Effect of pneumoperitoneum induced by carbon dioxide and air on tumor load in a rat model

Laparoscopic surgery for malignant disease is highly controversial mainly due to the large number of abdominal wall metastases being reported. Previous experimental studies have particularly studied CO2 pneumoperitoneum and its effect on tumor development, The purpose of this study was to compare CO2- and air-induced pneumoperitoneum with regard to intraperitoneal tumor growth. Altogether 39 rats were injected intraperitoneally with 10(5) colonic tumor cells and randomly allocated into three groups: 13 rats had a pneumoperitoneum created with CO2, 13 with air, and 13 served as controls. Tumor development was determined semiquantitatively by a peritoneal cancer index scale after 12 days. CO2 and air pneumoperitoneum equally increased intraperitoneal tumor growth compared to controls. Pneumoperitoneum induced by CO2 and air seems to increase tumor load, but the mechanisms are not established, This finding supports the hypothesis that insufflation not only by causing tumor cell movements but in fact pneumoperitoneum per se and the used gas are involved in the development of abdominal wall metastases after laparoscopic surgery.