HRT and breast cancer risk: what the evidence says

HRT and breast cancer risk, in absolute numbers

This is not medical advice — it is general information based on what you searched for that may help.

General information based on published sources and the symptoms you searched for. This isn't medical or legal advice, a diagnosis or a treatment plan. Please consult a doctor about your own symptoms. If your symptoms are severe or sudden, seek urgent care.

This page may not apply to you if:

This page describes population-level risk for people with no personal history of breast cancer; a personal or strong family history changes the picture and needs a specialist discussion

Breast cancer risk is usually the first question women ask about hormone therapy, and the honest answer depends on which type of HRT you're asking about. NICE guideline NG23 draws a clear distinction between combined HRT (estrogen plus a progestogen) and estrogen-only HRT (used by people who have had a total hysterectomy).

Combined HRT (estrogen plus progestogen)

Risk increases with combined HRT, and that increase rises with how long you use it, is higher while currently taking it than after stopping, and persists for at least 10 years after stopping even though it declines over that time.
There is also a very small increase in risk of death from breast cancer with combined HRT.
The regimen matters: sequential combined HRT (progestogen for part of the cycle) carries a lower risk than continuous combined HRT (progestogen every day) — though both carry more risk than no HRT.
There currently isn't enough evidence to say whether micronised progesterone or dydrogesterone change this risk compared with other progestogens.

Estrogen-only HRT (after a total hysterectomy)

NICE guidance states there is very little or no increase in breast cancer risk, and little or no increase in breast cancer mortality, with estrogen-only HRT.
Risk is similar between oestradiol and conjugated equine oestrogen formulations.

It's not just about HRT

Breast cancer risk varies from person to person based on factors that have nothing to do with hormone therapy — family history, genetics, age, alcohol use, body weight, and others all play a role. That's why this is a conversation to have with a clinician who knows your personal and family history, not a single number that applies to everyone equally.

NICE's own patient materials include a discussion aid with the actual number of additional breast cancer cases per 1,000 people over 5- and 10-year periods, broken down by HRT type — ask your clinician to go through this with you rather than relying on a headline percentage.

Where this fits with the 2025–2026 label changes

The FDA's 2025–2026 boxed-warning changes removed breast cancer language from the boxed warning on several products — see the FDA boxed warning change, explained for what changed, what stayed, and where medical societies disagree about whether that was the right call.

Prepare for your appointment

If breast cancer risk makes you want to weigh non-hormonal alternatives too, see our Does It Work? evidence directory for what's actually supported. Organize these questions in our treatment conversation builder before your appointment:

Based on NICE's discussion aid, how many additional breast cancer cases per 1,000 people does my specific HRT option (type, route, and duration) actually represent?
Given my personal and family history, does a combined or estrogen-only option change this calculation for me?

Where are you right now?

Still tracking

Not sure if your symptoms fit? Start tracking your daily patterns.

Log and spot your patterns with the symptom checklist →

Ready to talk to a doctor

Have an upcoming appointment? Bring structured questions and your history.

Prepare your 10-minute doctor appointment questions →

Already on treatment

Evaluating your response or wondering what to adjust next?

Explore evidence-graded treatment and lifestyle options →

Questions people ask

Does HRT cause breast cancer?

The evidence shows an association, not a simple yes/no. NICE guidance states combined HRT (estrogen plus a progestogen) increases breast cancer risk, with the increase rising the longer you use it. Estrogen-only HRT, used by people who have had a hysterectomy, shows very little or no increase in breast cancer risk.

Does the type of combined HRT change the risk?

Yes, somewhat. NICE guidance notes that sequential combined HRT (progestogen for part of the cycle) carries a lower breast cancer risk than continuous combined HRT (progestogen every day), though both carry a higher risk than taking no HRT at all. There isn't yet enough evidence to say whether micronised progesterone changes this risk compared with other progestogens.