Determining circulating endothelial cells using CellSearch system during preoperative systemic chemotherapy in breast cancer patients

Background: Circulating endothelial cells (CECs) have been studied as a biomarker for tumour progression and monitoring therapeutic effects. The CellSearch system is a semi-automated system that allows standardised analysis of CECs. This study assessed the clinical implications of CECs determined by the CellSearch system in breast cancer patients. Methods: Seventy-six consecutive breast cancer patients (53 operable and 23 metastatic or recurrent) were enrolled for the study. Thirty-five patients with operable breast cancer received preoperative chemotherapy with a regimen based on anthracycline and/or taxane. CECs are defined as CD146(+)CD105(+)CD45(-)DAPI(+) cells in the system. CD34 expression was examined using the additional channel in the system. Results: A majority (4539 of 5183 cells, 88%) of CECs from patients with operable breast cancer were CD34-positive. Triple-negative cancers showed higher baseline CEC and CD34(+)CEC counts than the other types (P = 0.0387 and 0.0377, respectively). Low baseline CEC and CD34(+)CEC counts, and a low CD34 positive rate were associated with pathological complete response (pCR) of preoperative chemotherapy in patients with primary breast cancer (P = 0.046, 0.027 and 0.01, respectively). In multivariate analyses, the CD34 positive rate was significant for pCR (P = 0.021). During preoperative chemotherapy; CEC and CD34(+)CEC counts before each cycle of chemotherapy increased with taxane-based regimens (P = 0.0018 and 0.0008, respectively) but not with anthracycline-based regimens. Conclusions: Baseline CEC, in particular CD34(+)CEC, counts and the CD34 positive rate might be useful for the prediction of treatment response of preoperative chemotherapy in patients with operable breast cancer. (C) 2011 Elsevier Ltd. All rights reserved.