Then and Now: What We Have Learned From the WHI.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing findings from the Women's Health Initiative and related literature.
PubMed 41379766 · doi:10.1210/clinem/dgaf638
What was done
The authors conducted a narrative review of the Women's Health Initiative (WHI) literature to assess the risks and benefits of menopausal hormone therapy (MHT) in postmenopausal women. A structured PubMed search of English-language clinical trials, observational studies, and systematic reviews covered bone health, cardiovascular and metabolic disease, cognitive outcomes, and breast, endometrial, ovarian, and colorectal cancers.
What was found
The abstract reports directional outcomes without numerical effect estimates or confidence intervals. Both conjugated equine estrogen-medroxyprogesterone acetate (CEE-MPA) and CEE-only regimens significantly reduced hip, vertebral, and total fracture risk, with additional benefit from calcium and vitamin D co-administration. Cardiovascular outcomes depended on timing: initiating MHT before age 60 or within 10 years of menopause showed potential benefit, whereas initiation at age 65 or older increased risks of coronary events and stroke. CEE-MPA increased invasive breast cancer incidence (particularly in prior users), while CEE-only showed a marginal non-significant reduction. Both regimens lowered colorectal cancer incidence during active treatment. Early MHT had no effect on cognitive function, whereas late initiation increased dementia risk.
Why it matters
This synthesis reinforces the timing hypothesis for menopausal hormone therapy, clarifying that clinical decisions should be individualized based on age, time since menopause, and specific drug regimen rather than applying broad generalizations.
Limits
The review relies on narrative synthesis rather than a formal systematic review or meta-analysis, and the abstract provides no exact quantitative metrics. Findings primarily reflect specific WHI regimens (oral CEE with or without MPA) and may not fully generalize to newer formulations, transdermal administration, or lower-dose options.