Julie R. Gralow, MD, director, Breast Medical Oncology, Seattle Cancer Care Alliance, clinical research division, member, Fred Hutchinson Cancer Care Center, professor, Medical Oncology Division, University of Washington School of Medicine, discusses the SWOG S0500 trial, which evaluated different treatments in patients with metastatic breast cancer who had elevated circulating tumor cell (CTC) levels.
Gralow says the CTC levels of newly diagnosed metastatic breast cancer patients were measured before receiving chemotherapy. If the levels were low, the patients were put in an observation arm. If the levels were high, the patients received one cycle of chemotherapy before having their CTC levels tested again.
Gralow says if the patient’s CTC levels were low, they continued with chemotherapy treatment but if the patient’s CTC levels remained the same or were elevated, those patients were randomized to either keep going on the same therapy or to change them to a different type of chemotherapy. Additionally, Gralow notes, bevacizumab and trastuzumab were allowed in the trial.
Gralow says the results showed that the patients who had low CTC levels to begin with did the best. The patients who had elevated levels prior to chemotherapy but had lower levels after chemotherapy did moderately well while the patients whose levels remained elevated throughout the trial did poorly no matter what.
The conclusion, Gralow says, is that it is a poor prognostic sign to have high CTC levels. The trial also showed that switching to a different chemotherapy sooner does not improve outcomes. For these patients, a clinical trial to look at new targeted therapies should be considered, since chemotherapy is not effective in this population of patients.
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