Oxidant-antioxidant status in Indian patients with carcinoma of posterior one-third of tongue

Objective: Cancer of posterior one-third of tongue is seen in 0.43% of total world population. Worldwide, cancer of tongue constitutes 5% of the total cancer incidence. Squamous cell cancer of head and neck is the most common cancer encountered in India. Oxidative stress is potentially harmful to cells and ROS are involved in multistage carcinogenesis, in initiation and promotion. Moreover, the extent of ROS-induced oxidative damage can be exacerbated by decreased efficiency of antioxidant defense mechanisms. The aim of this study was to assess the alterations in the circulating lipid peroxide, antioxidant components and the activities of defense enzymes in patients with cancer of posterior one-third of tongue, with respect to healthy controls in the Indian population. Methods: 60 patients with newly diagnosed, histologically proven cases of locally advanced squamous cell carcinoma (Stage III-IVa) of posterior one-third of tongue were recruited into the study. 60 healthy controls, without history or laboratory evidence of malignancy and inflammatory disorder, were also included in the study, after obtaining informed consent. Single blood samples were taken from patients, before start of therapy and controls. Lipid peroxides, conjugated dienes, reduced glutathione (GSH), vitamin C and E were estimated using standard methods. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) were assayed using commercially available kits from Randox, UK. Results: The pre-treatment levels of plasma lipid peroxide and conjugated dienes were significantly elevated in patients with carcinoma of posterior one-third of tongue, as compared with controls (p = 0.001). Significantly lowered levels of GSH, GPx, SOD and antioxidant vitamins were observed in cancer patients, when compared to control subjects (p = 0.001). Pearson's correlation analysis showed a highly statistitically significant negative correlation between pro-oxidant and anti-oxidant levels in patients. Conclusion: Increased levels of oxidative stress markers and decreased levels of antioxidants in carcinoma of posterior one-third of tongue suggest that oxidative stress markers play a significant role in the pathophysiology of tongue cancer. These findings may suggest possible use of antioxidant supplementation as prophylactic agents for prevention and treatment of tongue cancer. A larger patient cohort for therapeutic response after treatment with a longer follow-up period studies might yield more significant data on their probable use as predictors of chemoradiosensitivity of cancer of tongue.