title: The effect of peritoneal air exposure on postoperative tumor growth.
abstract: BACKGROUND
  Previous work has demonstrated that cell-mediated immune function is better preserved in rodents after laparoscopic than open surgery. The cause of this laparotomy-related immunosuppression is unclear. Some investigators have attributed it to the length of the incision; others, to peritoneal air exposure. It has also been shown that tumors in mice are more easily established and grow larger after sham laparotomy than after pneumoperitoneum. Lastly, the differences in tumor growth have been shown to be, at least in part, attributable to the immunosuppression that occurs after laparotomy. The purpose of this study was to determine if air pneumoperitoneum, presumably via immunosuppression related to peritoneal air exposure, is associated with increased tumor growth in the postoperative period.
  
  
  METHODS
  A total of 150 immunocompetent syngeneic mice received high-dose intradermal injections of mouse mammary carcinoma tumor cells. They were then randomized to undergo one of the following procedures: (a) anesthesia alone, (b) air insufflation (44 mm Hg), (c) CO2 insufflation, or (d) full laparotomy. No intraabdominal procedure was carried out. All procedures were 20 min long. After 12 days, the animals were killed and the mean tumor mass determined for each group.
  
  
  RESULTS
  All animals grew tumors. There was no significant difference in the mean tumor size of the anesthesia control, CO2 insufflation, and air insufflation groups (p > 0.85 by ANOVA). However, the laparotomy group tumors were 1.5 times as large as those of the other three groups (p < 0.05 by ANOVA).
  
  
  CONCLUSIONS
  In this model, air insufflation did not significantly affect postoperative tumor growth, nor did CO2 pneumoperitoneum. However, full laparotomy was associated with increased tumor growth.
authors.affiliation: Columbia University College of Physicians and Surgeons, Columbia Presbyterian Medical Center, Department of Surgery, New York, NY 10032, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Southall
authors.forename: S W
authors.initials: SW
authors.lastname: Lee
authors.forename: M
authors.initials: M
authors.lastname: Bessler
authors.forename: J D
authors.initials: JD
authors.lastname: Allendorf
authors.forename: R L
authors.initials: RL
authors.lastname: Whelan
mesh_terms: D000388:Air; D000818:Animals; D002245:Carbon Dioxide; D005069:Evaluation Studies as Topic; D005260:Female; D007108:Immune Tolerance; D007121:Immunocompetence; D008325:Mammary Neoplasms, Experimental / Q000601:surgery*; D051379:Mice; D008809:Mice, Inbred C3H; D011028:Pneumoperitoneum, Artificial; D011897:Random Allocation; D014407:Tumor Cells, Cultured
chemical_list: D002245:Carbon Dioxide