Background: To clarify the clinical significance of the expression of vascular endothelial growth factor (VEGF) and its receptor, kinase domain-containing receptor (KDR) in colorectal cancer, we evaluated the relationship between the expression of VEGF and KDR, and the microvessel counts and clinicopathological factors in colorectal cancer.
Methods: A total of 259 specimens from sequential colorectal cancer patients who had undergone surgery were examined by the avidin-biotin peroxidase complex method, using anti-human VEGF, anti-human KDR, and anti-human von Willebrand factor antibodies.
Results: The incidence of VEGF expression in the tumor cells of the patients with liver metastasis was significantly higher than that in the tumor cells of the patients without liver metastasis (67% vs 44%). The microvessel count at the tumor invasive edge in the patients whose tumor cells were positive for VEGF was significantly higher than that in the patients whose tumor cells were negative for VEGF (33.0 +/- 7.8 vs 28.0 +/- 7.9); the significant difference in microvessel counts was greater when there was a combination of VEGF and KDR expression. The overall survival rate of patients positive for VEGF was significantly (P = 0.0276) lower than that of those who were negative for VEGF. Although there was no significant difference (P = 0.0743) in the survival rates after potentially curative resection according to VEGF expression, the survival rate of the patients positive for both VEGF in tumor cells and KDR in endothelial cells was significantly (P = 0.0026) lower than that in the patients who were negative for VEGF and/or KDR. In addition, multivariate analysis revealed that the expression of both VEGF and KDR was an independent prognostic factor even after potentially curative resection.
Conclusion: VEGF may be implicated in the definition of the malignant phenotype of colorectal cancer via tumor angiogenesis. VEGF and its receptor KDR expression in tumorous tissues could be useful prognostic factors in colorectal cancer.