Benefits and harms of systemic estrogen-only MHT
In postmenopausal individuals without a uterus, systemic estrogen-only MHT reduces the risk of:
- fractures of all types (56 fewer per 10 000 person years)
- hip fractures (6 fewer per 10 000 person years)
- diabetes mellitus (19 fewer per 10 000 person years)
- self-reported vasomotor symptoms (1205 fewer per 10 000 person years).
In postmenopausal individuals without a uterus, systemic estrogen-only MHT increases the risk of:
- stroke (11 additional cases per 10 000 person years)
- venous thromboembolism (DVT or PE) (11 additional cases per 10 000 person years)
- gallbladder disease (33 additional cases per 10 000 person years)
- self-reported urinary incontinence (1261 additional cases per 10 000 person years).
Randomised controlled trial data indicate that risk of breast cancer is not significantly increased (and may reduce during long-term follow-up) in individuals taking estrogen-only MHT1. In contrast, prospective observational studies suggest an increase in breast cancer risk, but it is not known if the association is causal.
Systemic estrogen-only MHT does not significantly increase risk of coronary heart disease, dementia, lung cancer, colorectal cancer or all-cause mortality.