Abstract
INTRODUCTION: Matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) are critical components of the extracellular matrix (ECM) in colorectal cancer (CRC). We aimed to evaluate the prognostic value of MMP-2 and MMP-9 in patients with CRC. METHODS: We performed a meta-analysis of cohort studies with available data on the effect of MMP-2 and MMP-9 expression on both disease-free survival (DFS) and overall survival (OS) by the risk ratios (RRs) with their 95% confidence intervals (CIs). Studies were subgrouped based on the different tissue types, including cancer tissue and normal tissue, and the subgroup effect of MMP expression in different tissues was analyzed through meta-regression. To ensure the quality and reduce the risk of bias, the Newcastle‒Ottawa Scale (NOS) was used to assess the included studies. A sensitivity analysis was randomly performed to assess the potential impact of each study on our results. RESULTS: Eighteen trials were selected (Table 1) and included a total of 3944 patients. According to our primary meta-analysis, the expression of MMP-2 was significantly associated with a decrease in OS (RR = 1.75, 95% CI = 1.34 to 2.29, P < 0.001) and DFS (RR = 2.62, 95% CI = 1.25 to 5.49, P < 0.001), and the expression of MMP-9 was not significantly associated with a decrease in OS (RR = 1.48, 95% CI = 0.97 to 2.24, P = 0.069) or DFS (RR = 1.60, 95% CI = 0.87 to 2.94, P = 0.133). According to the subgroup analysis of MMPs in different tissues, high MMP-2 expression in cancer tissue (RR = 1.90, 95% CI = 1.29 to 2.79) and normal tissue (RR = 1.59, 95% CI = 1.17 to 2.17) were significant indicators of poor OS. High MMP-2 expression in cancer tissue was significant indicator of poor DFS (RR = 2.12, 95% CI = 1.09 to 4.11). MMP-9 expression was also associated with poor OS (RR = 1.40, 95% CI = 0.85 to 2.29), but the difference in OS between the high and low expression groups was not statistically significant. CONCLUSIONS: High MMP-2 expression, especially in cancer tissue, is significantly associated with both poor DFS and poor OS in patients with CRC. High MMP-9 expression tended to indicate a poor prognosis of CRC but the correlation was not significant.