Matrix metalloproteinase-9 as a prognostic factor in gastric cancer: a meta-analysis

Background: Matrix metalloproteinase-9 (MMP-9) is associated with disruption of basement membranesof blood vessels and promotion of metastasis through the lymphatics. However, its prognostic value for survivalin patients with gastric cancer remains controversial. Method: We therefore conducted a meta-analysis of thepublished literature in order to clarify the impact of MMP-9. Clinical studies were selected for further analysisif they provided an independent assessment of MMP-9 in gastric cancer and reported analysis of survival dataaccording to MMP-9 expression. Results: A total of 11 studies, covering 1700 patients, were included for metaanalysis.A summary hazard ratio (HR) of all studies and sub-group hazard ratios were calculated. The combinedHR suggested that a positive MMP-9 expression had an impact on overall survival: 1.25 (95% confidence interval1.11-1.40) in all eligible studies; 1.13 (1.06-1.20) in 8 studies detecting MMP-9 by immunohistochemistry; 1.36(1.12-1.65) in 7 studies from Asia. Only one study for DFS showed a significant impact on disease free survival(HR 1.73, 95%CI 1.27-2.34). Conclusions: Our findings suggested that MMP-9 protein expression might be afactor for a poor prognosis in patients with gastric cancer. However, the association was rather weak, so that moreprospective studies should further explore the prognostic impact of MMP-9 mRNA and correlations betweenMMP-9 and clinicopathological characteristics.