[Biochemical mechanisms of acquired radioresistance of tumor tissue].

The level of lipoperoxidation products in radioresistant tumour is 3 times lower and superoxide dismutase activity--3.5 times higher than in the intact tumour. That is an evidence of high stability. The level of lipoperoxidation products in the brain and liver of rats with radioresistant variant of Guerin carcinoma is essentially less and catalase activity--considerably higher, than in the rats with intact tumour. This evidences for the corresponding increase of antioxidant protection of the organisms in the process of acquiring the tumour radioresistance.