Women with metastatic breast cancer who have no tumor cells circulating in their blood after the first round of treatment live longer than those who do, French researchers report.Circulating tumor cells, or CTCs, are cells that break off from a tumor and escape into the bloodstream. These cells can travel to other organs and establish new tumors.

Several studies have shown that higher levels of CTCs are associated with an increased risk for recurrence and death in metastatic breast cancer patients.But the new study is the largest to look at the topic, and the CTCs predicted prognosis even after taking other markers of survival into account, says Jean-Yves Pierga, MD, PhD, professor of the medical oncology department at Institut Curie and Universite Paris Descartes, France.

via Wandering Tumor Cells Predict Poor Outcome.