Enhanced tumour growth and impaired cellular antitumoural defence in hepatic colorectal carcinoma metastasis in rats after laparoscopy compared to open surgery

Background: This study aims to assess postoperative hepatic growth of colorectal adenocarcinoma metastasis and peritumoural macrophage counts after laparoscopy in an experimental animal model. Methods: Thirty male syngenic WAG/Rij rats were randomised into two surgical groups: laparoscopy (LS; n = 15) using CO2 at 12 mmHg and laparotomy (LT; n = 15; negative control) during an operating time of 90 min. At 45 min after setup, CC531s colon adenocarcinoma cells were injected into two liver lobes. Postoperative tumour volumes were determined by abdominal magnetic resonance imaging (MRI) and computed three-dimensional volumetry. Peritumoural macrophages were counted by local stereology using a confocal laser-scanning fluorescence microscope. Results: The median postoperative tumour volume was significantly higher after LS in both lobes (L): after 10, 15 and 20 days in L2 and L5: 24/12, 54/38, 275/62 mm(3) and 0/0, 15/11, 55/24 mm(3) (LS/LT). Significantly fewer peritumoural macrophages were found after LS at all postoperative time points (Mann-Whitney: p < 0.05). Conclusions: Increased hepatic growth of colorectal adenocarcinoma metastasis and impaired cellular antitumoural defence after LS cast doubt on the use of LS in colorectal cancer and needs further clinical investigation.