title: Flow cytometric quantification of intraperitoneal free tumor cells in patients with peritoneal metastasis.
abstract: BACKGROUND
  Peritoneal metastasis (PM) is the most life-threatening type of metastasis in abdominal malignancy. To improve the diagnostic accuracy of cytologic detection (CY) of free tumor cells (FTC) in the peritoneal cavity, we tried to quantify the FTC to leukocyte ratio using flow cytometry in patients with peritoneal metastasis.
  
  
  METHODS
  Cells were recovered from ascites or peritoneal lavages from 106 patients who underwent abdominal surgery and additional 89 samples which were obtained from peritoneal catheter or access port in patients with PM (+) gastric cancer. The cells were immunostained with monoclonal antibodies to CD45 and to CD326 (EpCAM). Using flow cytometry, CD326 (+) and CD45 (+) cells were classified as either tumor cells (T) or leukocytes (L) and the T/L ratio (TLR) was calculated.
  
  
  RESULTS
  In 106 samples obtained by laparotomy, Median (M) of the TLR of PM (+) patients was 1.39% (0-807.87%) which was significantly higher than PM (-) patients (M=0%, 0-2.14%, P < 0.001). In PM (+) patients, 86 CY (+) samples showed higher TLR than 61 CY (-) samples (M=2.81%, 0.02-1868.44% vs. M=0%, 0-3.45%, p<0.0001). In all of the 24 patients who were monitored for TLR before and after intraperitoneal (IP) chemotherapy, the TLR was reduced which was more dramatic than the results of the change in cytology.
  
  
  CONCLUSIONS
  TLR measured with FACS is an excellent reflection of the tumor spread in the peritoneal cavity and could be a reliable diagnostic biomarker to determine the severity of PM as well as effectiveness of IP chemotherapy.
authors.affiliation: Department of Surgical Oncology, University of Tokyo, Tokyo, Japan.
authors.forename: Joji
authors.initials: J
authors.lastname: Kitayama
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Emoto
authors.forename: Hironori
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Hironori
authors.initials: H
authors.lastname: Ishigami
authors.forename: Takao
authors.initials: T
authors.lastname: Kamei
authors.forename: Hiroharu
authors.initials: H
authors.lastname: Yamashita
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Seto
authors.forename: Keisuke
authors.initials: K
authors.lastname: Matsuzaki
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology; D001202:Ascitic Fluid / Q000166:cytology*; D015815:Cell Adhesion Molecules / Q000276:immunology; D000071858:Epithelial Cell Adhesion Molecule; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D017493:Leukocyte Common Antigens / Q000276:immunology; D007962:Leukocytes; D009360:Neoplastic Cells, Circulating; D010529:Peritoneal Cavity / Q000166:cytology*; D010533:Peritoneal Lavage; D010534:Peritoneal Neoplasms / Q000175:diagnosis* / Q000556:secondary; D013274:Stomach Neoplasms / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules; D000071858:Epithelial Cell Adhesion Molecule; D017493:Leukocyte Common Antigens; C516769:PTPRC protein, human
keywords: CD326; flowcytometry; intraperitoneal free tumor cell; peritoneal cytology; peritoneal metastasis