Yes, but the increase is small and depends on the type of hormone and how long it is used. Combined hormone therapy (oestrogen plus a progestogen) raises the risk of breast cancer slightly, and the longer it is taken, the larger the increase; oestrogen alone carries a smaller risk and vaginal oestrogen has not raised the risk [1, 5]. For example, out of every 1,000 women who take combined HRT for 5 years from age 50, about 20 more will develop breast cancer by age 69 than among women who do not take hormones [2].
Key points
- Combined HRT (oestrogen plus a progestogen) raises the risk of breast cancer slightly; the longer it is used, the larger the increase [1, 5].
- The real risk is small: out of every 1,000 women who take combined HRT for 5 years from age 50, about 20 more develop breast cancer by age 69 [2].
- Oestrogen alone (for women who have had their womb removed) carries a smaller risk; in one large study it even lowered breast cancer [3, 5].
- Vaginal oestrogen (a vaginal cream or tablet for vaginal dryness) has not raised the risk of breast cancer [1, 5].
- If you have a womb, oestrogen should not be taken on its own; a progestogen protects the womb from cancer [5, 7].
- It has benefits too: it is the most effective treatment for hot flushes and night sweats, and it prevents bone loss [6, 10].
- Decide with your doctor, based on how severe your symptoms are, your age and your own medical history [5, 6].
What is menopausal hormone therapy?
At the menopause, the ovaries stop making enough oestrogen. In many women, the fall in this hormone causes hot flushes, night sweats and vaginal dryness [5, 6]. Menopausal hormone therapy (also called hormone replacement therapy, HRT) means giving the body oestrogen to ease these symptoms [7]. There are two main types:
- Combined (oestrogen plus a progestogen): for women who have a womb. The progestogen (progesterone or a similar medicine) protects the lining of the womb from overgrowth and cancer [7, 8].
- Oestrogen alone: for women whose womb has been removed by surgery [5, 7].
These hormones are taken as tablets or through the skin (patches or gel) [1, 5]. Vaginal oestrogen (a vaginal cream, tablet or ring) is a different kind that is used for vaginal dryness and soreness, and only a very small amount of it reaches the bloodstream [5].
How much does hormone therapy raise the risk of breast cancer?
The largest review brought together information on more than 108,000 women with breast cancer from studies around the world [1]. It found that every type of hormone therapy except vaginal oestrogen raised the risk slightly. The increase was larger with the combined type than with oestrogen alone, and it grew the longer the hormones were used [1]. After stopping, the risk falls, but part of it remains for more than 10 years; use for less than a year added almost no risk [1].
The official UK guideline on the menopause has turned these figures into plain numbers. Without hormone therapy, about 59 out of every 1,000 women develop breast cancer between the ages of 50 and 69 [2]. The table shows how many women hormone therapy started at age 50 adds to this number:
| Type of hormone therapy (from age 50) | 5 years of use | 10 years of use |
|---|---|---|
| Combined (oestrogen plus a progestogen) | About 20 more [2] | About 33 more [2] |
| Oestrogen alone (women without a womb) | About 10 more [2] | About 12 more [2] |
These numbers are averages for women in the UK, and each woman's risk also depends on her other risk factors [5]. With the combined type, taking the progestogen every day of the month carries a slightly higher risk than taking it on only some days of the month [1, 5].
In a large American study that randomly assigned women to combined hormones or a dummy pill, about 8 more of every 10,000 women taking hormones developed breast cancer each year [4]. The UK guideline describes the increase in the risk of dying from breast cancer with combined HRT as "very small", and in the same American study, after more than 20 years of follow-up, no clear difference in deaths from breast cancer was seen [3, 5].
How do oestrogen alone and vaginal oestrogen differ?
Oestrogen alone: in the same large American study, more than 10,000 women who had had their womb removed were randomly given oestrogen alone or a dummy pill. After more than 20 years, breast cancer and deaths from it were lower in the oestrogen group [3]. Studies that compared women who chose to use it with other women have shown a small increase [1]. The UK guideline concludes that oestrogen alone causes very little or no increase in the risk of breast cancer [5].
Vaginal oestrogen: vaginal creams, tablets or rings, used for dryness, soreness and pain during sex, did not raise the risk of breast cancer in the largest review [1]. Only a very small amount reaches the bloodstream, and the UK guideline recommends it for these symptoms, even for women who are also taking tablets, patches or gel [5].
Hormone therapy and womb and ovarian cancer
Womb cancer: if you have a womb, oestrogen on its own makes the lining of the womb grow too much and raises the risk of womb (endometrial) cancer [7, 8]. This is why women who have a womb are given oestrogen together with a progestogen [5]. Out of every 1,000 women aged 50 to 54 who have a womb, about 4 develop womb cancer over 5 years; oestrogen alone adds about 7 to this number, whereas combined HRT with a progestogen taken every day even lowers the risk slightly [2]. If the progestogen is taken on only some days of the month, the risk rises slightly [2, 5].
Bleeding is common in the first 6 months of hormone therapy, but tell your doctor promptly about unexpected bleeding after that [5]. See: Symptoms of womb (endometrial) cancer.
Ovarian cancer: hormone therapy raises the risk of ovarian cancer very slightly. Out of every 1,000 women who take hormones for about 5 years from age 50, about one more develops ovarian cancer [2, 9]. See: Symptoms of ovarian cancer.
Other benefits and risks of hormone therapy
Hormone therapy is the most effective treatment for hot flushes and night sweats [6]. In a review of 24 studies, it cut the number of hot flushes by about three-quarters and also made them less severe [10]. It also prevents bone loss and fractures [5, 6].
- Life expectancy: according to the UK guideline, hormone therapy is unlikely to change life expectancy [5].
- Blood clots: hormone tablets raise the risk of blood clots, but patches and gel do not [5].
- Stroke: with tablets the risk rises, especially with higher doses and longer use; with oestrogen through the skin it is unlikely to rise [5].
- The age at which you start matters: for women under 60, or within 10 years of the menopause, who have troublesome symptoms, the benefits usually outweigh the risks; starting later brings fewer benefits and more risks [6].
What should I do? One important step: weigh the benefits and risks for yourself with your doctor
- 1
Tell your doctor about your symptoms
If hot flushes, night sweats or poor sleep are disrupting your life, tell your doctor. Hormone therapy is offered for these symptoms, and for women who do not want or cannot take hormones there are other options, such as cognitive behavioural therapy [5].
- 2
Tell your doctor about your own and your family's medical history
A history of breast cancer, blood clots, stroke or heart disease in you or your family matters when choosing a treatment [5, 11]. See: Is cancer hereditary?
- 3
The lowest effective dose and regular reviews
If you start hormones, use the lowest dose that works; talk about how long you will take them from the start, and weigh the benefits and risks again with your doctor after 3 months and then every year [5].
- 4
Do not forget screening
Keep up to date with recommended screening, including mammograms [5]. See: At what age should mammograms start? and Symptoms of breast cancer.
Frequently asked questions
If I take hormones for less than a year, is there a breast cancer risk?
In the largest review, use for less than a year added almost no risk. The risk rises with longer use [1].
Does the risk go away after I stop?
Are patches or gel safer for the breasts than tablets?
Does vaginal oestrogen cream also carry a breast cancer risk?
In the largest review, vaginal oestrogen did not raise the risk of breast cancer, and only a very small amount reaches the bloodstream [1, 5]. If you have had breast cancer, non-hormonal moisturisers and lubricants are suggested first; if they are not enough, discuss vaginal oestrogen with your doctor [5].
I have had breast cancer. Can I take menopausal hormone therapy?
How many years can I keep taking hormone therapy?
Talk with your doctor about how long you will take it from the start, and at every review weigh the benefits and risks of continuing again [5]. Longer use is for a clear reason, such as hot flushes that continue, with a shared decision between you and your doctor and regular reviews [6]. Remember that the risk of breast cancer rises with longer use [1] and that symptoms may come back after stopping [5].
Details of the evidence (for physicians)
For physicians
Collaborative Group meta-analysis (Lancet 2019; individual participant data, 108,647 postmenopausal women with breast cancer, mean age 65 years). Current users, years 1–4: oestrogen-progestagen RR 1.60 (1.52 to 1.69) and oestrogen-only 1.17 (1.10 to 1.26); years 5–14: 2.08 (2.02 to 2.15) and 1.33 (1.28 to 1.37); daily progestagen 2.30 (2.21 to 2.40) vs intermittent 1.93 (1.84 to 2.01). Vaginal oestrogen RR 1.09 (0.97 to 1.23). Risks were much greater for ER-positive tumours, similar for starting at ages 40 to 59, and attenuated by starting after age 60 or by adiposity; after stopping, some excess persisted for more than 10 years and was small after less than 1 year of use. Absolute risk for 5 years of use from age 50 in women of average weight: 20-year incidence (ages 50–69) from 6.3% to 8.3% with daily progestagen (one case per 50 users), 7.7% with intermittent progestagen (one in 70) and 6.8% with oestrogen-only (one in 200); about twice as great with 10 years of use [1].
WHI (randomised placebo-controlled trials). CEE 0.625 mg + MPA 2.5 mg daily in 16,608 women with a uterus: in the main report (mean 5.2 years), HR for invasive breast cancer 1.26 (1.00 to 1.59), i.e. 8 extra cases per 10,000 person-years; colorectal cancer 0.63 (0.43 to 0.92) and endometrial cancer 0.83 (0.47 to 1.47) [4]. Long-term follow-up (median cumulative follow-up more than 20 years, 27,347 women): CEE+MPA breast cancer incidence 584 vs 447 cases (annualised 0.45% vs 0.36%; HR 1.28; 1.13 to 1.45) with no significant difference in breast cancer mortality (HR 1.35; 0.94 to 1.95); CEE alone in 10,739 women with prior hysterectomy: 238 vs 296 cases (0.30% vs 0.37%; HR 0.78; 0.65 to 0.93) and breast cancer deaths 30 vs 46 (HR 0.60; 0.37 to 0.97) [3]. Mention in counselling that the WHI result for CEE alone differs from the observational data [1, 3].
NICE NG23 (2024 update; discussion aid, per 1,000 women). Breast cancer at ages 50–69: no HRT 59; combined 5 years 79 (+20) and 10 years 92 (+33); oestrogen-only 5 years 69 (+10) and 10 years 71 (+12). Early menopause (ages 40–44): combined for 10 years from age 40, 51 vs 33 (ages 40–59). Endometrial cancer over 5 years (ages 50–54): baseline 4; oestrogen-only in women with a uterus 11 (+7); continuous combined 1 (−3); sequential combined 8 (+4). Ovarian cancer over 5 years: 1 vs 2 (+1) [2]. NICE: the breast cancer risk with combined HRT rises with duration, is higher with current than past use and persists at least 10 years after stopping; the increase in breast cancer mortality is "very small"; oestrogen-only causes "very little or no increase"; a difference for micronised progesterone or dydrogesterone versus other progestogens has not been established. VTE risk is increased with oral HRT and not with transdermal HRT; prefer transdermal HRT in people at increased VTE risk, including those with a BMI over 30 [5].
Endometrium and ovary. Cochrane 2025 (72 trials, 40,652 women): unopposed oestrogen vs placebo, endometrial hyperplasia at 1 year OR 5.86 (4.09 to 8.40) and after 1 year 8.97 (6.78 to 11.87); continuous combined vs placebo OR 0.51 (0.08 to 3.38); too few endometrial cancer events to draw conclusions [8]. Ovary (Collaborative Group, 52 studies, 12,110 cases in prospective studies): current use for less than 5 years RR 1.43 (1.31 to 1.56), current or recent use 1.37 (1.29 to 1.46), definitely increased only for serous and endometrioid types; 5 years of use from about age 50 gives about 1 extra cancer per 1,000 users and 1 extra death per 1,700 users [9].
Benefit and patient selection. Cochrane (24 trials, 3,329 women): oral HRT reduced weekly hot flush frequency by 75% (64.3 to 82.3%) relative to placebo and also reduced severity (OR 0.13) [10]. NAMS 2022 position statement: the most effective treatment for vasomotor symptoms and the genitourinary syndrome of menopause; for women younger than 60 or within 10 years of menopause onset without contraindications, the benefit-risk ratio is favourable for bothersome symptoms and prevention of bone loss, and less favourable thereafter; longer durations only for documented indications, with shared decision-making and periodic re-evaluation; for GSM, low-dose vaginal oestrogen [6]. NICE: lowest effective dose, discuss treatment duration at the outset, review at 3 months and then annually [5]. History of breast cancer: stop systemic HRT at diagnosis and do not routinely offer it; only in exceptional circumstances with severe symptoms after a discussion of the risks (NICE NG101) [11].
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References
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Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
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