title: Clinicopathological and prognostic role of MMP-9 in esophageal squamous cell carcinoma: a meta-analysis.
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.
authors.affiliation: Evidence-Based Medicine Center of Lanzhou University, Lanzhou 730000, China; ; The Second Hospital of Lanzhou University, Lanzhou 730000, China;
authors.forename: Rong
authors.initials: R
authors.lastname: Zeng
authors.affiliation: Evidence-Based Medicine Center of Lanzhou University, Lanzhou 730000, China; ; The Second Hospital of Lanzhou University, Lanzhou 730000, China;
authors.forename: Lei
authors.initials: L
authors.lastname: Duan
authors.affiliation: The Second Hospital of Lanzhou University, Lanzhou 730000, China;
authors.forename: Yuke
authors.initials: Y
authors.lastname: Kong
authors.affiliation: The First Hospital of Lanzhou University, Lanzhou 730000, China;
authors.forename: Yaojun
authors.initials: Y
authors.lastname: Liang
authors.affiliation: The Second Hospital of Lanzhou University, Lanzhou 730000, China;
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Wu
authors.affiliation: Linxia Hospital, Linxia 731100, China.
authors.forename: Xuequan
authors.initials: X
authors.lastname: Wei
authors.affiliation: Evidence-Based Medicine Center of Lanzhou University, Lanzhou 730000, China;
authors.forename: Kehu
authors.initials: K
authors.lastname: Yang
keywords: Matrix metalloproteinase-9 (MMP-9); esophageal squamous cell carcinoma (ESCC); meta-analysis; overall survival (OS)