Experimental assessment of tumor growth and dissemination of a microscopic peritoneal 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, laparoscopic surgery for malignant disease is regarded as controversial. We used a rat model to measure and compare the tumor growth, proliferation, and dissemination of a microscopic peritoneal carcinomatosis after CO2 intraperitoneal 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 aneuploid tumor cell line. At 48 h after tumor cell injection, the animals were randomly divided into three groups to undergo different types of intervention. All animals were anesthetized for 20 min (Halothane). The control group had no surgical intervention (group C), group I had CO2 insufflation (7 mmHg),and group L had a midline laparotomy (5-cm). Neither bowel manipulation nor any other traumatic action was performed. Two weeks later, the rats were killed and the incidence, type, and dissemination of carcinomatosis were evaluated. We also measured the tumor's weight. Malignant omentum was sampled for flow cytometry analysis (DNA ploidy, S-phase fraction). Results: The incidence of carcinomatosis did not differ among the groups. The 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 group 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 more effects than laparotomy when tumors cells are present before the beginning of the surgery. Further studies are needed to determine the influence of other steps in laparoscopic surgery on tumor growth and dissemination.