Impact of pneumoperitoneum on trocar site implantation of colon cancer in hamster model

BACKGROUND: Numerous anecdotal reports have documented the spread of colon cancer to trocar sites after laparoscopic-assisted colectomy. We hypothesized that the pneumoperitoneum of laparoscopy potentiated tumor adherence to trocar sites. PURPOSE: This study was designed to determine the affect of CO₂pneumoperitoneum on the rate of tumor implantation at trocar sites. METHODS: Viable GW-39 human colon cancer cells were injected into the abdominal cavity of hamsters (2 × 10⁶cells/hamster). A midline laparotomy, insertion of four 5-mm trocars, injection of viable cells into the mesentery of the cecum, and free peritoneal cavity was performed in two groups: one control group (41) who did not receive a pneumoperitoneum and a comparison group (50) who underwent pneumoperitoneum for ten minutes at an insufflation pressure of 10 mmHg. Animals were killed at six weeks, and hematoxylin and eosin-stained sections of trocar wounds, midline wound, small intestine, cecum, liver, and lung were examined by a veterinary pathologist, who was blinded to operation. RESULTS: Pneumoperitoneum increased tumor implantation in the cecal mesentery and the midline incision (P<0.05) but did not effect recurrence in the liver, lung, or jejunum. Trocar site implantation tripled with the addition of pneumoperitoneum (26vs. 75 percent) (P<0.0001). CONCLUSION: Pneumoperitoneum increased implantation of free intra-abdominal cancer cells at wound sites on the abdominal wall or within the abdominal cavity in this animal model. The use of pneumoperitoneum during laparoscopy in patients with colon cancer should only be performed in a protocol setting to evaluate the effect of pneumoperitoneum on the treatment of cancer.