title: Most early disseminated cancer cells detected in bone marrow of breast cancer patients have a putative breast cancer stem cell phenotype.
abstract: OBJECTIVE
  The presence of disseminated tumor cells (DTC) in the bone marrow of breast cancer patients is an acknowledged independent prognostic factor. The biological metastatic potential of these cells has not yet been shown. The presence of putative breast cancer stem cells is shown both in primary tumors and distant metastases. These cells with a CD44(+)CD24(-/low) phenotype represent a minor population in primary breast cancer and are associated with self-renewal and tumorigenic potential. Recognizing the potential effect of prevalence of putative stem cells among DTC, we evaluated the bone marrow DTC.
  
  
  METHODS
  We employed the double/triple-staining immunohistochemistry protocol and modified the established bone marrow cytokeratin (CK) staining protocol by adding steps for additional antigens, CD44 and/or CD24. We evaluated 50 bone marrow specimens, previously categorized as CK(+) from early breast cancer patients. CK(+) cells were examined for CD44 and CD24 expression by light microscopy, fluorescence microscopy, and spectral imaging.
  
  
  RESULTS
  We detected the putative stem cell-like phenotype in all CK(+) specimens. The mean prevalence of putative stem/progenitor cells was 72% and median prevalence was 65% (range, 33-100%) among the overall DTC per patient, compared with primary tumors where this phenotype is reported in <10% of cells.
  
  
  CONCLUSIONS
  This is the first evidence of the existence of the putative stem-like phenotype within the DTC in bone marrow in early breast cancer patients. All patients had a putative stem cell phenotype among the DTC and most individual DTC showed such phenotype. Future molecular characterization of these cells is warranted.
authors.affiliation: Department of Pathology, Keck School of Medicine, University of Southern California, 2011 Zonal Avenue, Los Angeles, CA 90033, USA.
authors.forename: Marija
authors.initials: M
authors.lastname: Balic
authors.forename: Henry
authors.initials: H
authors.lastname: Lin
authors.forename: Lillian
authors.initials: L
authors.lastname: Young
authors.forename: Debra
authors.initials: D
authors.lastname: Hawes
authors.forename: Armando
authors.initials: A
authors.lastname: Giuliano
authors.forename: George
authors.initials: G
authors.lastname: McNamara
authors.forename: Ram H
authors.initials: RH
authors.lastname: Datar
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cote
mesh_terms: D001853:Bone Marrow / Q000378:metabolism / Q000473:pathology*; D001856:Bone Marrow Examination; D019046:Bone Marrow Neoplasms / Q000556:secondary*; D001943:Breast Neoplasms / Q000473:pathology*; D051927:CD24 Antigen / Q000378:metabolism; D005260:Female; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000473:pathology*; D010641:Phenotype
chemical_list: D051927:CD24 Antigen; D018960:Hyaluronan Receptors; D007633:Keratins