Abstract
Background and Objectives: Cancer of posterior one‐third of tongue is seen in 0.43% of total world population. Squamous cell carcinoma 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 correlation of therapeutic response on chemoradiation with the change in oxidant‐antioxidant profile has not been studied till date. The aim of this study was to study 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 and to monitor the variations in their levels before and after chemoradiation and to assess the relevance of these levels to therapeutic response.
Methods: Sixty newly diagnosed patients with cancer of posterior one‐third of tongue (Stage III–IVa) and 60 healthy controls were enrolled in this study. The samples were collected: before the start of therapy; after the second course of chemotherapy; two weeks after the completion of teleradiation and after 1 year on follow‐up. Single blood samples were taken from controls. Lipid peroxides, conjugated dienes, reduced glutathione (GSH), catalase (CAT) and glutathione‐S‐transferase (GST) were estimated using standard methods. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) were assayed using commercially available kits from Randox, UK. Response to therapy was assessed during and after therapy and after one year of follow‐up.
Results: The pre‐treatment levels of plasma lipid peroxide were significantly elevated whilst significantly lowered levels of GSH, GPx, GST, SOD and CAT were observed in cancer patients, when compared to controls. After chemotherapy, the levels of lipid peroxidation showed a significant decline in complete responders, as compared with partial/non‐responders; which became highly significant after completion of therapy. This fall remained significant after one year of completion of therapy during follow‐up. The levels of GSH, GPx, SOD and CAT showed a mild increase (p<0.05), after chemotherapy in complete responders, as compared with partial/non‐responders; which became highly significant after completion of therapy.
Conclusion: This important finding suggests that pre‐treatment levels of antioxidant‐oxidant parameters and the extent of their change during treatment can predict the therapeutic response to chemoradiation in patients with cancer of posterior one‐third of tongue A larger patient cohort with a longer follow‐up period for therapeutic response studies might yield more significant data on their probable use as predictors of chemoradiosensitivity of advanced tongue cancer.
Citation Information: Cancer Prev Res 2010;3(1 Suppl):A43.
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