Postmenopausal hormone therapy and the risks of coronary heart disease, breast cancer, and stroke.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing findings from previously published randomized trials without a systematic review protocol.
PubMed 25321418 · doi:10.1055/s-0034-1384624
What was done
This review summarized findings from the Women's Health Initiative (WHI) randomized trials assessing conjugated equine estrogens (CEE) alone and CEE combined with medroxyprogesterone acetate (MPA). It examined coronary heart disease (CHD), invasive breast cancer, and stroke risk, specifically focusing on the timing of therapy initiation, treatment adherence, participant characteristics, and prerandomization biomarkers.
What was found
Combined CEE plus MPA increased CHD risk early after initiation, with the elevated risk dissipating after several years of treatment. Invasive breast cancer risk rose over the treatment duration to an approximate threefold increase after 5 years of adherence, with higher risk observed in women initiating therapy at or near menopause compared to those with a longer gap time. Stroke risk did not vary meaningfully by initiation timing; both CEE alone and combined therapy produced an approximate 50% increase in ischemic strokes.
Why it matters
The paper clarifies that hormone therapy risk profiles differ substantially by outcome and timing: CHD risk is early and transient, breast cancer risk compounds with duration and early initiation, and ischemic stroke risk remains elevated regardless of timing.
Limits
The abstract provides relative estimates without sample sizes, absolute risk differences, exact p-values, or confidence intervals. As a narrative review, it does not apply systematic review methodology, and the biological pathways mediating these outcomes remain incompletely understood.
Cited by
- context Estrogen replacement therapy that is not paired with progesterone increases the risk of stroke and heart attack.