authors.lastname: Beresford
authors.forename: Deirdre A
authors.initials: DA
authors.lastname: Hill
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Doherty
authors.forename: Noel S
authors.initials: NS
authors.lastname: Weiss
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003271:Contraceptive Agents, Female / Q000008:administration & dosage*; D016889:Endometrial Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D015914:Estrogen Replacement Therapy / Q000009:adverse effects; D005260:Female; D006801:Humans; D017258:Medroxyprogesterone Acetate / Q000008:administration & dosage*; D008875:Middle Aged; D011372:Progestins; D018570:Risk Assessment
chemical_list: D003271:Contraceptive Agents, Female; D011372:Progestins; D017258:Medroxyprogesterone Acetate