Endometrial cancer and menopausal hormone therapy in the National Institutes of Health-AARP Diet and Health Study cohort.
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.
Lacey
James V
JV
Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA. jimlacey@nih.gov
Leitzmann
Michael F
MF
Chang
Shih-Chen
SC
Mouw
Traci
T
Hollenbeck
Albert R
AR
Schatzkin
Arthur
A
Brinton
Louise A
LA
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
D004967:Estrogens; D011372:Progestins