Evaluation and Monitoring of Superoxide Dismutase (SOD) Activity and its Clinical Significance in Gastric Cancer: A Systematic Review and Meta-Analysis.

BACKGROUND This systematic review of the literature and meta-analysis aimed to review the evaluation and monitoring of superoxide dismutase (SOD) activity and its clinical significance in gastric cancer. MATERIAL AND METHODS Systematic review involved searching the PubMed, Embase, Ovid, and the China National Knowledge Infrastructure (CNKI) databases. Search terms included 'superoxide dismutase,' and 'gastric cancer.' Studies that included measurements of SOD activity in peripheral blood samples in patients with SOD activity compared with healthy controls. The study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. RESULTS Ten controlled clinical studies were identified that included six studies that measured SOD in serum, three in erythrocytes, and one study that measured SOD on whole blood. Meta-analysis, using the standardized mean difference (SMD) and the 95% confidence interval (CI), showed that patients with gastric cancer had significantly decreased SOD activity when compared with the healthy controls (SMD, -0.840; 95% CI, -1.463 to -0.218; p=0.008). Subgroup analysis was conducted on SOD distribution in the blood (erythrocyte: SMD, -1.773; 95% CI, -2.504 to -1.042; p=0.000) (serum SMD, -0.322; 95% CI, -1.006-0.361; p=0.355) (whole blood: SMD, -1.251; 95% CI, -1.731 to -0.771; p=0.000) and for male subjects (SMD, -2.090; 95% CI, -2.725 to -1.456; p<0.001). CONCLUSIONS Meta-analysis showed that SOD measurements from blood samples, especially in erythrocytes, had potential as a diagnostic and monitoring parameter in patients with gastric cancer.