Experimental assessment of tumor growth and dissemination of a microscopicperitoneal carcinomatosis after CO2 peritoneal insufflation or laparotomy - Clinical and biological results of a randomized animal study

Background: Based on clinical observations and previous animal studies, lap aroscopic surgery for malignant disease is regarded as controversial. We us ed a rat model to measure and compare the tumor growth, proliferation, and dissemination of a microscopic peritoneal carcinomatosis after CO2 intraper itoneal insufflation or laparotomy. Methods: Peritoneal carcinomatosis was induced in three groups of 27 BD IX rats each with intraperitoneal injections of 10(6) DHD/K12 cells, an aneupl oid tumor cell line. At 48 h after tumor cell injection, the animals were r andomly divided into three groups to undergo different types of interventio n. All animals were anesthetized for 20 min (Halothane). The control group had no surgical intervention (group C), group I had CO2 insufflation (7 mmH g),and group L had a midline laparotomy (5-cm). Neither bowel manipulation nor any other traumatic action was performed. Two weeks later, the rats wer e killed and the incidence, type, and dissemination of carcinomatosis were evaluated. We also measured the tumor's weight. Malignant omentum was sampl ed for flow cytometry analysis (DNA ploidy, S-phase fraction). Results: The incidence of carcinomatosis did not differ among the groups. T he mean score of macroscopic characteristics of the carcinomatosis was 2.8 +/- 1.9 in group L. 2.9 +/- 1.9 in group I, and 3 +/- 1.9 in group C (NS). The location of the implants did not differ, except for parietal peritoneum location, which was more frequent in group L (p < 0.01). The tumor weight was 4.96 +/- 3.2 in group L, 5.55 +/- 3.2 in group C, and 5.75 +/- 3.4 in g roup I (NS). The percentage of aneuploid cells and S-phase fraction did not differ statistically among the groups. Conclusion: These results indicate that CO2 insufflation does not cause mor e effects than laparotomy when tumors cells are present before the beginnin g of the surgery. Further studies are needed to determine the influence of other steps in laparoscopic surgery on tumor growth and dissemination.