Circulating Tumor Cells, Disease Progression, and Survival in Metastatic Breast Cancer

We tested the hypothesis that the level of circulating tumor cells can predict survival in metastatic breast cancer.

In a prospective, multicenter study, we tested 177 patients with measurable metastatic breast cancer for levels of circulating tumor cells both before the patients were to start a new line of treatment and at the first follow-up visit. The progression of the disease or the response to treatment was determined with the use of standard imaging studies at the participating centers.