Breast tumour DNA circulating in the bloodstream could be used to measure how well a woman’s cancer is responding to treatment, according to a new Cancer Research UK study published in the New England Journal of Medicine.

Professor Peter Johnson, Cancer Research UK’s chief clinician, said: “These results hold the promise of a system that could allow us to modify someone’s treatment as their cancer changes, and they suggest an exciting way to quickly get hold of the personal details of a cancer, to target it for the most effective therapy.

One of the things that will help our scientists design better cancer treatments is a way of measuring early on which ones are working and which are not. If we can find the molecular footprints of cancers during treatment and see how they change, we hope we will be able to track them down and remove them much more efficiently.”