Expression of thrombospondin-1 inversely correlated with tumor vascularityand hematogenous metastasis in colon cancer

Solid tumors require neovascularization for growth and metastasis. Angiogen esis depends on the local balance between various molecules that induce and inhibit neovascularization. Thrombospondin-1 (TSP-1) is thought to be an a ntiangiogenic factor. In this study, we examined the correlation between ex pression of TSP-1 and tumor vascularity, and determined its prognostic sign ificance in colon cancer. Microvessel density, determined by immunostaining for factor VIII-related antigen, was significantly higher in tumors that w ere TSP-1-negative. TSP-1 expression was inversely correlated with prognosi s. Patients with TSP-1-negative tumors had a significantly worse prognosis than did those with TSP-1-positive tumors, Frequency of hepatic recurrence was significantly higher in patients with tumors that were TSP-1-negative. In conclusion, TSP-1 is an important negative regulator of tumor angiogenes is, and TSP-1 may be useful for predicting recurrence in patients with colo n cancer.