Scientists have developed a simple blood test that can predict how well patients with breast cancer are likely to respond to specific treatments, potentially allowing doctors to tailor therapy far earlier than is currently possible.
The test analyses circulating tumour DNA (ctDNA) – tiny fragments of genetic material released into the bloodstream by cancer cells. In a study involving 167 patients with advanced breast cancer, researchers found that low levels of ctDNA before treatment, or after just four weeks of therapy, were strongly linked to better outcomes.
Patients with low or undetectable ctDNA were more likely to see their tumours shrink and experienced significantly longer periods before their cancer progressed. This was particularly striking in people with triple-negative breast cancer, an aggressive form of the disease with limited treatment options.
Researchers say the test could help doctors avoid giving patients drugs that are unlikely to work and instead switch earlier to alternative treatments or clinical trials. Trials are now under way to determine whether adapting treatment based on these early blood test results can improve long-term outcomes.
