Lipid peroxidation, free radical production and antioxidant status in breast cancer

Reactive oxygen metabolites (ROMs), including superoxide anion (O-2(.-)), h ydrogen peroxide (H2O2) and hydroxyl radical ((OH)-O-.), play an important role in carcinogenesis. There are some primary antioxidants such as superox ide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) which protect against cellular and molecular damage caused by the ROMs. We conduc ted the present study to determine the rate of O-2(.-) and H2O2 production, and concentration of malondialdehyde (MDA), as an index of lipid peroxidat ion, along with the SOD, GPx and CAT activities in 54 breast cancer (BC) pa tients. Forty-two age- and sex-matched patients with minor surgical problem s, who had no history of any neoplastic or breast disorders, were taken as controls. The rate of O-2(.-) production was significantly higher (p < 0.001) in BC p atients than controls, irrespective of clinical stages and menopausal statu s. Similarly, H2O2 production was significantly higher in BC patients, espe cially in stage III and postmenopausal groups, as compared to the respectiv e controls. MDA concentration was also observed significantly elevated in s tage II (p < 0.001), stage III (p < 0.01), postmenopausal (p < 0.005), and premenopausal (p < 0.02) group as compared to their corresponding controls. SOD and GPx activities were found significantly raised in all the groups ( p < 0.001), except the GPx activity was found a smaller alteration in stage IV (p < 0.02). On the contrary, CAT activity was found significantly depre ssed in all the study groups. The maximum depression was observed in stage II (-61.8%). Lower CAT activity in our study may be the effect of higher pr oduction of ROMs, particularly O-2(.-) and (OH)-O-.. SOD and GPx, however, were less effected by these higher ROMs production. The results of our stud y have shown a higher ROMs production and decreased CAT activity, which sup port the oxidative stress hypothesis in carcinogenesis. The relatively high er SOD and GPx may be due to the response of increased ROMs production in t he blood. However, the higher SOD and GPx activities may be inadequate to d etoxify high levels of H2O2 into H2O leading to the formation of the most d angerous (OH)-O-. radical followed by MDA. Therefore, administration of CAT may be helpful in the management of BC patients. However, further elaborat e clinical studies are required to evaluate the role of such antioxidant en zymes in BC management.