Hormone replacement therapy and the risk of death from breast cancer: a systematic review.
OBJECTIVE
Recent studies have shown an increased relative risk of breast cancer with hormone replacement therapy for > or = 5 years. However, tumors in hormone replacement therapy users are more likely to be localized and of a favorable histologic condition. Our objective was to determine the effects of hormone replacement therapy on the risk of death from breast cancer.


METHODS
We searched the literature to identify studies that addressed hormone replacement therapy and breast cancer death among healthy hormone replacement therapy users compared with nonusers. We included randomized controlled trials and cohort and case-control studies with adequate controls and retrievable risk estimates.


RESULTS
Ten observational studies met the inclusion criteria; these studies varied widely with regard to population, choice of control group, ascertainment of exposure and outcome, and adjustment for potential confounders.


CONCLUSIONS
Most studies showed a reduced risk of death from breast cancer in hormone replacement therapy users compared with nonusers. In a few studies, this risk reduction was attenuated after prolonged use or prolonged duration of follow-up. Limited information on recency of use, dose, or use of combined hormone replacement therapy was available.
Nanda
Kavita
K
Family Health International, Durham, NC, USA.
Bastian
Lori A
LA
Schulz
Kenneth
K
D001943:Breast Neoplasms / Q000401:mortality*; D016022:Case-Control Studies; D015331:Cohort Studies; D015914:Estrogen Replacement Therapy / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment