[Free radical reactions and cancer]

Activities of superoxide dismutase (SOD) and catalase as well as content of malonyl dialdehyde (MDA) were estimated in the blood of patients with tumor of gastrointestinal tract. In the early stage of development of tumor SOD activity and concentration of MDA in whole blood was decreased while catalase activity was increased significantly. In the cases of metastases spreading and cachexia both SOD and catalase activities were greatly decreased; the content of MDA was increased.