Matrix metalloproteinase-9 is associated with relapse and prognosis of patients with colorectal cancer

Background: Matrix metalloproteinase-9 is a member of the MMP family, which is overexpressed in some solid tumors and is thought to enhance tumor invasion and metastasis ability. The present study aims to examine MMP-9 expression in human colorectal cancer and to determine its association with clinicopathological characteristics and prognosis. Methods: Colorectal cancer and adjacent normal tissues from 192 patients were investigated by immunohistochemical assay. Staining evaluation results were analyzed statistically in relation to various clinicopathological characters, disease-free survival, and overall survival. Results: High level of MMP-9 expression was detected in colorectal cancer, significantly more than in normal colorectal epithelial cells. In colorectal cancer, MMP-9 was significantly positively correlated with depth of invasion, lymph node metastasis, and distant metastasis. However, no correlations between MMP-9 expression and patient age, sex, tumor location or differentiation status were detected. Disease-free and overall survival were significantly poorer for patients with positive MMP-9 staining than for those with MMP-9-negative tumors. Conclusions: Our findings emphasize the important role of MMP-9 in the invasion and metastasis process in human colorectal cancer. It could also serve as a novel prognostic marker that is independent of, and additive to, the tumor-node-metastasis (TNM) staging system.