Expression and prognostic significance of angiopoietin in colorectal carcinoma

BACKGROUND AND OBJECTIVES: Growth and metastasis of malignant tumors depend on the angiogenesis. The aim of this study was to elucidate the prognostic significance of angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) expression in advanced colorectal carcinoma. METHODS: Totally, 101 patients with surgically resected advanced colorectal carcinomas were enrolled. The tumor expressions of Ang-1 and Ang-2 were evaluated immunohistochemically, and their relationships with clinicopathological factors and prognosis were investigated. Tumor microvessel density (MVD) was also calculated and correlated with angiopoietin expression. RESULTS: Ang-1 and Ang-2 were detected in 26 (25.7%) and 45 (44.6%), respectively, of 101 cancerous lesions. Overexpression of Ang-1 was correlated with high MVD. Overexpression of Ang-2 was correlated with lymph node metastasis, venous invasion, preoperative carcinoembryonic antigen levels, and high MVD (P < or = 0.05). MVD was not significantly upregulated by Ang-1 expression, but was significantly upregulated by Ang-2 expression (P < or = 0.01). However, only patients with Ang-2 overexpression showed a significantly worse prognosis than those without Ang-2 overexpression. Multivariate analysis with logistic regression for 5-year survival revealed that cancerous stage and Ang-2 overexpression were independent prognostic indicators. CONCLUSIONS: The Ang-1 expression correlated with MVD. However, Ang-2 expression was a useful prognostic marker in the management of patients with advanced colorectal carcinoma.