Blood test shows promise in predicting personalised treatment for breast cancer

Scientists have developed a DNA blood test that can help predict how well patients with breast cancer will respond to specific treatments, offering a potential boost to personalised cancer care.

Breast cancer remains one of the most common cancers worldwide, with the World Health Organization estimating 2.3 million diagnoses and about 670,000 deaths globally in 2022.

While treatment options have expanded, doctors still face challenges in determining which therapies will work best for individual patients.

The new study, conducted by researchers from The Institute of Cancer Research in London and published in the journal Clinical Cancer Research, focused on advanced breast cancer. The team analysed blood samples from 167 patients using a liquid biopsy to detect circulating tumour DNA, or ctDNA, which is released by cancer cells into the bloodstream.

Researchers measured ctDNA levels at the start of treatment and again after four weeks, then compared the results with clinical outcomes such as tumour response and the time taken for the cancer to progress. They found that lower levels of ctDNA at the start of treatment, and undetectable levels after four weeks, were linked to better responses and longer periods before disease progression.

In patients with triple-negative breast cancer, those with low ctDNA levels before treatment had a progression-free survival of 10.2 months, compared with 4.4 months for those with higher levels. Treatment response was also significantly higher in patients with low ctDNA.

Dr Iseult Browne, the study’s first author, said early prediction could help doctors avoid ineffective treatments and switch patients sooner to alternative therapies or clinical trials. Study lead Professor Nicholas Turner said the approach could eventually help make treatment decisions faster, more personalised and more effective, including for early-stage breast cancer.