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Incidence of circulating tumor cells (CTCs) in peripheral blood of breast cancer patients at primary diagnosis-A potential tool for risk stratification.

20053 Background: In metastatic breast cancer, CTCs have been proven an independent predictor for progression-free and overall survival (Cristofanilli, NEJM 2004). Therefore, we evaluated the role of CTCs in peripheral blood of breast cancer patients at primary diagnosis and during adjuvant systemic treatment within the Success-Trial (n = 3,658 pts). First results of the incidence of CTCs prior to chemotherapy will be presented here.


METHODS
The CellSearchSystem (Veridex) was used for isolation and enumeration of CTCs from 23 ml of peripheral blood. Briefly, after immunomagnetic enrichment with an anti-Epcam-antibody, cells were labelled with anti-cytokeratin (8,18,19) and anti-CD45 antibodies to distinguish epithelial cells and leukocytes. Patients had been accrued between September and December 2005.


RESULTS
We analyzed 124 breast cancer patients at the time of primary diagnosis. The majority of patients presented with small tumors (41% T1, 55% T2, 4% T3), and 32% were node-negative (45% N1, 14% N2, 9% N3). While a positive hormone receptor status was observed in 74% of patients and 31% were her2/neu positive, most tumors showed an intermediate or unfavourable grading (2% G1, 98% G2-3). In this patient group, 32% of patients (n = 40) presented with ≥1CTC in peripheral blood. In patients with the detection of CTCs, the mean number of cells was 5 (range 1-38). In 11 healthy individuals we found 1 CTC in one blood sample. The presence of CTCs did not correlated with tumor size (p = .39), presence of lymph node metastases (p = .25), histopathological grading (p = .33), hormone receptor status (p = .56) or her2/neu status of the primary tumor (p = .14).


CONCLUSIONS
The isolation of CTCs from peripheral blood of primary breast cancer patients is feasible and might prove as an easy applicable and convenient technique to give further insight into the spread of the disease. The Success-Trial will investigate, whether CTCs can be used for risk stratification to more tailored treatment approaches and for the monitoring of treatment efficacy in individual patients. [Table: see text].