Antioxidant status in breast cancer patients of different ages after radiotherapy

In this study we investigated the effects of breast cancer radiotherapy on the antioxidant (AO) enzyme activities of copper, zinc superoxide dismutase (CuZnSOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR), as well as on the concentration of reduced glutathione (GSH) and lipid peroxides (LP) in blood of patients aged 45-58 years and older than 60 years. The results show that in blood of patients aged 45-58 years, radiotherapy increased the activities of CuZnSOD, CAT, and GR, as well as the concentration of GSH, without affecting the activity of GPx and concentration of LP. In patients older than 60 years, radiotherapy increased the activities of CuZnSOD and CAT, lowered the activity of GPx and concentration of GSH, and increased the concentration of LP. Our results indicate that the response to radiotherapy involves age-related impairment of AO capacity for elimination of H2O2, causing oxidative damage to blood cells. This suggests that cytotoxic effects of radiation on healthy tissues might be more pronounced during the aging of breast cancer patients, and should be considered in the further development of individualization protocols in cancer radiotherapy