Effect of CO2 pneumoperitoneum on growth of liver micrometastases in a rabbit model

Little is known about the risk of metachronous liver metastases following laparoscopic resection for gastrointestinal malignancies. The effect of CO2 pneumoperitoneum on the growth of established liver micrometastases was investigated in a rabbit model. Male Japanese white rabbits weighing 2.8 to 3.3 kg were randomized to three groups (n = 15 per group) 3 days following intraportal inoculation of a tumor suspension containing 5 x 10(4) cells of VX2 cancer. In the pneumoperitoneum group, insufflation with CO2 was maintained at a pressure of 10 mmHg for 30 minutes. In the laparotomy group the abdominal cavity remained open through a 45 mm midline incision for 30 minutes; in the control group no treatment other than anesthesia was performed. Cancer nodules on the liver surface were compared among the three groups on day 17. There was no difference in the number of cancer nodules among the groups (p = 0.72). A significant difference in the total area of cancer nodules (mean +/- SEM) was found only between the pneumoperitoneum group (696.0 +/- 177.0 mm(2)) and the control group (247.2 +/- 60.7 mm(2)) (p < 0.05), The frequency of cancer nodules larger than 3.0 mm in maximal diameter tended to be highest in the pneumoperitoneum group (p = 0.053), These results suggests that CO2 pneumoperitoneum may promote the growth of established liver micrometastases in this animal model.