The researchers, from the Translational Genomics Research Institute (TGen) and the Cambridge Institute, have created a new technique called TARDIS, which analyses the levels of tumour DNA circulating in the blood, and has the potential to inform treatment decisions.

The new, highly sensitive blood test could be used to monitor how breast cancers respond to treatment given before surgery, called neoadjuvant treatment. Around 30% of breast cancers respond extremely well to neoadjuvant treatment, meaning some women may not require surgery. However, there is currently no way to identify who these women are before surgery and it’s hoped that this test could help doctors to personalise treatment plans for each patient. 

In this study, TARDIS detected tumour DNA in the blood of all of the 33 women before treatment. 22 of these women received treatment before surgery, and blood samples were taken before, during and after their treatment. 

After treatment, tumour DNA in the blood was detected in 17 out of the 22 women, and 13 women still had leftover disease after their pre-surgery treatment. In general, TARDIS was successful at identifying cases where breast cancer was no longer detectable after treatment and cases where some cancer cells were still there following treatment. 

On average, tumour DNA was 5.7 times higher in patients who still had leftover disease following neoadjuvant treatment compared to those who had no evidence of the disease. These results suggest that in the future this test could help to identify those who require surgery and further treatment and those who may not need it.

Dr Kotryna Temcinaite, Research Communications Manager at Breast Cancer Care and Breast Cancer Now, said:

“It’s really promising that this blood test may be able to monitor how a patient’s cancer is responding to initial treatment, and could help identify women who could be spared surgery.

“We urgently need to find new therapies to stop more women dying from breast cancer, but we also need to find ways to ensure we are giving patients the most appropriate treatment for them. The ability to assess who could be safely spared more extensive breast cancer treatment using a highly sensitive test like this could be a major step towards improving patients’ wellbeing and quality of life

“We now look forward to seeing how this test works in a larger study to help us understand its full potential and how effective it might be in different types of breast cancer. Liquid biopsies are showing great potential to help guide treatment decisions, monitor treatment response and detect the return of breast cancer. We await further research to understand how tests like this could help improve the lives of breast cancer patients.

“In the meantime, any women concerned about their breast cancer or treatment can call our free Helpline on 0808 800 6000 to speak to one of our expert nurses.”

This study was funded by Cancer Research UK. 

Find out more about what our scientists have been doing with liquid biopsies here.