Colorectal resection is associated with persistent proangiogenic plasma protein changes: postoperative plasma stimulates in vitro endothelial cell growth, migration, and invasion.

INTRODUCTION: Plasma vascular endothelial growth factor (VEGF) levels are elevated for weeks after minimally invasive colorectal resection (MICR). Decreased plasma angiopoietin-(Ang) 1 and increased Ang-2 levels have been noted on postoperative days (POD) 1 and 3. These proangiogenic changes may stimulate tumor growth postoperatively (postop). This study's purpose was to track plasma VEGF, Ang-1, and Ang-2 levels for 4 to 8 weeks after MICR for cancer and to assess the impact of preoperative (preop) and postop plasma on in vitro endothelial cell (EC) behavior.
METHODS: Blood samples from 105 MICR patients were taken preop, on POD 5 and at varying time points for 2 months. Samples from 7 day time blocks after POD 5 were bundled to permit statistical analysis. Plasma protein levels were measured via enzyme-linked immunosorbent assay. In vitro EC branch point formation, EC invasion, and EC migration assays were carried out with preop, POD 7 to 13 and 14 to 20 plasma. The t test and Bonferonni correction was used.
RESULTS: VEGF levels were significantly elevated on POD 5 and 7 to 13; lesser increases were noted on POD 14 to 20 and 21 to 27. Ang-2 levels were significantly increased at all time points postop. No significant Ang-1 changes were noted. When compared to preop EC culture results, there was significantly more EC branch point formation, EC invasion, and EC migration assays noted with POD 7 to 13 and POD 14 to 20 plasma.
CONCLUSIONS: MICR is associated with proangiogenic plasma changes for 2 to 4 weeks and plasma from POD 7 to 13 and 14 to 20 stimulated EC growth, invasion, and migration. Postop plasma may stimulate the growth of residual tumor.