Estimation of serum and salivary matrix metalloproteinase levels in oral squamous cell carcinoma patients: a systematic review and meta-analysis

Introduction
Matrix metalloproteinases (MMPs) play a pivotal role in the cancer progression, invasion, and angiogenesis. Aim: This meta-analysis was conducted to evaluate the difference between oral squamous cell carcinoma (OSCC) patients and healthy controls in the serum and salivary MMP levels.

Material and methods
Four databases – Web of Science, PubMed, Scopus, and Cochrane Library – were searched up to March 2019. The pooled standard mean difference (SMD) and 95% confidence interval (CI) were obtained to explain the difference between the patients and controls in the salivary and serum MMP levels. Both Egger’s and Begg’s tests were considered as the significant publication bias.

Results
Thirteen case-control studies were included in the meta-analysis. Among the analyses of serum MMP levels, the serum MMP7 (SMD = 0.78; 95% CI: 0.15–1.41; p = 0.02) and MMP9 (SMD = 1.18; 95% CI: 0.51–1.84; p = 0.0005) levels were significantly higher in the OSCC patients than in the controls. In addition, the analyses of salivary MMP levels showed that the MMP1 (SMD = 0.46; 95% CI: 0.22–0.70; p = 0.0001) and MMP9 (SMD = 0.66; 95% CI: 0.19–1.12; p = 0.005) levels were significantly higher in the OSCC patients than in the controls.

Conclusions
The meta-analysis showed that the serum MMP7 and MPP9 levels as well as the salivary MMP1 and MPP9 levels were significantly higher in the OSCC patients than in the controls.