Oxidative stress parameters were measured in 59 gastrointestinal cancer patients and 20 controls. 8-hydroxy-deoxyguanosine was quantitated by Elisa method. Superoxide dismutase, catalase, glutathione peroxidase were assayed with colorimetric methods; Nitrite + nitrate, total glutathione and total antioxidant capacity were assayed with spectrophotometric methods.
8-hydroxy-deoxyguanosine levels in cancer patients were higher than those of control group (p < 0.01). Similarly, glutathione levels were increased compared with controls (p < 0.01). However, nitrite + nitrate, total antioxidant capacity levels and superoxide dismutase and catalase activities were decreased in cancer patients compared with controls (p < 0.01, p < 0.01, p < 0.05, p < 0.01, respectively). The patients were divided into two groups; operative (n = 30) and inoperative (n = 29). A significant difference was found in inoperative group compared with postoperative group according to glutathione peroxidase activity (p < 0.05).
Our results demonstrate that the oxidant/antioxidant balance was altered in favor of free radicals and DNA damage in gastrointestinal cancer patients. Significant increases in 8-hydroxy-deoxyguanosine, glutathione and decreases in nitrite + nitrate, SOD, CAT activities and antioxidant molecules suggest the possible involvement of oxidative stress in gastrointestinal cancer. Glutathione peroxidase activities in postoperative patients were higher compared to inoperative patients.