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Tumor Cells Prognostic of Survival in Breast Cancer

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The presence of a large number of tumor cells circulating in the blood is associated with a significantly poorer overall survival among patients with metastatic breast cancer who are treated with chemotherapy. These results were recently published in the Journal of Clinical Oncology.

Research has recently been focused on the potential indicators of overall survival and other outcomes among patients with increased numbers of circulating tumor cells (CTCs) found in their circulating in their blood.

To further evaluate this possible association, researchers recently evaluated women with metastatic (advanced) breast cancer with different levels of CTCs. Specifically, the researchers were evaluating whether changing chemotherapy regimens among women whose CTCs were consistently high would improve survival.

The current trial included nearly 600 patients with metastatic breast cancer. All patients had their CTC levels measured prior to, and during therapy.

Among these patients, those who had highly elevated levels of CTCs prior to chemotherapy were divided into two groups: one group whose CTC levels remained high after 21 days of therapy, and one group whose CTC levels decreased after 21 days of therapy.

The group whose CTC levels remained high during the first 21 days of chemotherapy were switched to a different chemotherapy regimen. The group whose CTC levels decreased during the first 21 days of chemotherapy remained on that regimen until their cancer later progressed.

Overall survival of the different groups was the following:

Patients with low CTC levels prior to therapy had a median overall survival of 35 months.
Patients with CTC levels that decreased after 21 days of initial chemotherapy had a median overall survival of 23 months.
Patients with CTC levels that did not decrease after 21 days of initial chemotherapy had a median overall survival of 13 months.
The researchers concluded that CTC levels prior to therapy has significant prognostic value in terms of overall survival among patients with metastatic breast cancer. In addition, patients with CTC levels that decreased after 21 days of initial chemotherapy had improved survival compared to those with CTC levels that did not decrease after 21 days, despite the fact that they were treated with a different subsequent chemotherapy regimen.

Further research and clinical trials is warranted for patients with high levels of CTCs.

Reference: Smerage J, Barlow W, Hortobagvi G, et al. Circulating tumor cells and response to chemotherapy in metastatic breast cancer: SWOG SO500. Journal of Clinical Oncology. 2014:3483-3498; DOI:10.1200/JCO.2014.56.2561.