Risk of breast cancer with menopausal hormone therapy by duration in large observational studies (Mirkin, 2018)
Study Therapy Hazard ratio (95% CITooltip confidence interval)
E3N-EPIC: Fournier et al. (2005)a Transdermal estrogen plus progesterone
    <2 years
    2–4 years
    ≥4 years
0.9 (0.6–1.4)
0.7 (0.4–1.2)
1.2 (0.7–2.0)
Transdermal estrogen plus progestin
    <2 years
    2–4 years
    ≥4 years
1.6 (1.3–2.0)
1.4 (1.0–1.8)
1.2 (0.8–1.7)
Oral estrogen plus progestin
    <2 years
    2–4 years
    ≥4 years
1.2 (0.9–1.8)
1.6 (1.1–2.3)
1.9 (1.2–3.2)
E3N-EPIC: Fournier et al. (2008) Estrogen plus progesterone
    <2 years
    2–4 years
    4–6 years
    ≥6 years
0.71 (0.44–1.14)
0.95 (0.67–1.36)
1.26 (0.87–1.82)
1.22 (0.89–1.67)
Estrogen plus dydrogesterone
    <2 years
    2–4 years
    4–6 years
    ≥6 years
0.84 (0.51–1.38)
1.16 (0.79–1.71)
1.28 (0.83–1.99)
1.32 (0.93–1.86)
Estrogen plus other progestogens
    <2 years
    2–4 years
    4–6 years
    ≥6 years
1.36 (1.07–1.72)
1.59 (1.30–1.94)
1.79 (1.44–2.23)
1.95 (1.62–2.35)
E3N-EPIC: Fournier et al. (2014) Estrogens plus progesterone or dydrogesterone
    <5 years
    ≥5 years
1.13 (0.99–1.29)
1.31 (1.15–1.48)
Estrogen plus other progestogens
    <5 years
    ≥5 years
1.70 (1.50–1.91)
2.02 (1.81–2.26)
Footnotes: a = Oral estrogen plus progesterone was not analyzed because there was a low number of women who used this therapy. Sources: Main: [1] Additional: [2][3][4]
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