INCREASED TUMOR ESTABLISHMENT AND GROWTH AFTER LAPAROTOMY VS LAPAROSCOPY IN A MURINE MODEL

Objective: To test our hypothesis that tumors would be more easily est ablished and grow more aggressively after laparotomy than after laparo scopy. This hypothesis was based on studies that have demonstrated tha t surgery can suppress immune function and facilitate tumor growth and that have shown preservation of immune function after laparoscopic pr ocedures. Design: Double-blinded, randomized, control trial. Setting: Research laboratory and animal care facility. Animals: One hundred for ty 5- to 6-week-old C3H/He female mice. Interventions: Three experimen ts with three groups each: laparotomy, insufflation, and anesthesia co ntrols. All animals received an intradermal inoculation of tumor cells in the dorsal skin. The anesthesia control cohort underwent no proced ure. The laparotomy cohort underwent a midline laparotomy from the xip hoid process to the pubis, which was closed after 30 minutes. The insu fflation cohort underwent peritoneal insufflation with carbon dioxide for 30 minutes. Main Outcome Measures: Tumor volume, tumor mass, and i ncidence of tumor establishment. Results: In the first experiment, the tumor volumes of the anesthesia control and insufflation groups follo wed a similar pattern of plateau and regression. The tumor volumes of the laparotomy group followed a different pattern and were significant ly larger than those of the control and insufflation groups on postope rative days 6 and 12 (P<.05 for all comparisons). In the second experi ment, tumors in the laparotomy group were approximately three times la rger than those of the control group (P<.01) and almost twice as large as insufflation group tumors (P<.01) by mass. In the third experiment , there was a significantly higher incidence of tumor establishment in the laparotomy group than in the insufflation (P<.04) or control (P<. 01) groups. The incidence was not different between the control and in sufflation groups. Conclusions: Tumors were more easily established an d grew more aggressively after laparotomy than after insufflation. The se results, coupled with those that demonstrate an immune advantage to laparoscopy over laparotomy, suggest that the difference in observed tumor growth may be related to immune function. While much work remain s to be done, we believe these data provide evidence of a previously u ndemonstrated benefit of laparoscopic intervention.