Increased tumor establishment and growth after open vs laparoscopic surgery in mice may be related to differences in postoperative T-cell function

Background: Previous work has demonstrated that cell-mediated immune functi on in rats is better preserved after laparoscopic than open surgery. We hav e also shown that tumors are more easily established in mice and grow large r after sham laparotomy than after pneumoperitoneum. The purpose of this st udy is to determine if the functional status of the cell-mediated immune sy stem influences postoperative tumor growth. Methods: Immunocompetent (study 1) and T-cell deficient athymic (study 2) m ice were injected with mouse mammary carcinoma cells in the dorsal skin. Mi ce then underwent either no procedure, midline laparotomy, or carbon dioxid e pneumoperitoneum. Tumor masses on postoperative day 12 were compared. Results: In immunocompetent mice, laparotomy group tumors were nearly twice as large as laparoscopy group tumors (p < 0.02), which were 1.5 times as l arge as control group tumors (NS). In the athymic model, however, differenc es between the sham laparotomy and pneumoperitoneum groups were lost (p > 0 .5). Tumors grew much larger in the athymic control mice than in the immuno competent control mice (p < 0.01). Conclusion: We conclude that T-cell function plays a significant role in ho st containment of mouse mammary carcinoma and in the mechanism of differenc es in tumor growth observed after laparotomy and pneumoperitoneum.