BACKGROUND: Solid tumors are angiogenesis dependent, and elevated levels of 
proangiogenic cytokines have been reported in a variety of histologies. 
Endostatin is an antiangiogenic fragment of the basement membrane protein, 
collagen XVIII. Because antiangiogenic protein fragments may be generated by 
tumor-derived proteases, the authors sought to determine whether circulating 
levels of endostatin were elevated in patients with localized soft tissue 
sarcoma.
METHODS: The authors analyzed preoperative serum levels of endostatin, vascular 
endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) in 
25 patients (14 males and 11 females; mean age, 44 years) with soft tissue 
sarcoma. For each serum sample, two aliquots were assayed in duplicate using a 
competitive enzyme immunoassay. Serum levels were compared with levels from 34 
age-matched and gender-matched volunteer blood donors.
RESULTS: Endostatin levels were significantly higher in sera from sarcoma 
patients than in sera from healthy controls (43.0 ng/mL vs. 25.8 ng/mL, 
respectively; P = 0.0002; Mann-Whitney U test). Significant elevations also were 
noted in VEGF and bFGF levels (P = 0.0002 and P = 0.0001, respectively). 
Furthermore, endostatin levels > 2 standard deviations above the control mean 
(55 ng/mL) were associated with an increased risk of tumor recurrence after 
resection (P = 0.047; log-rank test).
CONCLUSIONS: Serum endostatin, VEGF, and bFGF levels are elevated in patients 
with soft tissue sarcoma. Elevated endostatin levels appear to be associated 
with tumor aggressiveness. The role of these cytokines in sarcoma angiogenesis 
and as potential targets for therapy warrants further study.