Impact of pneumoperitoneum on visceral metastasis rate and survival. Results in two ovarian cancer models in rats

Objective To compare the impact of CO2 laparoscopy, gasless laparoscopy, and midline laparotomy on the development of distant metastases and on survival in two ovarian carcinoma models. Design A prospective randomised study in rats. Material and methods Two ovarian cancer xenografts were obtained by intraperitoneal injection of IGR–OV1 or NIH–OVCAR‐3 cells. Experimental surgical procedures were performed on day 7 (IGR–OV1 model) or day 14 (NIH: OVCAR‐3 model) after intraperitoneal injection: CO2 laparoscopy (pneumoperitoneum (PNP) with unheated CO2 at a pressure of 8 mmHg for 1 hour); gasless laparoscopy (consisting in abdominal wall expansion by a balloon for 1 hour); midline laparoscopy (consisting in bowel exteriorisation on a mesh for one hour following xyphopubic laparotomy). The control group underwent general anaesthesia alone. The animals were killed by CO2 inhalation as soon as they became moribund. Main outcome measures Pathological examination was carried out on the liver, lungs and pleura as well as the retroperitoneal nodes. Survival was determined from the time of surgery to the sacrifice of the animal. Statistical analysis used ANOVA, Fisher exact test, Bonferonni method and the log‐rank test. Results In the IGR–OV1 model, distant metastases were rare, and were not promoted by CO2 laparoscopy. With the NIH: OVCAR‐3 model, pleural, pulmonary and para‐aortic metastases were not enhanced by CO2 PNP when compared with other approaches. Conversely, midline laparotomy and laparoscopy significantly increased liver involvement when compared with gasless laparoscopy (P= 0.04 and P= 0.008). Survival was comparable no matter what kind of surgery had been performed in the IGR–OV1 model (P= 0.7) or in the NIH: OVCAR‐3 model (P= 0.5). Conclusions CO2 laparoscopy had a minor impact on distant and nodal metastases in the two models. Similarly, survival was similar for all surgical groups.