title: Prognostic value of matrix metalloproteinase 9 in nasopharyngeal carcinoma: a meta-analysis.
abstract: BACKGROUND
  Recent studies have shown that matrix metalloproteinase 9 (MMP9) plays a vital role in tumor metastasis and is overexpressed in many human cancers. However, the prognostic value of MMP9 overexpression in nasopharyngeal carcinoma (NPC) is conflicting and heterogeneous. We therefore conducted a meta-analysis to investigate the association between MMP9 expression and the prognostic value in NPC.
  
  
  METHODS
  Relevant literature that evaluating the relationship between MMP-9 expression and the outcome of NPC patients were searched in PubMed, Embase, Cochrane, Ovid Medline and Chinese wanfang databases updated to May 2015. The primary study outcome was overall survival (OS). Secondary endpoint was disease-free survival (DFS). The combined hazard ratios (HRs) with their 95% confidence intervals (CIs) were assessed using STATA 12.0 software.
  
  
  RESULTS
  A total of 6 studies were included with the defined including and excluding criteria and subjected to meta-analysis. The pooled result showed that MMP9 overexpression was significantly associated with poor prognosis in terms of OS (HR: 1.65, 95% CI: 1.38-1.95, P<0.0001) and poor DFS (HR: 1.61, 95% CI: 1.28-2.02, P<0.0001) in NPC patients. Subgroup analysis suggested that high expression of MMP9 was associated with poor OS in NPC patients with different sample types. No evidence for publication bias was observed in our meta-analysis.
  
  
  CONCLUSIONS
  The current limited evidence suggests that increased MMP9 expression is associated with poor OS, and DFS in NPC. Therefore, we conclude that overexpression of MMP9 in both NPC tissue and blood sample might serve as an indicator of prognosis in NPC patients.
authors.affiliation: Sino-American Cancer Research Institute, Key Laboratory for Epigenetics of Dongguan City, Key Laboratory for Medical Molecular Diagnostics of Guangdong Province, Guangdong Medical University, Dongguan, China - huangguoliang@gdmc.edu.cn.
authors.forename: Dan
authors.initials: D
authors.lastname: Liao
authors.forename: Haohai
authors.initials: H
authors.lastname: Huang
authors.forename: Zhu
authors.initials: Z
authors.lastname: Zhu
authors.forename: Tong
authors.initials: T
authors.lastname: Li
authors.forename: Huahui
authors.initials: H
authors.lastname: Li
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Huang
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: He
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood*; D002277:Carcinoma; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000097:blood*; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000175:diagnosis* / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D009361:Neoplasm Invasiveness; D011237:Predictive Value of Tests; D011379:Prognosis; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; D020780:Matrix Metalloproteinase 9