\ A Case control study to evaluate oxidative stress in plasma samples of oral malignancy

Background: Imbalances between the oxidant - antioxidant status have been implicated in the pathogenesis of several diseases, including cancer. Aim: The aim of this study was to evaluate the extent of lipid peroxidation and antioxidants in the venous blood samples of oral squamous cell carcinoma patients of different Clinicopathologic stages in comparison with the healthy controls. Setting and Design: A Case control study was designed in a hospital (Rajah Muthiah Dental College and Hospital, Annamalai University) based setting. Materials and Methods: Twenty new histopathologically proven oral carcinoma patients, and equal number of age, sex and habit matched healthy subjects were recruited for this study. Their blood samples were subjected to evaluation of Thiobarbituric Acid Reactive Substances (TBARS) and antioxidant enzymes, namely, superoxide dismutase (SOD), Catalase (CAT) reduced glutathione (GSH) and glutathione peroxidase (GPx) using spectrophotometric methods. Statistical Analysis: The data are expressed as mean +/- SD. The statistical comparisons were performed by independent Student's t-test and One Way ANOVA. P value <0.05 was considered statistically significant. Karl Pearson correlation was performed for the biochemical parameters within the group and between the groups. For statistically significant correlations, linear regression was performed. Results: Significant enhanced lipid peroxidation (P<0.001) with decrease in antioxidants (P<0.001) was observed in the venous blood of oral squamous cell carcinoma patients as compared with the healthy controls. Accordingly, significant (P<0.001) pattern of progression in TBARS levels was observed at various clinical stages of patients. (GSH) showed significant (P<0.01) negative correlation with TBARS and positive correlation (P<0.001) with SOD. On linear regression analysis, GSH showed significance for SOD (P<0.001), GPx, CAT and TBARS (P<0.01). It was also found that, 70% of variance in SOD can be attributed to the influence of GSH alone. Conclusion: Enhanced lipid peroxidation and compromised antioxidant defense in plasma indicate development of oxidative stress. Amongst the antioxidant enzymes, (GSH) appears to have a profound role in carcinogenesis.