title: Young investigator challenge: Application of cytologic techniques to circulating tumor cell specimens: Detecting activation of the oncogenic transcription factor STAT3.
abstract: BACKGROUND
  The circulating tumor cell (CTC) field is rapidly advancing with the advent of continuously improving technologies for enriching these rare neoplastic cells from blood. CTC enumeration provides prognostic information, and CTC characterization has the potential to provide more useful information for the clinical decision-making process in this era of personalized medicine and targeted therapeutics. Proof-of-principle studies have shown that CTC samples can be characterized with a variety of techniques in the research laboratory environment. The goal of the current study was to validate routine cytologic techniques and immunohistochemical markers in CTC samples in a clinical cytology laboratory, using inducible phosphorylated signal transducer and activator of transcription 3 (pSTAT3) as a clinically important example and Ki-67 as a positive control.
  
  
  METHODS
  Whole blood from noncancer patients was spiked with breast cancer cell lines with constitutive or inducible pSTAT3 expression and underwent CTC processing in the CellSearch system. The resulting CTC samples were subjected to various cytologic/immunocytochemical techniques and were compared with non-CTC-processed cultured cell controls.
  
  
  RESULTS
  CTC-processed samples showed a morphology comparable to that of controls in cytospin, ThinPrep, and cell block preparations. Immunocytochemistry for Ki-67 and pSTAT3 provided biological information from CTC samples, showing uniform Ki-67 staining across all samples, pSTAT3 positivity in the constitutive and induced cells, and an absence of pSTAT3 expression in the noninduced cells, as expected.
  
  
  CONCLUSIONS
  CTC samples can be processed in the cytology laboratory with routine methods. CTC morphologic and immunophenotypic analysis can be easily integrated into the existing clinical workflow, moving the field closer to a true peripheral blood liquid biopsy for cancer patients.
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.|Harvard Medical School, Boston, Massachusetts.
authors.forename: Alarice C
authors.initials: AC
authors.lastname: Lowe
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Pignon
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Carvo
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.|Harvard Medical School, Boston, Massachusetts.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Drage
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Natalie M
authors.initials: NM
authors.lastname: Constantine
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts.
authors.forename: Nichole
authors.initials: N
authors.lastname: Jones
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts.
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Kroll
authors.affiliation: Harvard Medical School, Boston, Massachusetts.|Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts.
authors.forename: David A
authors.initials: DA
authors.lastname: Frank
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.|Harvard Medical School, Boston, Massachusetts.
authors.forename: Sabina
authors.initials: S
authors.lastname: Signoretti
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.|Harvard Medical School, Boston, Massachusetts.
authors.forename: Edmund S
authors.initials: ES
authors.lastname: Cibas
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D003581:Cytodiagnosis / Q000379:methods*; D003584:Cytological Techniques / Q000379:methods*; D006801:Humans; D007150:Immunohistochemistry; D009360:Neoplastic Cells, Circulating; D050796:STAT3 Transcription Factor / Q000032:analysis*
chemical_list: D014408:Biomarkers, Tumor; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human
keywords: circulating tumor cell (CTC); cytological techniques; cytology; immunocytochemistry; signal transducer and activator of transcription 3 (STAT3)