title: Dynamics of circulating endothelial cells and endothelial progenitor cells in breast cancer patients receiving cytotoxic chemotherapy.
abstract: BACKGROUND
  The abundance of circulating endothelial cells (CECs) and circulating endothelial progenitor cells (CEPs), which serve as surrogate markers for angiogenesis, may be affected by chemotherapy. We studied their dynamic change during consecutive cycles of chemotherapy.
  
  
  METHODS
  We collected blood samples from 15 breast cancer patients, who received a total of 56 courses of systemic chemotherapy, and measured the CECs, viable CECs (V-CECs), and CEPs by six-color flow cytometry within the seven days prior to chemotherapy, twice a week during the first and second cycles of chemotherapy, and then once a week during the subsequent cycles.
  
  
  RESULTS
  The CEC, V-CEC, and CEP levels all significantly decreased from day 1 of treatment to the first week of chemotherapy. After one week of chemotherapy, the CEC and V-CEC levels returned to a level similar to day 1. The CEP level remained significantly reduced after the first week of chemotherapy, but gradually rebounded until the next course of chemotherapy. After six cycles of chemotherapy, the total number of CEC and V-CEC cells trended toward a decrease and the CEP cells toward an increase. Clinical factors, including the existence of a tumor, chemotherapy regimens, and the use of granulocyte colony stimulating factor, did not significantly affect these results.
  
  
  CONCLUSIONS
  The CEC and CEP counts change dynamically during each course of chemotherapy and after the chemotherapy cycles, providing background data for any future study planning to use CECs and CEPs as surrogate markers of angiogenesis in antiangiogenesis treatments combined with chemotherapy.
authors.affiliation: Department of Oncology, Chi-Mei Hospital, Tainan, Taiwan.
authors.forename: Yu-Hsuan
authors.initials: YH
authors.lastname: Kuo
authors.forename: Ching-Hung
authors.initials: CH
authors.lastname: Lin
authors.forename: Wen-Yi
authors.initials: WY
authors.lastname: Shau
authors.forename: Te-Jung
authors.initials: TJ
authors.lastname: Chen
authors.forename: Shih-Hung
authors.initials: SH
authors.lastname: Yang
authors.forename: Shu-Min
authors.initials: SM
authors.lastname: Huang
authors.forename: Chun
authors.initials: C
authors.lastname: Hsu
authors.forename: Yen-Shen
authors.initials: YS
authors.lastname: Lu
authors.forename: Ann-Lii
authors.initials: AL
authors.lastname: Cheng
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D015415:Biomarkers / Q000032:analysis; D001943:Breast Neoplasms / Q000097:blood / Q000188:drug therapy* / Q000473:pathology; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009360:Neoplastic Cells, Circulating / Q000187:drug effects* / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000473:pathology; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects*
chemical_list: D000970:Antineoplastic Agents; D015415:Biomarkers