Understanding the risks of HRT 

When deciding whether to have hormone replacement therapy (HRT), it is important to understand the risks and put them into perspective.

Many medical studies on HRT have been published over the past 10 years that have received a great deal of negative publicity. As a result, many women have been reluctant to use HRT.

However, it could be argued that the data within the studies was misleading. For example, if you read an article that says using combined HRT for five years increases your risk of developing breast cancer by 60%, you may be alarmed.

While this is statistically true, the average risk of developing breast cancer without other contributory risk factors (your annual baseline risk) is very small, at just 1%. The risk increases the longer you take HRT, but your risk level can gradually return to normal if you stop taking HRT.

Breast cancer

Cancer Research UK summarises the breast cancer risk associated with HRT as follows:

  • Research has shown that taking HRT does increase breast cancer risk.
  • Combined HRT increases breast cancer risk more than oestrogen-only HRT.
  • Women taking combined HRT have double the breast cancer risk of women who do not take HRT.
  • The longer you take HRT, the more your breast cancer risk increases.


  • Your risk appears to return to normal within five years of stopping taking HRT.

Read more about HRT and breast cancer risk on the Cancer Research UK website.

Due to the associated risk of breast cancer, it is important to attend all your breast-screening appointments if you are taking HRT.

Ovarian cancer

Cancer Research UK summarises the ovarian cancer risk associated with HRT as follows:

  • Research has shown that taking HRT slightly increases the risk of developing ovarian cancer.
  • The longer HRT is taken, the more the risk increases.


  • When HRT is stopped, risk returns to normal over the course of a few years.

Read more about HRT and ovarian cancer risk on the Cancer Research UK website.

Womb cancer

If you take progestogen as directed, there is no increased risk of developing womb (uterus) cancer, which is sometimes referred to as endometrial cancer.

It is very important you take progestogen as directed, because only taking oestrogen will significantly increase your risk of developing womb cancer.

Combined HRT does not increase the risk of womb cancer.

Stroke and heart attacks

The latest analysis from Women's Health Concern regarding the risk of heart disease and stroke for women taking HRT states that:

  • the risk of stroke is increased in women who smoke and are overweight
  • women starting HRT and aged below 60 are not at an increased risk of stroke
  • HRT is not recommended for women with a history of stroke or deep vein thrombosis (DVT)

Speak to your GP if you are taking HRT and are worried about the risk of stroke or heart disease.

Page last reviewed: 18/08/2014

Next review due: 18/08/2016