Breast cancer risk of HRT ‘far higher than feared’

WOMEN taking the most common form of HRT are at far higher risk of developing breast cancer than previously feared, a study has found.

Previous research has shown that long-term use of hormone-replacement therapy tablets is linked with increased risks of breast cancer, mostly due to the use of progestogens.

A study published by Oxford University last year found that oestrogen and progestogen raised the risk by 31 per cent. But newer figures, based on 20 years of data, show the risk increased by nearly 80 per cent.

Around one million women take HRT treatments in the UK, which include tablets containing oestrogen only, or a combination of oestrogen and progestogen, as well as patches, gels and creams.

Most women take a combined form of progestogen alongside oestrogen. This latest study, published in the British Medical Journal, compared

HRT prescriptions for around 98,000 women aged 50 to 79 who were diagnosed with breast cancer between 1998 and 2018, with those of around 457,000 women of the same age who did not develop breast cancer.

Researchers analysed risks by HRT type, by recent and past use, and by short-term and long-term use. Other factors, such as smoking, alcohol consumption and pre-existing conditions were taken into account.

Overall, a third of women with a breast cancer diagnosis and just under a third of women without had used HRT.

For long-term users, compared with those who had never used the treatment, there was a 15 per cent associated increased risk of developing breast cancer for oestrogen-only therapy. This rose to 79 per cent for combined therapy, compared with those who had never used HRT.

Per 10,000 women aged 60 to 69 who are taking combined therapy, there would be, on average, 15 extra cases of breast cancer in those who have been taking it for less than five years, and 26 extra cases for those who have been taking it for longer, study author Dr Yana Vinogradova, of the University of Nottingham, said. Being an observational study, a cause between HRT and breast cancer cannot be established, she said.

But she added: “This study confirms that exposure to most HRT drugs is associated with an increased risk of breast cancer. The levels of risks vary between types of HRT, with higher risks for combined hormone treatments and for longer duration of use.”