Influence of postoperative acute-phase responseon angiogenesis and tumor growth: Open vs. laparoscopic-assisted surgery in mice

Inflammatory responses and tumor growth are increased after laparotomy compared with laparoscopy in some animal models. Proinflammatory cytokines interleukin-6 (IL-6) and interleukin-1 beta (IL-1β) upregulate the expression of vascular endothelial growth factor (VEGF). Our aim was to investigate the influence of postoperative inflammatory responses on angiogenesis and tumor growth. 5×10⁶ B51LiM cells were injected into the cecal wall of Balb/c mice. After 2 weeks, the animals were randomized into the following three groups: open cecectomy (OC), CO ₂-laparoscopic-assisted cecectomy (LC), and helium-laparoscopic-assisted cecectomy (LH). On postoperative day 12, the mice were killed. Tumor load scores and weight were significantly greater after laparotomy than after laparoscopy. Serum IL-6 levels 6 hours after surgery (OC: 4157±1297 pg/ml vs. LC: 2514±1417 pg/ml vs. LH: 2255±1714 pg/ml) and VEGF levels on postoperative day 12 (OC: 231±125 pg/ml vs. LC: 45±9 pg/ml vs. LH: 49±8 pg/ml), measured by enzyme-linked immunosorbent assay, were significantly higher in the laparotomy group. Microvessel density was also significantly higher in the OC group (OC: 34.3±11.5 vs. LC: 15.5±12.5 vs. LH: 18.5±11.9). There was a positive correlation between IL-6 and VEGF postoperative serum levels (rho = 0.67; P<0.001). We concluded that increased systemic levels of proinflammatory cytokines and VEGF are associated with increased angiogenesis and tumor growth after laparotomy compared to laparoscopy in mice.