Researchers have developed a blood test that can predict how well patients with breast cancer are likely to respond to specific treatments, potentially allowing doctors to tailor therapy much earlier.
The test analyses circulating tumour DNA (ctDNA) released into the bloodstream by cancer cells. In a study of 167 patients with advanced breast cancer, scientists found that low or undetectable levels of ctDNA before treatment – or after just four weeks of therapy – were strongly linked to better outcomes.
Patients with low ctDNA levels were more likely to see their tumours shrink and experienced significantly longer periods before their cancer progressed. The link was especially strong in patients with aggressive triple-negative breast cancer, who currently have fewer targeted treatment options.
Researchers say the test could help clinicians quickly identify when a treatment is unlikely to work, enabling patients to switch earlier to alternative drugs or clinical trials. While the study focused on advanced cancer, experts believe the approach could also be useful for early-stage disease.
Further trials are under way to determine whether adjusting treatment based on these early blood test results can improve long-term survival and quality of life.
