We investigated the effects of laparotomy and insufflation on tumor establishment and growth in a murine model. Twenty female mice received intradermal inoculation of a low dose of tumor cells (2 x 103) derived from the MC2 mouse mammary carcinoma cell line. Ten of these mice underwent laparotomy and ten received intraperitoneal insufflation with carbon dioxide gas at a pressure of 5 mmHg for 30 rain. Tumor growth was followed postoperatively. By postoperative day 14, tumors had grown in zero of the ten insuffiated mice and in seven of the ten laparotomygroup mice (P < 0.005). By postoperative day 30, tumors had grown in one of the ten insuffiated mice and in eight of the ten laparotomy-group mice (P < 0.007).
Ten additional mice received a high-dose inoculum of cells (1 x 10 6) followed by either laparotomy or intraperitoneal insufflation. Upon sacrifice 12 days later, all mice had developed tumors, but the laparotomy group's tumors were almost three times as large, by mass, as tumors in the insufflated group (70.5 _+ 23.5 mg vs 25.8 ---9.5 mg; P < 0.02).
These results suggest that laparotomy confers a permissive effect on tumor establishment and growth in a murine model not seen after peritoneal insufflation. We hypothesize that this may be a function of relative immunosuppression following laparotomy which is not present following peritoneal insuffiation. These data may be important when choosing a route of access to the peritoneal cavity for cancer resection.