Background: Port-site metastases after laparoscopic procedures in patients with digestive malignancies have evoked concern. The pathogenesis of port-site metastases remains unclear. Two experiments in rats were performed to determine the impact of both tissue trauma and leakage of CO2 along trocars (chimney effect) in the development of port-site metastases.
Methods: Experiment I: Ten WAG rats had four 5-mm incisions in all abdominal quadrants. The incisions on the right side were crushed to induce tissue trauma. After inserting 5-mm trocars in all incisions, a pneumoperitoneum was created, and CC-531 tumor cells were injected intraperitoneally. CO2 was insufflated for 20 min. Experiment II: Ten WAG rats had 5-mm incisions in the left and right abdominal upper quadrant. A 5-mm trocar was inserted in the incision in the left upper quadrant, and a 2-mm trocar was inserted in the incision in the right upper quadrant. After insufflating the abdomen, CC-531 tumor cells were injected intraperitoneally. Total leakage of CO2 along the trocar in the right quadrant was 10 liters. After 4 weeks, in both experiments, the tumor deposits at the trocar sites were assessed. Statistical analysis was performed by the Wilcoxon matched-pairs test.
Results: Experiment I: The median weight of tumor deposits at the trocar sites without induced tissue trauma was 22 mg. At the traumatic port sites, median weight of tumor deposits was 316 mg (p = 0.007). Experiment II: The median weight of tumor deposits at the leaking trocar sites was 478 mg and at the control sites 153 mg (p = 0.009).
Conclusion: Tissue trauma at trocar sites and leakage of CO2 along a trocar appear to promote implantation and growth of tumor cells at port sites.