Study of the vascular endothelial growth factor (VEGF) expression and microvascular density (MVD) in primary...

Determine the relationship between vascular endothelial growth factor (VEGF) expression and microvascular density (MVD) in primary colorectal cancer specimens including the prognostic value by evaluating the correlation between various common reported prognostic histopathologic indictors and these two angiogenic parameters. The Inter-observer reliability on VEGF and MVD measurement was also determined.

Anti-VEGF and anti-factor CD34 monoclonal antibodies immunohistochemical staining was performed in 40 randomly selected formalin-fixed paraffin-embedded colorectal cancer specimens of non-stage-IV patients who underwent curative resection using. Immunoreactive in 25% or more carcinoma cells was categorized as positive. The intensity of VEGF expression was graded in a semiquantitative fashion, ranging from 0 to 2 Tumor MVD was determined by counting any endothelial cells stained with CD34 per two randomly selected fields at x200 magnification in each slide. The correlation between VEGF expression and MVD was evaluated. Inter-observer agreement was assessed by comparing the results of VEGF and MVD measurements made by two pathologists.

A moderate correlation was found between the percentage of positive immunoreactive cells and the intensity of VEGF immunoreactive staining (correlation value of 0.436, p < 0.05). MVD was found having no correlation with both the percentage of positive immunoreactive cells and intensity of VEGF immunoreactive staining (the correlation value of -0.056, p = 0.732 and 0.108, p = 0.506, respectively). Neither MVD nor VEGF expression in primary colorectal cancer tissue was found having a significant correlation with any common reported prognostic histopathologic indictors. In counting CD34-stained endothelial cells, this study revealed a high intra-observer correlation coefficient of 0.886 (95% CI: 0.715-0.955) for the first pathologist and 0.913 (95% CI: 0.782-0.965) for the second. High inter-observer reliability was found in both MVD and VEGF measurement with a substantial agreement (agreement: 95%, kappa = 0.643) between the two pathologists.

In primary colorectal cancer tissues, there was no significant relationship between MVD and VEGF expression. This study revealed a high intra and inter-observer reliability on VEGF and MVD measurement. Neither MVD nor VEGF expression provided predictive value of advanced or aggressiveness of disease. Further studies on larger sample size would help validate these results.