Photo: AP Test can also detect mutations in cancer genes

BREAST cancer patients could be helped by a new blood test that can tell when they are on the wrong treatment.

It identifies whether tumours have become resistant to the drugs the women are on, prompting doctors to try something different.

The test can also detect mutations in cancer genes – again suggesting an alternative treatment might be better.

Researchers hope this will benefit the 3,500 British women a year whose breast cancers have spread to surrounding tissue or organs.

Known as a liquid biopsy, the test has been developed by Imperial College London, the University of Leicester and Cancer Research UK and Breast Cancer Now.

Early trials have shown it could benefit a fifth of women with advanced breast cancer – potentially extending their lives and avoiding unnecessary treatment. The research team will now carry out much larger trials to check the test is accurate and safe.

This extensive process means it is unlikely to be available in hospitals for at least five years.

But researchers are extremely excited about liquid biopsy and believe they have the potential to halve cancer deaths by guiding doctors to the best course of treatment.

As with any other blood test, patients provide a sample of blood which is then analysed in a laboratory. A scanning machine looks for tiny fragments of tumour DNA that are deposited in the blood stream as the cancer grows and develops.

The fragments provide crucial information about the specific type of cancer and whether it has mutated since it was first diagnosed. This tells doctors whether they need to switch treatments.

The test would be used for women with advanced breast cancer which is usually treated with a group of drugs called aromatase inhibitors. Often however the cancer becomes resistant to treatment, or mutates.

Researchers used the test on 42 patients and in nine cases it was able to identify that doctors needed to switch drug. Baroness Delyth Morgan of Breast Cancer Now said: ‘This is an important step forward in monitoring metastatic breast cancer that brings us closer to having a useful blood test in the clinic.

‘Liquid biopsies are not only less invasive, but could also give a fuller picture of the genetic changes happening in a patient’s tumour that might affect their response to treatment.’

There are around 55,000 new cases of breast cancer a year in the UK and 11,500 deaths.

Although the survival chances are good for women diagnosed with the disease early, they are much bleaker for those whose tumours have spread to other tissue and organs.

Justine Alford of Cancer Research UK said: ‘While survival for women with early breast cancer has greatly improved, the outlook for patients with advanced disease is still poor, something we urgently need to change.

‘This early research could help achieve this.The researchers may have developed a way to track breast cancer as it grows, allowing doctors to act swiftly and give treatments that are right for them as early as possible.

‘On top of that, such a tailored approach could spare patients receiving drugs, and the side effects that go with them, that aren’t likely to work.

‘If proven to be effective in further, larger studies, this research could help more women survive advanced breast cancer.’

The findings are published in the journal Clinical Chemistry.

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