PORT-SITE METASTASES - IMPACT OF LOCAL TISSUE TRAUMA AND GAS LEAKAGE

Background: Port-site metastases after laparoscopic procedures in pati ents 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 o f CO2 along trocars (chimney effect) in the development of port-site m etastases. Methods: Experiment I: Ten WAG rats had four 5-mm incisions in all abdominal quadrants. The incisions on the right side were crus hed to induce tissue trauma. After inserting 5-mm trocars in all incis ions, a pneumoperitoneum was created, and CC-531 tumor cells were inje cted 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 uppe r quadrant, and a 2-mm trocar was inserted in the incision in the righ t upper quadrant. After insufflating the abdomen, CC-531 tumor cells w ere injected intraperitoneally. Total leakage of CO2 along the trocar in the right quadrant was 10 liters. After 4 weeks, in both experiment s, the tumor deposits at the trocar sites were assessed. Statistical a nalysis was performed by the Wilcoxon matched-pairs test. Results: Exp eriment I: The median weight of tumor deposits at the trocar sites wit hout induced tissue trauma was 22 mg. At the traumatic port sites, med ian weight of tumor deposits was 316 mg (p = 0.007). Experiment II: Th e 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 tra uma at trocar sites and leakage of CO2 along a trocar appear to promot e implantation and growth of tumor cells at port sites.