Influence of estrogen plus progestin on breast cancer and mammography in healthy postmenopausal women: the Women's Health Initiative Randomized Trial.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 12824205 · doi:10.1001/jama.289.24.3243
What was done
The Women's Health Initiative randomized 16,608 postmenopausal women aged 50 to 79 years with an intact uterus to receive daily combined conjugated equine estrogens (0.625 mg) plus medroxyprogesterone acetate (2.5 mg) or placebo across 40 clinical centers between 1993 and 1998. Participants underwent annual screening mammography and clinical breast examinations. The study assessed breast cancer incidence, tumor characteristics (histology, grade, size, stage), and the frequency of abnormal mammograms using intent-to-treat analyses.
Cited by
- supports In the Women's Health Initiative trial, the conjugated equine estrogen (CEE) plus medroxyprogesterone acetate (MPA) arm was stopped early at ~5.5 years with a 0.1% higher absolute risk (5 vs 4 cases per 1,000 women) of breast cancer compared to placebo, with no difference in breast cancer mortality.