(HealthDay News) — Circulating tumor cells (CTCs) are prognostic of poor survival in early breast cancer, according to a study published online May 15 in the Journal of the National Cancer Institute.
Brigitte Rack, MD, from the Ludwig-Maximilians-University Munich in Germany, and colleagues used the CellSearch System to analyze CTCs in 2,026 patients with early breast cancer before adjuvant chemotherapy and in 1,492 patients after chemotherapy. Nucleated cells expressing cytokeratin and lacking CD45 were classified as CTCs. The median follow-up was 35 months.
The researchers found that 21.5% of patients had CTCs before chemotherapy, including 19.6% of node-negative and 22.4% of node-positive patients (P<0.001). There was no correlation with tumor size, grading, or hormone receptor status.
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CTCs were detected in 22.1% of patients after chemotherapy. CTC presence correlated with poor disease-free survival (DFS), distant DFS, breast cancer-specific survival, and overall survival (OS).
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In multivariate analysis, CTCs were confirmed as independent prognostic markers for DFS (hazard ratio [HR], 2.11; P<0.0001) and OS (HR, 2.18; P=0.002). Patients with at least five CTCs per 30 mL blood had the worst prognosis for DFS and OS (HRs, 4.51 and 3.60, respectively). After chemotherapy, the presence of CTCs had a negative impact on DFS and OS (HRs, 1.12 [P=0.02] and 1.16 [P=0.06], respectively).
“These results suggest the independent prognostic relevance of CTCs both before and after adjuvant chemotherapy in a large prospective trial of patients with primary breast cancer,” the researchers wrote.
In an accompanying editorial, Arnold M. Schwartz, MD, PhD, and Norris Nolan, MD, both from George Washington University, wrote, “Given that hematogenous metastases occur through a complex biologic pathway of vascular invasion, circulation, identification of a favorable metastatic site, and clonal expansion, it appears intuitive that identification of the leukemic phase of CTCs in peripheral blood or the deposition phase of DTCs in vascular-rich environments may be prognostic for tumor recurrence and metastasis.”
Several authors disclosed financial ties to the pharmaceutical companies that funded the translational research part of the SUCCESS trial.
References
- Rack B, Schindlbeck C, Jückstock J, et al. Circulating Tumor Cells Predict Survival in Early Average-to-High Risk Breast Cancer Patients. J Natl Cancer Inst. 2014;doi:10.1093/jnci/dju066.
- Schwartz AM, Nolan N. Circulating Tumor Cells: What Goes Around, Comes Around. J Natl Cancer Inst. 2014;doi:10.1093/jnci/dju108.
