Oxidant and antioxidant activity changes in patients with oral cancer and treated with radiotherapy.

Of all the clinical disciplines, radiotherapy probably has the most secure and scientific foundations. In oral cancer, radiotherapy may be used as the sole treatment or in combination with other modalities of treatment. Blood samples were collected from stage III oral cancer patients attending the Oncology Department, Bernard Institute of Radiation and Oncology, Chennai Medical College, Chennai, India, before initiating radiotherapy and after the sixth week of radiotherapy. The effect of radiation on oral cancer patients has been studied using activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPX), glutathione reductase (GR), glutathione-S-transferase (GST), glucose-6-phosphate dehydrogenase (G6PDH) and levels of malondialdehyde (MDA). The levels of MDA showed a significant increase in untreated and radiation oral cancer patients when compared with normal subjects. The activities of red blood cell (RBC) hemolysate antioxidant enzymes such as SOD, catalase, GPX, GR, GST and G6PDH showed a significant decrease, representing the lack of antioxidant defense. Radiation induces lipid peroxidation by inactivating the antioxidant enzymes, thereby rendering the system inefficient in management of the free radical attack. Thus, the degree of radiation affects the extent of the depression of the antioxidant enzyme activities and increases lipid peroxidation.