Abdominal insufflation does not cause hematogenous spread of colon cancer

Background and Purpose: Previous investigators have suggested that port- site recurrences are possibly a result of abdominal insufflation, forcing viable cancer cells into the circulation to metastasize and thrive in areas of trauma. Using a syngeneic animal cancer model, we tested the hypothesis that pneumoperitoneum increases the incidence of wound metastasis by a blood- borne mechanism. Methods: Male BD IX rats (N = 150) were injected intraperitoneally with 2 x 10⁵ viable syngeneic 1,2-dimethylhydralazine- induced colon cancer cells (DHD-K12). Animals were divided into three groups: A (abdominal insufflation with 3-cm incision on the back into muscle remote from the peritoneum); B (3-cm back incision alone); and C (control group with 3-cm midline abdominal incision). Three weeks after surgery, the animals were euthanized and autopsied. Results: In the two groups with back wounds, the incidence of cancer growth at the incision was zero, as demonstrated grossly and by histologic sample (A: 0/47, B: 0/43). In contrast, the autopsied control group had a 42% incidence of metastasis to the wound (25/59). There seemed to be no difference in the distribution of intra-abdominal disease between those rats that underwent insufflation and those that did not. Conclusion: It is unlikely that pneumoperitoneum promotes hematogenous wound implantation of free intraperitoneal cancer cells.