Scientists develop blood test that can identify which breast cancer patients will likely relapse after surgery

Scientists have developed a blood test that can identify which breast cancer patients are likely to suffer a relapse after surgery – a breakthrough which has the potential to spare thousands of women from undergoing unnecessary chemotherapy and other treatments.

The blood test has only been tested in 55 women, but showed highly promising results and has been hailed as a potential “game-changer” by experts.

It works by uncovering small numbers of residual cancer cells that may have resisted therapy, by detecting cancer DNA in the bloodstream.

In early trials, women who tested positive for tumour DNA in the bloodstream were 12 times more likely to suffer a relapse, and the return of their cancer was detected on average eight months before any visible signs emerged.

The research, carried out by the Institute for Cancer Research (ICR) and the Royal Marsden NHS Foundation Trust, is now set for clinical trials next year. It could be several years before the test is available in hospitals, but if its effectiveness is confirmed, it could benefit thousands of women.

There are around 50,000 new cases of breast cancer in the UK every year.

Currently, the vast majority of women who have undergone surgery for breast cancer have to undergo further treatment, often with gruelling side effects, to lower their risk of a relapse. A test that can reveal, far in advance, whether women are at high risk of a relapse or not, could mean further treatment would be necessary for a much smaller number of women.

Professor Mitch Dowsett, head of the academic department of biochemistry, at the ICR and Royal Marsden, a senior author of the study, said that the test could change breast cancer patient’s treatment dramatically.

“A patient would come in, they would have their surgery, we would take their blood sample, and [if it was negative] we could say the DNA is undetectable in your blood, it would appear you have no minimal residual disease, we don’t think it’s worthwhile giving you any medical treatment at this time,” he said.

“We’ve been looking for this kind of thing for so long. If this continues to show the promise it currently is, then it’s got the chance of being a game-changer.”

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In the study, published in the journal Science Translational Medicine, researchers said the test also enabled better understanding of how cancers evolve over time, tracking the mutations that lead to a relapse.

This information could prove invaluable to doctors in choosing the best possible treatments for an individual patient, they said.

Professor Paul Workman, chief executive of the ICR, said: “We are moving into an era of personalised medicine for cancer patients. This test could help us stay a step ahead of cancer by monitoring the way it is changing and picking treatments that exploit the weakness of the particular tumour. It is really fantastic that we can get such a comprehensive insight about what is going on in the cancer all over the body, without the need for invasive biopsies.”

Katherine Woods, senior research communications manager at the charity Breast Cancer Now, said: “When breast cancer spreads to other parts of the body it becomes incurable, so we desperately need better ways to predict which cancers will spread and, in the future, stop this from happening altogether.

“This research not only has the potential to improve on current methods used to assess a patient’s prognosis soon after diagnosis, but it could also help to tailor the way women with early breast cancer are treated, presenting a new way to stay one step ahead of – and ultimately outsmart – the disease from the outset.”