Immunohistochemical expression of vascular endothelial growth factor and microvessel counting as prognostic indicators in node-negative colorectal cancer

This manuscript reports a carefully controlled study of patients with Dukes B colorectal cancer ( Dukes stage A, n = 12 and Dukes stage B, n = 44). Immunohistochemistry has been used to demonstrate reactivity for vascular endothelial growth factor ( VEGF), and to measure levels of microvessel density (MVD) in order to assess the relationship of tumor angiogenesis with clinical outcome. Immunohistochemistry was performed using antibodies to VEGF and CD34 ( for intratumoral vessel identification) and counting was performed at the invasive margin of the tumor. Results showed that for Dukes stage A patients 4/12 died of their disease, none of whose tumor was VEGF positive. In contrast, 2 patients who survived were positive for VEGF cytoplasmically, but neither showed increased tumor MVD. In Dukes B patients 10/44 died, 5 of whose tumor demonstrated VEGF reactivity, both in malignant cells and in tumor vascular endothelium. MVD ranged from 11 to 53 ( median 28) for Dukes A cases and from 9 to 69 ( median 32.5) for the Dukes B group. Kaplan-Meier plots and log rank test statistics for Dukes B patients demonstrated that VEGF reactivity in cells, and in tumor vascular endothelium was correlated with survival ( p = 0.047 and p <= 0.06, respectively). There was a significant relationship between the presence of VEGF reactivity on vascular endothelium and outcome by Fisher's exact test ( p = 0.018). Similarly, by the same test VEGF positivity was significantly correlated with patient mortality ( p = 0.032). The presence of endothelial VEGF reactivity correlated with VEGF in malignant cells ( p = 0.0001) by Mann-Whitney U test and a significant inverse relationship between vessel density and patient survival was demonstrated ( p = 0.019). The finding that in Dukes B patients MVD was inversely correlated with mortality supports the hypothesis that a low microvascular count is predicted close to the invasive margin, where VEGF expression is upregulated in response to hypoxia, induced by a lack of a functional vasculature. These data will be used to identify cohorts of patients who have a high risk of relapse and can be selected for adjuvant therapies such as VEGF antibody or antitumor antibody-directed therapy. Copyright (C) 2005 S. Karger AG, Basel.