Influence Of CO₂ Pneumoperitoneum On Port-site Recurrences After Laparoscopic Surgery For Cancer

Background: The port-site recurrences (PSRs) after carbon dioxide (CO₂)pneumoperitoneum-based laparoscopic surgery for malignant diseases has been well concerned. PSRs is a kind of cancer recurrences that develop locally in the abdominal wall incision wound. So far, there are numerous PSRs case reports. The accumulation of such reports in a relatively short period raised concern that there might be an extraordinary high rate of wound recurrences after laparoscopic cancer surgery and the mechanism of PSRs has not been fully understood.Objectives:1. To compare the incidence rate of abdominal wall wound recurrences after laparoscopic surgery for colorectal carcinoma that of open surgery.2. To observe the influence of CO₂ on the growth, migration andthe expression the HIF-lamRNA of human hepatocarcinoma cell line HepG2 in vitro.Methods:1. Medline and China Academic Journal Full-text Database search was conducted for the published non-randomized controlled trails and randomized controlled trails of C02 pneumoperitoneum-based laparoscopic versus open surgery for the colorectal carcinoma from 01/1990 to 04/2005. Articles reporting the rate of wound recurrences of both group and the working space for laparoscopic group established by C02 pneumoperitoneum were included. Data synthesis and analysis were performed by the RevMan 4.2 software downloaded from the website of Cochrane organization.2. The human hepatocarcinoma cell line HepG2 was exposed to 100% C02, 100% nitrogen (N2) and normal culture condition respectively for 3 hours. After exposure cell proliferation was assessed by CCK-8 assay. Cell migration was measured by the agarose droplet migration assay and the expression of HIF-lamRNA was determined by RT-PCR.Results:1. 31 eligible trials (5214 participants) were included for analysis. Among them there were 19 non-randomized controlled trials (non-RCTs) which included 2969 participants and 12 randomized controlled trials (RCTs) which included 2245 participants. Within the follow up period the incidence rate of wound recurrences after laparoscopic surgery was 0. 65% and that after open surgery was 0. 58%. The overall effect of risk difference (RD) was 0.00, 95% confidence interval (CI)was (0.00, 0.01), Z=0. 51, P=0. 61 >0. 05.2. The HepG2 cells growth and migration ability significant increased after exposure to both C02 and N2 environment. The expression of HIF-1 amRNA of HepG2 cells slightly increased after exposure to 100% C02 and to 100% N2 for 3 hours.Conclusions:1. The incidence rate of wound recurrences after laparoscopic surgery for colorectal carcinoma was 0. 65% and that after open surgery was 0. 58%.2. No strong clinical evidence showed that the incidence rate of wound recurrence after laparoscopic surgery based on theC02 pneumoperitoneumwas higher than that after open surgery for colorectal carcinoma.3. C02 and N2 exposure may promote cancer cell growth, migration and the expression of HIF-lamRNA in vitro. These effects were suspected to be associated with hypoxia environment.