An Analysis of the SWOG S0500 Study

Robert McCormack, PhD, head, Technology Innovation, Janssen Diagnostics, LLC, discusses the SWOG S0500 study, which evaluated different treatments in patients with metastatic breast cancer who had elevated circulating tumor cell (CTC) levels.

Clinical Pearls:

• The trial had three arms and enrolled patients with metastatic breast cancer that were about to start first-line chemotherapy treatment
• The patients were given a screening CTC test with CellSearch prior to the start of their treatment
• Patients with less than 5 CTCs were put in arm A while patients with more than 5 CTCs received their chemotherapy treatment for three weeks before receiving another CTC test
• The patients whose CTC levels dropped after three weeks were placed in arm B while the patients whose CTC levels did not drop after three weeks were placed in arm C
• Patients in arm C were either randomized to continue their current treatment or were switched to the next line of chemotherapy
• Results showed that after three weeks of therapy, a survival benefit can be determined based on CTC levels