Matrix metalloproteinase 9 expression and prognosis in colorectal cancer: a meta-analysis

Matrix metalloproteinase-9 (MMP-9) is an important member of the matrix metalloproteinase family and is considered to be involved in the invasion and metastasis of cancer cells. Many studies were published to assess the prognostic role of MMP-9 overexpression in patients with colorectal cancer, but the findings from those studies were inconsistent. We searched eligible studies in Pubmed, Embase, and Web of Science databases. Thirteen studies with a total of 2, 390 CRC patients were finally included into the meta-analysis. The pooled hazard ratios (HRs) with the corresponding 95 % confidence interval (95 % CIs) for overall and progression-free survival were calculated by using meta-analysis. There were nine studies with a total of 1,674 colorectal cancer patients relating the progression-free survival, and eight studies with a total of 1,379 colorectal cancer patients relating the overall survival. Overall, MMP-9 overexpression was associated with poorer progression-free survival in patients with colorectal cancer (fixed-effects HR 1.81, 95 % CI 1.48-2.20, P < 0.001; random-effects HR 1.92, 95 % CI 1.46-2.53, P < 0.001). In addition, MMP-9 overexpression was also associated with poorer overall survival in patients with colorectal cancer (fixed-effects HR 1.74, 95 % CI 1.39-2.19, P < 0.001; random-effects HR 1.78, 95 % CI 1.31-2.41, P < 0.001). MMP-9 expression is associated with the prognosis of patients with colorectal cancer, and patients with higher MMP-9 expression have poorer survival.