Combined HRT could triple breast cancer risk, suggests major new study

HRT Pills Medicine

Hormone replacement therapy (HRT) could triple a woman’s risk of developing breast cancer, according to a major new prospective study published in the British Journal of Cancer.

HRT is prescribed to around one in ten women in their fifties who are dealing with uncomfortable menopausal symptoms caused by the natural decline of reproductive hormones, including mood changes, sleep disturbances, hot flushes, increased sweating, headaches and depression.

There are two main types of HRT – oestrogen-only HRT oestrogen and progestogen combined HRT, which may be administered in tablet form, via skin patches or applied via a skin cream or gel. The National Institute of Health and Care Excellence (NICE) issued guidance in 2015 to encourage more GPs to prescribe the treatment, after it found many menopausal women were struggling with their symptoms.

The research, carried out by The Institute of Cancer Research in London and supported by data supplied by charity Breast Cancer Now’s Generations Study, examined information relating to 100,000 women who were followed for a period of 40 years in order to investigate the causes of breast cancer. Around 39,000 of the women with a known age of menopause commencement were followed for a period of six years, with data relating to the use of HRT and general health and lifestyle collected.

Image Credit: Flickr Ed Uthman

Image Credit: Flickr Ed Uthman

Increased risk?

During the six-year period, 775 of the women developed breast cancer. The researchers found that the women who used combined HRT for on average 5.4 years were 2.7 times more likely to be diagnosed with breast cancer during the course of treatment than those who had never taken HRT. This risk was found to increase with longer treatment duration, with women who had taken combined HRT for 15 years or more being 3.3 times more likely to develop breast cancer, however, women who used the oestrogen-only form of HRT had no increased risk overall compared with those who had never used HRT.

However, any increased risk level appeared to return to normal within two years of ending HRT, a finding which supports that of previous studies.

A link between the use of HRT and an increased risk of breast cancer has previously been suggested following a study carried out in 2002, but one of the lead authors of this study says the latest findings indicate that the increased risk previously identified may have been underestimated.

Informed decisions

Study leader Professor Anthony Swerdlow, Professor of Epidemiology at the ICR says: “Our research shows that some previous studies are likely to have underestimated the risk of breast cancer with combined oestrogen-progestogen HRT. We found that current use of combined HRT increases the risk of breast cancer by up to three fold, depending on how long HRT has been used.

“Our findings provide further information to allow women to make informed decisions about the potential risks and benefits of HRT use.”

Woman Senior

Personal choice

Baroness Delyth Morgan, Chief Executive at Breast Cancer Now, says: “Whether to use HRT is an entirely personal choice, which is why it’s so important that women fully understand the risks and benefits and discuss them with their GP. We hope these findings will help anyone considering the treatment to make an even more informed decision.

“On balance, some women will feel HRT to be a necessity. But in order to minimise the risk of breast cancer during treatment, it is recommended that the lowest effective dose is used for the shortest possible time.

“The good news is that the increased risk of breast cancer begins to fall once you stop using HRT.”


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