Abstract
OBJECTIVE: Many studies reported that matrix metalloproteinase-9 (MMP-9) participated in the development of esophageal squamous cell carcinoma (ESCC) and resulted in poor prognosis, however, they all included few patients and had inconsistent results. So we conducted a meta-analysis to explore the correlation between overexpression of MMP-9 and the clinicopathological characteristics and overall survival (OS) of ESCC. METHODS: PubMed, EMBASE, Web of Science, Chinese Biomedical Literature Database, Google Scholar and other databases were searched for relevant studies. The Newcastle-Ottawa quality assessment scale was used to assess the methodological quality of included study and RevMan 5.2 software was used to conduct meta-analysis. RESULTS: A total of 35 studies were included, and the results of meta-analysis showed that overexpression of MMP-9 was associated with grade of differentiation [well/moderate vs. poor: odds ratio (OR): 0.39, 95% confidence interval (CI): 0.29-0.52; P<0.00001], lymph node metastasis (negative vs. positive: OR: 0.24, 95% CI: 0.16-0.34; P<0.00001), TNM stage (T1/T2 vs. T3/T4: OR: 0.28, 95% CI: 0.14-0.54; P=0.0002), the depth of invasion (T1/T2 vs. T3/T4: OR: 0.29, 95% CI: 0.17-0.49; P<0.00001), and vascular invasion of ESCC (negative vs. positive: OR: 0.35, 95% CI: 0.21-0.58; P<0.0001), and also associated with poor overall survival of ESCC (HR: 2.17, 95% CI: 1.32-3.57; P=0.002). Subgroup analysis showed that more than 10% of carcinoma cell staining was associated with significant increase of mortality risk (HR: 2.44, 95% CI: 1.16-5.15; P=0.02), and sensitive analysis suggested that MMP-9 was an independent prognostic factor in ESCC (HR: 1.49, 95% CI: 1.16-1.91; P=0.002). CONCLUSIONS: On the basis of limited evidence, overexpression of MMP-9 may be a potential independent prognosis factor of ESCC patients in Asia, and high-quality studies assessing the prognostic significance of MMP-9 for ESCC patients are still needed.