ANTIOXIDANT ENZYME-ACTIVITIES AND OXIDATIVE STRESS IN HUMAN BREAST-CANCER

We have analysed products of lipid peroxidation reactions and activiti es of antioxidant enzymes in cancerous breast tissue and in correspond ing reference tissue. In addition, the serum lipid peroxidation and pe roxyl-radical-trapping capacity of breast cancer patients were compare d to those of healthy subjects. A total of 23 patients with breast can cer participated in this study. In the cancerous tissue, catalase acti vity was lower than in the reference tissue, while the activities of s uperoxide dismutase, glutathione peroxidase and the hexose monophospha te shunt were elevated. The content of thiobarbituric-acid-reactive ma terial was slightly lower in the cancerous tissues, but the levels in serum were found to be elevated in patients with breast cancer. The am ounts of conjugated diene double bonds were essentially equal both in the cancerous and in the reference tissue. Moreover, in breast cancer patients the serum levels of diene conjugation and the peroxyl-radical -scavenging capacity did not differ from those measured in healthy sub jects. This study indicates that the antioxidant defence system is alt ered in cancerous breast tissues, but does not support the hypothesis suggesting that formation of lipid peroxides in the tumour tissue itse lf is of primary importance in the carcinogenesis.