Tumor DNA circulating in patients' blood after pre-surgery treatments predicts whether breast cancer will return

Fragments of tumor DNA circulating in the bloodstream of patients with breast cancer can predict whether they are likely to relapse, especially when samples are taken after the patients have received treatments prior to surgery. The study, to be presented at the 15th European Breast Cancer Conference (EBCC15) in Barcelona on Friday, included the largest number of events reported so far for circulating tumor DNA (ctDNA) in individual patients. Events could include the tumor starting to grow again, cancer cells spreading to other parts of the body (metastasizing), death or a new tumor in the same or the second breast.