INTRODUCTION: Angiostatin and endostatin are endogenous inhibitors of 
angiogenesis with anticancer effects. After minimally invasive colorectal 
resection (MICR), blood levels of the proangiogenic factors vascular endothelial 
growth factor (VEGF) and angiopoetin 2 (Ang-2) are elevated for 2-4 weeks. Also, 
postoperative human plasma from weeks 2 and 3 after MICR has been shown to 
stimulate endothelial cell proliferation and migration, which are critical to 
angiogenesis. This proangiogenic state may stimulate tumor growth early after 
MICR. Surgery's impact on angiostatin and endostatin is unknown. This study's 
purpose is to determine perioperative plasma levels of these two proteins in 
colorectal cancer (CRC) patients undergoing MICR.
METHODS: Endostatin levels were assessed in 34 CRC patients and angiostatin 
levels in 30 CRC patients. Blood samples were taken preoperatively and on 
postoperative day (POD) 1 and 3 in all patients; in a subset, samples were taken 
between POD 7 and 20. The late samples were bundled into 7-day blocks (POD 7-13, 
POD 14-20) and considered as single time points. Angiostatin and endostatin 
plasma levels were determined via enzyme-linked immunosorbent assay (ELISA) in 
duplicate. Wilcoxon signed-rank test and Student's t test were used to analyze 
endostatin and angiostatin data, respectively. Significance was set at P<0.0125 
(after Bonferroni correction).
RESULTS: There was a significant decrease in median plasma endostatin levels on 
POD 1, which returned to the preoperative level by POD 3. There was no 
significant difference between pre- and postoperative plasma angiostatin levels.
CONCLUSIONS: MICR has a very transient impact on plasma levels of endostatin and 
no impact on angiostatin during the first 21 days following surgery. Thus, 
angiostatin and endostatin do not likely contribute to or inhibit the persistent 
proangiogenic changes noted after MICR.