HRT and Breast Cancer Risk

What is HRT?

Hormone replacement therapy (HRT) replaces the oestrogen and progesterone that decline during menopause. It is one of the most effective treatments for hot flushes, night sweats, mood disturbance and vaginal dryness. In the UK, around 1 in 7 women aged 45–55 take HRT at any given time.

Does HRT cause breast cancer?

HRT is associated with a small increased breast cancer risk — but the size of that risk depends on the type of HRT, how long it is taken, and individual risk factors. The relationship is frequently misreported in headlines. NHS and NICE guidance is clear that for most women with significant menopausal symptoms, the benefits outweigh the small risk.

Risk by HRT type

• Oestrogen-only HRT: little to no increased breast cancer risk. Only prescribed to women who have had a hysterectomy.
• Combined HRT (oestrogen + progestogen): small increased risk that grows with duration of use. The most commonly prescribed type.
• Vaginal or topical oestrogen: very low doses absorbed locally. No increased breast cancer risk.
• Body-identical HRT (micronised progesterone): emerging evidence suggests lower risk than synthetic progestogens; long-term data continuing to accumulate.

Absolute risk — putting numbers in context

When studies report a "30% increased risk" from HRT, this is a relative increase. In absolute terms, around 2 in every 100 UK breast cancers are thought to be associated with HRT use. For a woman in her 50s taking combined HRT for 5 years, the estimated absolute increase is approximately 4 extra cases per 1,000 women — similar to the absolute risk increase from drinking one glass of wine per day, or from being overweight after menopause.

How long does increased risk persist after stopping?

The raised risk associated with combined HRT begins to fall once HRT is stopped, and returns close to baseline within approximately 5 years. Women who took HRT for less than one year have very little measurable lasting increase. The NHS advises using the lowest effective dose for the shortest time that manages symptoms.

Can I take HRT after breast cancer?

For most breast cancer survivors, combined systemic HRT is not recommended because oestrogen can stimulate hormone receptor-positive cells. However, vaginal oestrogen for local symptoms (dryness, discomfort) is generally considered lower risk and is used by many survivors with specialist agreement. This is an individual clinical decision to make with your oncologist or breast care team.

While you weigh this decision — millions of women have no choice at all

The debate about HRT and breast cancer risk is a conversation that happens from a position of significant privilege. Women in the UK have access to GPs, specialist menopause clinics, and the ability to weigh nuanced medical decisions with a qualified doctor. In low-income countries across the developing world — the communities where Breast Cancer Awareness works — most women have never had a breast examination. Breast cancer there is almost always found at Stage III or Stage IV, when survival chances fall from 98% to 26%. The difference between those two outcomes is not biology. It is access to screening, education and timely diagnosis. A donation of £25 funds one complete breast cancer screening for a woman who would otherwise have none.