Impact of surgical peritoneal environment on postoperative tumor growth and dissemination in a preimplanted tumor model

Abstract

We recently demonstrated that CO(2) pneumoperitoneum at low intraperitoneal pressure (IPP) had few if any short-term effects on peritoneal dissemination when an ovarian cancer cell line was inoculated just prior to surgery. The objective of the present study was to evaluate the impact of surgical peritoneal environment on postoperative tumor growth and dissemination over time when tumors were present before surgery. On day-7, C57BJ6 mice received an intraperitoneal inoculation of a mouse ovarian cancer cell line (ID8). On day 0, mice were randomized into four groups: anesthesia alone, CO(2) pneumoperitoneum at a low (2 mmHg) or high (8 mmHg) IPP, or laparotomy. Groups were further subdivided into four groups of eight animals each and a laparotomy was performed to evaluate dissemination on postoperative day (POD) 1, 2, 7 or 14. Peritoneal dissemination score was significantly higher in the laparotomy group compared with in the remaining three groups on PODs 2 and 7. We detected no significant differences in the peritoneal dissemination scores among the low-IPP, high-IPP, and anesthesia groups on PODs 2 and 7. However, there were no significant differences in the peritoneal dissemination score among the three surgical groups on POD 14. Histopathological examination demonstrated that the incidence of invasion of cancer cells into the muscle layers was significantly higher in the laparotomy group than in the low-IPP and anesthesia groups on POD 14. There were no significant differences in tumor growth among the four groups. The present findings suggest that CO(2) pneumoperitoneum at either high or low IPP has few if any short-term effects on peritoneal dissemination when tumors are well established before surgery.