title: Improving the yield of circulating tumour cells facilitates molecular characterisation and recognition of discordant HER2 amplification in breast cancer.
abstract: BACKGROUND
  Circulating tumour cells (CTCs) offer a non-invasive approach to obtain and characterise metastatic tumour cells, but their usefulness has been limited by low CTC yields from conventional isolation methods.
  
  
  METHODS
  To improve CTC yields and facilitate their molecular characterisation we compared the Food and Drug Administration-approved CellSearch Epithelial Kit (CEK) to a simplified CTC capture method, CellSearch Profile Kit (CPK), on paired blood samples from patients with metastatic breast (n=75) and lung (n=71) cancer. Molecular markers including Human Epidermal growth factor Receptor 2 (HER2) were evaluated on CTCs by fluorescence in situ hybridisation (FISH) and compared to patients' primary and metastatic cancer.
  
  
  RESULTS
  The median cell count from patients with breast cancer using the CPK was 117 vs 4 for CEK (P<0.0001). Lung cancer samples were similar; CPK: 145 cells vs CEK:4 cells (P<0.0001). Recovered CTCs were relatively pure (60-70%) and were evaluable by FISH and immunofluorescence. A total of 10 of 30 (33%) breast cancer patients with HER2-negative primary and metastatic tissue had HER2-amplified CTCs.
  
  
  CONCLUSIONS
  The CPK method provides a high yield of relatively pure CTCs, facilitating their molecular characterisation. Circulating tumour cells obtained using CPK technology demonstrate that significant discordance exists between HER2 amplification of a patient's CTCs and that of the primary and metastatic tumour.
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Flores
authors.forename: D W
authors.initials: DW
authors.lastname: Kindelberger
authors.forename: A H
authors.initials: AH
authors.lastname: Ligon
authors.forename: M
authors.initials: M
authors.lastname: Capelletti
authors.forename: M
authors.initials: M
authors.lastname: Fiorentino
authors.forename: M
authors.initials: M
authors.lastname: Loda
authors.forename: E S
authors.initials: ES
authors.lastname: Cibas
authors.forename: P A
authors.initials: PA
authors.lastname: Jänne
authors.forename: I E
authors.initials: IE
authors.lastname: Krop
mesh_terms: D001943:Breast Neoplasms / Q000097:blood / Q000235:genetics*; D005260:Female; D005455:Fluorescent Antibody Technique; D005784:Gene Amplification; D018734:Genes, erbB-2 / Q000235:genetics*; D006801:Humans; D018189:Immunomagnetic Separation / Q000379:methods*; D017404:In Situ Hybridization, Fluorescence; D009360:Neoplastic Cells, Circulating
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