Blood test may one day predict breast cancer relapse

An experimental blood test may one day detect the return of early stage breast cancer months before it is revealed by CT or MRI scans, researchers report.

Initial treatment with surgery or chemotherapy can miss some cancer cells. The new test can detect DNA shed by tumors into the bloodstream before these stray cancer cells invade other organs, the British researchers said.

“Using a simple blood test, we might be able to better predict who is at risk of relapse,” said lead researcher Dr. Nicholas Turner, of the Breakthrough Breast Cancer Research Centre at the Institute of Cancer Research in London.

The test is still a long way from use in clinical practice, however. “This is the first study to show this, and much more study will be required before the test could enter the clinic,” he said.

One challenge in treating breast cancer is working out who is at risk of developing secondary cancer after treatment, Turner explained.

“If we can identify better who is at risk of relapse, we can direct treatments to prevent relapse specifically to them,” he said. “Women who still have tumor DNA detectable have a high risk of going on to relapse.”

For the study, published Aug. 26 in the journal Science Translational Medicine, Turner and colleagues studied 55 early stage breast cancer patients who had undergone chemotherapy followed by surgery. Blood samples were taken regularly for about two years after surgery to look for tumor-specific mutations in the patients’ blood.

Fifteen patients eventually saw their cancer return. Of these, 12 were identified by the blood test about eight months before conventional imaging detected the cancer, the researchers reported.