Circulating tumor cells or CTCs in bone marrow of early breast cancer patients predict a higher risk of relapse as well as poorer survival. To confirm, bone marrow biopsy, an invasive and painful procedure, is generally used to identify these circulating tumor cells. But according to a new study published May 15, 2014 in the Journal of the National Cancer Institute, it may be possible to identify these tumor cells in a routine blood sample and use them as prognostic markers.
To assess the prognostic value of circulating tumor cells (CTCs) in patients with early breast cancer, Brigitte Rack, M.D., of the Department of Gynecology and Obstetrics, Klinikum Innenstadt, Ludwig-Maximilians-Universitaet Muenchen, in Munich, Germany, and her colleagues analyzed CTCs in peripheral blood from patients from the SUCCESS trial, an open-label, multicenter, 2×2 factorial design, randomized controlled, Phase III study comparing the time to recurrence after randomisation in patients with early primary breast cancer.  The researchers took samples from 2026 patients after primary surgery and before systemic treatment and in 1492 patients after chemotherapy.
… the data offers support for the clinical potential of CTCs to assess the individual risk of patients at the time of primary diagnosis …and may be used for treatment tailoring in the absence of other strong quantitative markers…
CTC before and after treatment
The patients were classified into four groups: positive for CTCs both before and after treatment, negative for CTCs both before and after, positive for CTCs before but negative after, and negative CTCs before but positive after treatment. Those with positive CTCs both before and after treatment had the worst disease-free survival compared to the other three groups. Overall, the probability of being disease-free at 36 months after surgery was lower for patients with CTCs than for patients without, and of those patients who died during follow-up, 40.9% had CTCs in their blood compared to 20.8% of patients who survived. In addition, the greater the CTC count, the worse the prognosis. Patients with 5 or more CTCs in 30ml of blood were at higher risk of recurrent disease.
Guiding therapeutic choices
The authors noted that their data offers support for the clinical potential of CTCs to assess the individual risk of patients at the time of primary diagnosis and may be used for treatment tailoring in the absence of other strong quantitative markers. However, they also note that although they used only two markers to detect CTCs, the identification of other markers could make CTCs even more useful in predicting metastases and guiding therapeutic choices.
Arnold M. Schwartz, M.D., Ph.D., of the Department of Pathology and Surgery and Norris Nolan, M.D., of the Department of Pathology at The George Washington University, Washington, DC, in an accompanying editorial, writes that the work of Rack et al. is notable because of the large cohort, the focus on early breast cancer, and sampling both before and after treatment and that “The identification of CTCs represents an additional biomarker that provides insight into clinical behavior.”
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