Name of the Trial
Phase III Randomized Study of Treatment Decision Making Based on Levels of Circulating Tumor Cells in Women with Metastatic Breast Cancer Undergoing Chemotherapy (SWOG-S0500). See the protocol summary at http://www.cancer.gov/clinicaltrials/SWOG-S0500

Principal Investigators
Dr. Jeffrey Smerage and Dr. Daniel Hayes, Southwest Oncology Group; Dr. Eric Winer, Cancer and Leukemia Group B

Why This Trial Is Important
In treating women with metastatic breast cancer, doctors often start with the least toxic chemotherapy regimen in order to minimize side effects and then pursue more aggressive combinations if the cancer continues to grow (progress). However, the clinical signs of progression may take months to appear, and, during this time, patients may be undergoing treatment that is not helping them.

Recent studies have suggested that the level of circulating tumor cells (CTCs) in a patient's blood might be useful as an indicator of prognosis. Now doctors want to see if measuring CTC levels before and during chemotherapy can be used to guide treatment decisions - specifically, whether to switch chemotherapy regimens before clinical signs of tumor progression emerge.

In this trial, patients will have a blood test to measure the CTC level. Women with fewer than 5 CTCs per 7.5 ml of blood will start standard-of-care therapy, including chemotherapy and any targeted agents that may be appropriate. Women with elevated CTCs (5 or more cells per 7.5 ml of blood) will also begin standard therapy and be tested again after their first round of treatment (about 3 weeks). Those who still have elevated CTCs will be randomly assigned to either stay on their current chemotherapy regimen or switch to a different regimen; those with fewer than 5 CTCs will remain on their current treatment.

"We know patients with elevated CTCs face significantly shorter time-to-progression and survival," said Dr. Smerage. "By testing patients at baseline and then again after the first round of chemotherapy, we hope to tell when the patient isn't benefiting and whether switching drugs helps spare them unnecessary side effects and perhaps gets them onto a more effective regimen."

For More Information
See the lists of entry criteria and trial contact information at http://www.cancer.gov/clinicaltrials/SWOG-S0500 or call the NCI's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237). The toll-free call is confidential.