title: Mechanisms of peritoneal metastasis after operation for non-serosa-invasive gastric carcinoma: an ultrarapid detection system for intraperitoneal free cancer cells and a prophylactic strategy for peritoneal metastasis.
abstract: OBJECTIVE
  This aims of this study are to establish an ultra-rapid quantitative reverse transcription-PCR (RT-PCR) protocol that enables the diagnosis of i.p. cancer spread during operation, to reveal the mechanisms of peritoneal metastasis from non-serosa-invasive gastric carcinoma, and to evaluate the effect of the extensive intraoperative peritoneal lavage (EIPL) using the ultra-rapid quantitative RT-PCR as a prophylactic strategy for peritoneal metastasis.
  
  
  METHODS
  Peritoneal lavage samples from 63 patients with non-serosa-invasive gastric carcinoma were obtained at laparotomy and immediately after lymph node dissection. To identify the free cancer cells in the samples, carcinoembryonic antigen- and cytokeratin 20-specific RT-PCRs were performed using the LightCycler method in combination with an automated mRNA extractor. In addition, EIPL was performed in five cases with serosa-invasive gastric carcinoma, and its efficacy was evaluated by the ultra-rapid quantitative RT-PCR protocol.
  
  
  RESULTS
  The method enabled us to complete the detection of cancer cells within approximately 70 min. Both the carcinoembryonic antigen and cytokeratin 20 mRNA in i.p. lavages after lymph node dissection were identified in three (14.3%), four (26.7%), and six (46.2%) patients with submucosal, muscularis propria, and subserosal tumors, respectively. Lymph node metastasis was the independent predictor of the existence of i.p. free cancer cells. The ultra-rapid quantitative RT-PCR demonstrated that EIPL reduced free cancer cells from 3.8 x 10(5) +/- 1.4 x 10(5) cells to 2.8 +/- 1.5 cells/100 ml lavage after six to eight washes, and they disappeared after seventh to ninth wash.
  
  
  CONCLUSIONS
  The present study proved that lymph node dissection opened lymphatic channels and spread viable cancer cells into the peritoneal cavity. It is suggested that the combination of the novel detection system with the intraoperative therapy of EIPL can be a useful prophylactic strategy for peritoneal metastasis from gastric carcinoma.
authors.affiliation: Department of Surgery II, Kumamoto University School of Medicine, Kumamoto 860-8556, Japan. tmaru10@hotmail.com
authors.forename: Takashi
authors.initials: T
authors.lastname: Marutsuka
authors.forename: Shinya
authors.initials: S
authors.lastname: Shimada
authors.forename: Kenji
authors.initials: K
authors.lastname: Shiomori
authors.forename: Naoko
authors.initials: N
authors.lastname: Hayashi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yagi
authors.forename: Takaaki
authors.initials: T
authors.lastname: Yamane
authors.forename: Michio
authors.initials: M
authors.lastname: Ogawa
mesh_terms: D000368:Aged; D015703:Antigens, CD / Q000235:genetics; D018951:Antigens, CD20 / Q000235:genetics; D001483:Base Sequence; D002272:Carcinoembryonic Antigen / Q000235:genetics; D017931:DNA Primers; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis / Q000517:prevention & control; D010533:Peritoneal Lavage; D010534:Peritoneal Neoplasms / Q000473:pathology* / Q000517:prevention & control / Q000556:secondary*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics / Q000473:pathology / Q000601:surgery*
chemical_list: D015703:Antigens, CD; D018951:Antigens, CD20; D002272:Carcinoembryonic Antigen; D017931:DNA Primers; D012333:RNA, Messenger