HRT increases your risk while you’re taking it – but within a year or two after you’ve stopped, this increased risk largely disappears

  • The longer you use HRT, the greater your risk
  • Your risk will drop back to normal within a year or two of stopping
  • Breast cancer risk is greater with combined HRT than with oestrogen-only HRT

How much does combined HRT increase my risk of breast cancer?

Studies have shown that the use of HRT to treat menopausal symptoms increases your risk of breast cancer during the years you take it. The longer you use HRT, the greater your risk.

But once you stop taking HRT, this risk will begin to fall. Within a year or two, it will be about the same as if you had never taken it. The graphs below show how much using combined HRT (which contains both oestrogen and progestogen) can increase your risk of breast cancer. These examples show how many women out of 1,000 will develop breast cancer, depending on whether or not they use HRT, and for how long.

The graphs below show how much using combined HRT (which contains both oestrogen and progestogen) can increase your risk of breast cancer. These examples show how many women out of 1,000 will develop breast cancer, depending on whether or not they use HRT, and for how long.

Using combined HRT for less than five years between the ages of 50 and 54

  • In every 1,000 women who don’t use HRT, about 12 will develop breast cancer between the ages of 50 and 54. Find out how age affects breast cancer risk
  • In 1,000 women using combined HRT for fewer than five years, about 19 in every 1000 will develop breast cancer between the ages of 50 and 54
  • So, using combined HRT for fewer than five years leads to about seven extra women out of 1,000 to develop breast cancer between the ages of 50 and 54

Using combined HRT for five to nine years between the ages of 50 and 59

  • In 1,000 women who don’t use HRT, about 21 will develop breast cancer between the ages of 50 and 59. Find out how age affects breast cancer risk
  • In 1,000 women using combined HRT for 5 to 9 years, about 80 will develop breast cancer between the ages of 50 and 59
  • So using combined HRT for this period of time leads to about 59 more women to develop breast cancer between the ages of 50 and 59

So, the longer you use combined HRT, the greater your risk. Although there’s no limit on how long you can use HRT, most women stop taking it once their symptoms pass – this is normally after a few years. If you decide to take HRT, your doctor will be able to advise you on how long and what dose is appropriate for you depending on your symptoms.

It’s important to remember that within a year or two of stopping HRT, this risk will drop.

If you are worried about your HRT and breast cancer, talk to your doctor. They will be able to give you more information and advice.

What about other types of HRT?

The risk linked to oestrogen-only HRT (HRT containing only oestrogen) is less than with combined HRT. The most recent research suggests that oestrogen-only HRT might have no risk when only used for a few years, but probably increases your risk when used for 10 to 14 years.

Oestrogen-only HRT increases the risk of womb cancer, so is generally only offered to women who have had their womb removed (hysterectomy). Tibolone (Livial) is another type of HRT that contains a steroid that acts like oestrogen and progesterone.

Tibolone users also have an increased risk of breast cancer, but probably less so than combined HRT users.

Find out more about HRT from NHS Choices.

Talk to your doctor when deciding to start or stop taking HRT, or if you are worried about HRT and breast cancer. They can give you more information and advice.

It is not clear whether any type of HRT is safe if you’ve had breast cancer. Some studies have shown that tibolone, in particular, may increase the risk of breast cancer coming back. You’re not normally prescribed HRT if you’ve had breast cancer, other than in exceptional circumstances. You may be offered alternative drugs, and there are other natural remedies that may help. Talk to your oncologist before beginning any treatment or taking any supplements to relieve menopausal symptoms to check whether they are safe and suitable for you.

HRT helps relieve symptoms by increasing oestrogen levels. We don’t know for sure why HRT increases the risk of breast cancer, but research indicates that the higher levels of hormones causes some breast cancers to grow.

If you have inherited the faulty breast cancer gene BRCA1 or 2, we recommend you speak to your family history or genetics specialist if you wish to use HRT. Our family history guide provides more information about HRT, family history and breast cancer.

HRT increases your breast cancer risk during the years you take it, but it also helps to relieve many women’s menopausal symptoms. It can also reduce a woman’s risk of developing osteoporosis (weak bones) in the short term and improve muscle strength. It has some side effects such as headaches, feeling sick and breast tenderness. These usually happen in the first few months. Taking HRT also slightly increases the risk of having a blood clot or a stroke, and might slightly increase the risk of ovarian cancer.

How is our data calculated?

We base our calculations on evidence that we judge to be reliable and of most relevance to the UK population. We’d like to thank the Statistical Information Team at Cancer Research UK for providing us with baseline data (June 2017).

Some of the data we used came from findings from Breast Cancer Now’s Generations Study. Find out more about our landmark study into understanding the causes of breast cancer.

Note: Some figures have been rounded up for clarity.

References

Jones, M. E. et al. Menopausal hormone therapy and breast cancer: what is the true size of the increased risk? Br. J. Cancer 115, 607–615 (2016)

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Information last reviewed: November 2017

Next review due: November 2020

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