Minimally invasive colorectal resection for cancer is associated with a short-lived decrease in soluble Tie-2 receptor levels, which may transiently inhibit VEGF-mediated angiogenesis (via altered blood levels of free Ang-1 and Ang-2)

Background: Angiopoetin- (Ang-) 1 inhibits and Ang-2 promotes VEGF-mediated angiogenesis via binding to endothelial cell-bound Tie-2 receptor (Tie-2). After minimally invasive colorectal resection (MICR), Ang-1 levels decrease and Ang-2 levels increase, which may stimulate angiogenesis in wounds and residual tumor foci. Soluble Tie-2 (sTie-2) modulates the effects of free Ang-1 and Ang-2 by binding to them. This study assessed perioperative MICR plasma sTie-2 levels. Methods: Blood samples were taken preoperatively (PreOp) and on postoperative days (POD) 1 and 3 from 50 cancer and 53 benign disease MICR patients. In a subgroup, a fourth sample was taken between POD7 and POD13 and bundled as a single time point. sTie-2 levels (ng/ml) were determined via ELISA. The mean and SD were determined at each time point. The t test used for analysis. Results: PreOp plasma sTie-2 levels were significantly higher in the benign group (27.6 ± 10.2) than in the cancer group (22.9 ± 7.9). A significant drop from PreOp occurred in sTie-2 levels in the cancer group on POD1 (20.0 ± 7.4) and POD3 (21.0 ± 6.6) and in the benign group on POD1 (24.8 ± 9.1). The benign group's POD3 and the cancer group's POD7-13 sTie-2 levels were statistically similar to the PreOp levels while the benign group's POD7-13 level was significantly higher. Conclusion: PreOp sTie-2 levels were significantly lower in cancer patients. MICR is associated with a significant short-lived decrease in plasma sTie-2 levels in cancer patients on POD1 and 3, which may briefly inhibit VEGF-mediated angiogenesis. The benign group's early results were similar.