Research shows a blood test developed by MFT could benefit thousands of women eligible for preventative breast cancer drug

A highly sensitive hormone blood test, developed by scientists at Manchester University NHS Foundation Trust (MFT) can determine the effectiveness of the drug anastrozole, the recommended preventative treatment for post-menopausal women at high risk of developing breast cancer.

This new research, published in the Lancet Oncology by Professors Gareth Evans, Anthony Howell and Brian Keevil at MFT, led by Jack Cuzick, and John Snow, Professors of Epidemiology at Queen Mary University of London,  found that up to 25 per cent of post-menopausal women at high risk, will not benefit from taking the drug.

Routinely testing hormone levels will enable clinicians to provide a personalised treatment plan for those at high risk of developing breast cancer. This will not only provide reassurance where the treatment is known to have a positive effect, but it will also spare thousands of women unnecessary side effects of taking the drug.

In post-menopausal women, an increased risk of breast cancer is associated with high serum concentrations of oestradiol (a type of oestrogen produced predominantly by the ovaries before the menopause), but little was known about how these hormones affect the response to anastrozole in breast cancer prevention, prior to this research.

Professor D Gareth Evans, Consultant in Medical Genetics and Cancer Epidemiology at MFT, said: “These results indicate the importance of incorporating serum oestrogen levels into risk models, so women can be reassured despite other risk factors if their levels are low, and likewise, higher levels may make more women eligible for anastrozole.”

Anastrozole lowers oestrogen levels in post-menopausal women – which otherwise can fuel the growth of breast cancer cells. The aromatase inhibitor, (type of hormone therapy drug), is taken as a 1mg tablet, once a day over a five-year period. It can only be taken by women post-menopause because the drug cannot suppress oestrogen in women whose ovaries are still working.

The drug has been recommended by the National Institute for Health and Care Excellence (NICE) since 2017 as a preventive treatment and it has recently been licensed on the NHS (November 2023) by the Medicines and Healthcare products Regulatory Agency (MHRA) for this purpose.

This is a result of previous findings from the IBIS-II prevention trial, supported by researchers at MFT, which found anastrozole reduces the incidence of breast cancer in post-menopausal women at increased risk, by 49 per cent.

Professor Anthony Howell, Emeritus Consultant in Medical Oncology at MFT said: “As a result of our previous research, anastrozole is now the drug of choice for preventing breast cancer in high-risk women after the menopause.

“Through this latest study we aimed to better understand who did or did not benefit from the drug, to identify if this treatment could be targeted more effectively for patient benefit.

“Our results indicate that we need to routinely assess hormone levels before prescribing anastrozole to ensure women are receiving the most beneficial preventative medication to them.”

The study found that for women with low levels of oestradiol, anastrozole would provide little or no reduction in the risk of breast cancer. These women could therefore avoid five years of possible side effects of the drug, which commonly include hot flushes, aches and low mood.

Professor Brian Keevil, Clinical Lead for Biochemistry, Wythenshawe Hospital, said: “To ensure we could accurately measure oestradiol levels in post-menopausal women at high risk of breast cancer, we developed a highly sensitive blood test at MFT, specifically for this purpose.

“This method of testing is the first of its kind and we are the only biochemistry laboratory in the country capable of measuring the very low concentrations of oestradiol often found in breast cancer patients – which is an indicator of the effectiveness of anastrozole for women.

“Many laboratories across the country have the ability to adopt this inexpensive method of testing, which will have real benefits to patients.”

The study, analysed data from the IBIS-II prevention trial, conducted between 2003 to 2012. Professor Cuzick from Queen Mary and researchers at MFT are now discussing the next steps for the findings of this research.

Jack Cuzick, Professor of Epidemiology at Queen Mary University of London said: “These results are very exciting and can refine how we choose preventive medication for post-menopausal women at high risk of breast cancer. Further research is needed to understand how this hormone level test could be integrated into routine testing and I look forward to working with the Manchester team to develop a plan to take this forward.”