Scientists have developed a simple blood test that can predict how effectively a person with breast cancer will respond to treatment, potentially allowing doctors to tailor therapy much earlier and improve outcomes.
The test analyses circulating tumour DNA (ctDNA) – tiny fragments of genetic material released into the bloodstream by cancer cells. By measuring ctDNA levels before treatment begins and again after just one treatment cycle, researchers found they could reliably predict whether a patient’s cancer was likely to respond.
In a study involving 167 patients with advanced breast cancer, low levels of ctDNA before treatment were strongly linked to better responses and longer periods before the disease progressed. Patients whose ctDNA became undetectable after four weeks of treatment had significantly better outcomes than those whose ctDNA remained detectable.
The findings suggest the test could help clinicians quickly identify when a treatment is unlikely to work, enabling them to switch patients to alternative therapies or clinical trials sooner, rather than waiting months to see if a tumour shrinks.
Researchers say the approach could make cancer care faster, more personalised and more effective, and future trials will examine whether adapting treatment based on early ctDNA results improves survival and quality of life for patients.
