Variables in the spread of tumor cells to trocars and port sites during operative laparoscopy

BACKGROUND: Port-site recurrences have delayed the uptake of laparoscopic colectomy, but the etiology of these is incompletely understood. These studies were designed to investigate variables such as the size of the tumor inoculum and the volume and pressure of the insufflated gas during operative laparoscopy that might affect the deposition of these cells in relation to trocars and port sites. METHODS: Radiolabeled human colon cancer cells were injected into the peritoneal cavity of pigs. Three trocars were inserted, and the abdomen was insufflated with carbon dioxide. The movement of cells within the abdomen was traced on a gamma camera. After 2 h, the trocars were removed and the port sites excised. Two studies were performed. In the first study, tumor inocula were varied from 1.5 × 105 to 120 × 105. In the second study, insufflation pressure was varied, with pressures 0, 4, 8 and 12 mmHg were studied. RESULTS: When larger tumor inocula were injected, the contamination of both trocars (p = 0.005, Kendall's rank correlation) and trocar sites (p = 0.04, Kendall's rank correlation) increased. The deposition of cells on a trocar site was linked to contamination of its trocar (p = 0.03, chi-square), but the contamination of trocars did not always result in trocar-site contamination (p = 0.5, chi-square). Increased volumes of gas insufflation caused increased intraabdominal movement of tumour cells (p = 0.01, Kendall's rank correlation), although this did not lead to greater contamination of trocars or port sites (p = 0.82, Kendall's rank correlation). Decreased insufflation pressures resulted in increased contamination of trocars and port sites (p = 0.01, Kendall's rank correlation). CONCLUSIONS: If clinical situations parallel this study, strategies such as increasing insufflation pressure, reducing episodes of desufflation and gas leaks, and using frequent intraabdominal lavage may help to reduce the numbers of viable tumor cells displaced to port sites during laparoscopic surgery for intraabdominal malignancy. This may reduce the rate of port-site metastases.