HRT risk picker

You want a figure for the appointment. In a group of 1,000 women, how many more are diagnosed with breast cancer, a blood clot or a stroke if they take the HRT you are considering?

These counts come from the NICE NG23 discussion aid (November 2024), the MHRA drug safety update of August 2019 for sequential and continuous combined HRT, and NICE Table 1 for clots and stroke by route. Benefits, and the longer account of these risks, are in HRT risks in plain numbers.

Licensed doses are assumed. The NICE NG23 recommendations cover women with no personal history of breast cancer, stroke or a clot in a vein. The result is a group average, not a prediction for one woman.

Show extra cases

Choose type, route, years and a starting age

Choose oestrogen-only, sequential combined, or continuous combined HRT. Then choose a tablet or a patch or gel, 5 or 10 years, and the age band at the start. Breast cancer figures follow the discussion aid from age 50 to 69. The age band adds context from the Menopause Society and leaves those counts unchanged.

A combined patch for five years, starting at 52

At 52, she is within the age range the chart covers. On that chart, 79 women develop breast cancer by 69. That is 20 more than the 59 with no HRT. Sequential and continuous combined HRT share this row.

The MHRA update starts from another baseline: about 63 diagnoses between 50 and 69 among women who never used HRT. Sequential combined HRT for 5 years means about 14 extra cases above that baseline. Continuous combined HRT is about 20 extra cases over the same 5 years. Adding the NICE extra to the MHRA extra would count the same women twice.

For clots, Table 1 says VTE risk is not increased with transdermal HRT. The 2024 table does not give clot counts by route. The stroke count for this patch example covers ages 50 to 54 across 5 years. In that span, 3 women with no HRT have a stroke. An increase is unlikely when oestrogen is absorbed through the skin. For transdermal combined HRT the difference is too small to show in a group this size, and it is not statistically significant.

Combined tablets for ten years

The NICE combined row moves to 92 by age 69, which is 33 more than with no HRT. The MHRA update says extra cases up to age 69 roughly double when use lasts 10 years, so about 14 sequential cases become about 28. With that doubling, continuous combined HRT is about 40 extra cases. This example uses the sequential figure.

Table 1 says VTE risk is increased with oral HRT, and greater with a tablet than with a patch or gel. An older chapter of NG23 pooled tablets with transdermal HRT and estimated about 9 extra clots in the first year, and about 10 over five years. Use those pooled figures for a tablet. The 2024 table keeps the routes separate and does not give a number.

Stroke risk increases with oral oestrogen, more so at a higher dose and when use runs past 5 years. The baseline risk under 60 is very low. Stroke counts in the aid stop at the 5-year window above. For oral oestrogen-only HRT in that five-year span, 4 women have a stroke. That is one more than the 3 women with no HRT.

Oestrogen-only HRT, by type

On the same NICE chart, 69 of 1,000 have breast cancer after 5 years of oestrogen-only HRT, 10 more than with no HRT, and 71 after 10 years, 12 more. The MHRA 5-year extra is about 5. At 10 years that extra is approximately doubled, against the baseline of 63. Tablets and patches use the same breast cancer figures.

What the age band is for

The breast cancer counts above cover ages 50 to 69. Choosing 45 to 49, 55 to 59, or 60 or over leaves those counts in place.

For healthy women under 60, or within 10 years of menopause, who have bothersome symptoms, the Menopause Society 2022 note says the benefits of hormone therapy generally outweigh the risks. Ages 45 to 54 match that description when the last period was within the past 10 years.

Ages 55 to 59 are still under 60, so that sentence can still apply. If menopause began more than 10 years earlier, the note calls the balance less favourable. The Menopause Society describes a start at 60 or later as less favourable, because absolute risks of heart disease, stroke, blood clots and dementia are higher.

If periods stopped before 45, the early menopause guide explains how long HRT usually continues. The age choices here start at 45.

How these estimates were built

The counts are population averages from the November 2024 discussion aid, from Table 1, from the MHRA 2019 update, and from that older pooled VTE chapter. This is general information. The decision to start or stop HRT rests with the clinician who knows your history. Our editorial policy sets out how health claims on this site are sourced.

My take

I would start with the NICE breast cancer figure, then put the MHRA figure under it, because only the MHRA figure separates sequential from continuous combined HRT. I would judge clots and stroke by tablet versus patch before comparing 5 years with 10. I would mention the starting age in the appointment, and I would skip any breast cancer total outside the 50 to 69 age range.

Related reading

Forms, schedules and who is usually offered which one are in hormone replacement therapy for menopause. The hormone therapy topic lists those guides. The bioidentical hormone replacement therapy guide separates a regulated body-identical prescription from a compounded mix.

If you are still working out which stage you are in, the stage checker uses your age and your last period. Take the menopause symptom checklist for your GP to the appointment. Anxiety and low mood are covered in HRT, anxiety and low mood. Whether HRT changes body weight is covered in Does HRT cause weight gain?.