title: Endometrial cancer and menopausal hormone therapy in the National Institutes of Health-AARP Diet and Health Study cohort.
abstract: BACKGROUND
  Menopausal hormone therapy formulations for women without hysterectomy have included estrogen plus progestin for years, but endometrial cancer risks associated with the use of sequential and continuous estrogen-plus-progestin regimens remain unclear.
  
  
  METHODS
  The National Institutes of Health-AARP Diet and Health Study included 73,211 women who were ages 50 years to 71 years at baseline and who completed 2 questionnaires (1995-1996 and 1996-1997). Linkage to state cancer registries and mortality indices identified 433 incident endometrial cancers through 2000. Using proportional hazards regression, the authors estimated relative risks (RRs) and 95% confidence intervals (95% CIs) relative to never-use of hormone therapy.
  
  
  RESULTS
  In 51,312 women who never used hormones or only used estrogen-plus-progestin regimens at doses consistent with current practice, neither sequential estrogen plus progestin (daily estrogen plus progestin for 10-14 days per cycle: RR, 0.74; 95% CI, 0.39-1.40) nor continuous estrogen plus progestin (daily estrogen plus progestin for >/=20 days per cycle: RR, 0.80; 95% CI, 0.55-1.15) had any statistically significant association with endometrial cancer. Long durations (>/=5 years) of sequential regimen use (RR, 0.79; 95% CI, 0.38-1.66) and of continuous regimen use (RR, 0.85; 95% CI, 0.53-1.36) were not associated with endometrial cancer.
  
  
  CONCLUSIONS
  Confirmation that these estrogen-plus-progestin regimens neither increase nor decrease the risk of endometrial cancer could influence menopausal symptom management for women who are considering estrogen-plus-progestin therapy.
authors.affiliation: Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA. jimlacey@nih.gov
authors.forename: James V
authors.initials: JV
authors.lastname: Lacey
authors.forename: Michael F
authors.initials: MF
authors.lastname: Leitzmann
authors.forename: Shih-Chen
authors.initials: SC
authors.lastname: Chang
authors.forename: Traci
authors.initials: T
authors.lastname: Mouw
authors.forename: Albert R
authors.initials: AR
authors.lastname: Hollenbeck
authors.forename: Arthur
authors.initials: A
authors.lastname: Schatzkin
authors.forename: Louise A
authors.initials: LA
authors.lastname: Brinton
mesh_terms: D000368:Aged; D015331:Cohort Studies; D004032:Diet; D016889:Endometrial Neoplasms / Q000453:epidemiology*; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D017698:Postmenopause; D011372:Progestins / Q000008:administration & dosage*; D011446:Prospective Studies; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D016387:Women's Health
chemical_list: D004967:Estrogens; D011372:Progestins