Table 2 Risk of breast cancer (95% CI) over time in women receiving estrogen-only (CEE) or estrogen (CEE) plus progestin (MPA) menopausal hormone treatment (MHT) in the Women’s Health Initiative (WHI) study
From: Progesterone from ovulatory menstrual cycles is an important cause of breast cancer
Study | Overall BC risk | Cumulative BC risk | Statistical analysis |
|---|---|---|---|
WHI CEE (Anderson 2004) [117] Mean FU 6.8 yr | Overall HR 0.77 (0.57–1.06) | Cumulative Hazard (8 yr) HR 0.77 (0.59–1.01) | HR (adjusted) vs Placebo |
WHI CEE (Chlebowski 2020) [118] Median FU 16.2 yr |  | Cumulative Hazard (22 yr) HR 0.78 (0.65–0.93) | P = 0.005 versus placebo |
WHI CEE/MPA (Rossouw 2002) [65] Mean FU 5.2 yr | Overall HR 1.26 (0.83–1.92) | Subgroup FU ≥ 10 yr HR 1.81 (0.60–5.43) | HR (adjusted) versus Placebo Z score for trend 2.56 |
WHI CEE/MPA (Hodis 2018) [66] Mean FU 5.6 yr | HT naïve patients (75% of cohort) HR 1.02 (0.77–1.36)* | Subgroup with prior HT HR 1.96 (1.17–3.27) | HR versus Placebo Difference naïve vs prior HT: P = 0.027 |
WHI CEE/MPA (Chlebowski 2020) [118] Median FU 18.9 yr |  | Cumulative Hazard (22 yr) HR 1.28 (1.13–1.45) | P < 0.001 versus placebo |
Study | BC mortality | Â | Â |
WHI CEE (Manson 2017) [68] Cumulative FU 18 yr | Overall HR 0.55 (0.33–0.92) |  | P = 0.02 versus placebo |
WHI CEE/MPA (Manson 2017) [68] Cumulative FU 18 yr | Overall HR 1.44 (0.97–2.15) |  | HR (adjusted) versus Placebo |