title: Surgery promotes implantation of disseminated tumor cells, but does not increase growth of tumor cell clusters.
abstract: BACKGROUND
  Local recurrence and peritoneal dissemination is common after intentionally curative resection of colorectal carcinoma. It is not yet clear which mechanisms stimulate post-operative intra-abdominal tumor development. Enhanced adhesion or growth of tumor cells and/or post-operative immuno suppression may influence tumor recurrence.
  
  
  OBJECTIVE
  In the present study, we evaluated effects of local and remote surgery on intra-abdominal tumor development.
  
  
  METHODS
  A standardized intra-abdominal trauma was inflicted by rubbing both uterus horns in laparotomy groups, while a dorsolateral thoracotomy was performed in thoracotomy groups (on day -1, 0, or +3). To induce tumor development rats were injected intra-peritoneally with the coloncarcinoma cell line CC531s on day 0 and evaluated after 21 days.
  
  
  RESULTS
  Rats undergoing laparotomy and injection on day 0 showed significantly higher tumorload than control rats (195 +/- 20 vs. 47 +/- 29, P < 0.001). When a laparotomy was performed, the day before tumor inoculation even higher tumorload was seen (245 +/- 37 vs. 195 +/- 20, P < 0.01). Strikingly, performing a thoracotomy on the day before or on the same day as tumor inoculation resulted in enhanced tumorload compared to controls as well (135 +/- 84 vs. 47 +/- 29; P < 0.001 and 88 +/- 38 vs. 47 +/- 29; P < 0.02, respectively). Either laparotomy or thoracotomy 3 days after tumor cell inoculation did not affect growth of pre-existing tumor cell clusters.
  
  
  CONCLUSIONS
  The (post) surgical intra-peritoneal microenvironment enhances successful implantation of spilled tumor cells, whereas growth of adhered tumor cell clusters is not affected. The inflammatory response as a result of remote surgery promotes successful tumor development as well.
authors.affiliation: Department of General Surgery, ErasmusMC, Rotterdam, The Netherlands.
authors.forename: S Ten
authors.initials: ST
authors.lastname: Raa
authors.forename: S J
authors.initials: SJ
authors.lastname: Oosterling
authors.forename: N P
authors.initials: NP
authors.lastname: van der Kaaij
authors.forename: M P
authors.initials: MP
authors.lastname: van den Tol
authors.forename: R H J
authors.initials: RH
authors.lastname: Beelen
authors.forename: S
authors.initials: S
authors.lastname: Meijer
authors.forename: C H J
authors.initials: CH
authors.lastname: van Eijck
authors.forename: J R M
authors.initials: JR
authors.lastname: van der Sijp
authors.forename: M
authors.initials: M
authors.lastname: van Egmond
authors.forename: J
authors.initials: J
authors.lastname: Jeekel
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000601:surgery; D000818:Animals; D002448:Cell Adhesion; D002452:Cell Count; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000473:pathology* / Q000601:surgery; D005260:Female; D007813:Laparotomy; D009366:Neoplasm Seeding; D009368:Neoplasm Transplantation; D010534:Peritoneal Neoplasms / Q000473:pathology*; D011183:Postoperative Complications / Q000209:etiology / Q000473:pathology*; D051381:Rats; D011919:Rats, Inbred Strains; D013908:Thoracotomy