Background: Minimally invasive colorectal resection (MICR) is associated with persistently elevated plasma VEGF levels that may stimulate angiogenesis in residual tumor foci. Placenta growth factor (PlGF) stimulates neovascularization in tumors by modulating VEGF's effects. This study's purpose was to determine the impact of MICR on blood PlGF levels in cancer patients (Study A) and to compare PreOp levels in patients with cancer and benign (BEN) disease (Study B).
Methods: Blood samples were collected preoperatively, on postoperative day (POD) 1, POD 3, and at various time points 2-4 weeks after surgery. Samples from 7-day periods after POD 6 were bundled to allow analysis. Plasma PlGF levels were determined via ELISA, results reported as mean±SD, and data analyzed via t test. Significance was set at p<0.008 after Bonferroni correction.
Results: Study A: 76 colorectal cancer (CRC) patients had MICR (laparoscopic, 59%; hand-assisted, 41%). The mean length of stay was 5.8±2.1 days. The mean PreOp PlGF level was 15.4±4.3 pg/ml. Significantly increased levels were noted on POD 1 (25.8±7.7 pg/ml, p<0.001), POD 3 (22.9±6.7, p<0.001), POD 7-13 (19.2±5.1, p<0.001), and POD 14-20 (19.5±6.7, p<0.002). The mean POD 21-27 level was not significantly different from baseline. Study B included 126 CRC and 111 BEN patients. PreOp levels were higher in the CRC patients (15.6±5.3 pg/ml) than in the BEN group (13.5±5.5 pg/ml, p=0.001).
Conclusions: PlGF levels are elevated for 3 weeks after MICR and PreOp plasma levels are higher in CRC patients than in BEN disease patients. The cause of the postoperative increase is unclear. The persistently higher blood levels of PlGF and VEGF after MICR may stimulate angiogenesis in residual tumor foci. Further studies regarding late blood protein alterations after surgery appear to be indicated.