Effect of laparotomy and laparoscopy on the establishment of lung metastasis in a murine model

Laparoscopic surgery is now applied to patients with gastrointestinal cancer. In animal studies, extraperitoneal tumor growth has been significantly less after laparoscopy than after laparotomy, but whether hematogenous metastasis occurs less frequently after laparoscopy is unknown. The aim of this study was to compare the frequency and growth of lung metastasis and serum levels of IL-6 and tumor necrosis factor-alpha (TNF-alpha) in mice treated by laparotomy and in mice treated by laparoscopy.

We used 182 male BALB/c mice. Colon 26 cancer cells (5 x 10(4)) were injected into the tail vein, and the mice were assigned to a laparotomy group (3-cm laparotomy), a laparoscopy group (carbon dioxide pneumoperitoneum at 6 to 8 mm Hg for 30 minutes), or a control group. Lung weight, number of lung metastases, and serum levels of IL-6 and TNF-alpha were measured and compared among the 3 groups.

The lung weight and number of metastases on the lung surface and cut section in the laparotomy group (0.44+/-0.21 g, 55.7+/-46.7, 23.0+/-19.0) were significantly larger than those in the laparoscopy group (0.32+/-0.15 g, 29.9+/- 25.5, 13.1+/-9.9) or the control group (0.28+/-0.13, 29.3+/-26.2, 11.1+/-11.1). Three hours after the procedures, the serum level of IL-6 was significantly higher in the laparotomy group (1353 +/- 790 pg/mL) than in the laparoscopy group (671+/-353 pg/mL) or the control group (333+/-341 pg/mL). The lung weight, number of lung metastases, and levels of IL-6 and TNF-alpha were not different between the laparoscopy and control groups.

Our results indicate that, although laparotomy accelerates tumor metastasis to the lung in this murine model, laparoscopy does not increase the frequency and growth of lung metastasis. The laparoscopic approach may suppress hematogenous metastasis to the lung because of decreased surgical stress and reduced cytokine response.