Oxidative Stress Parameters in Patients with Breast Cancer before and after Radiotherapy

Abstract

REACTIVE oxygen species (ROS) are generated in response to endogenous or exogenous stimuli. Antioxidants defense system resists for balancing ROS-mediated injury; if oxidation exceeds the defense mechanisms, oxidative stress is generated. Oxidative stress may be involved in the development of breast cancer. Moreover, radiationtherapy (RT), used for the treatment of breast cancer, works by the production of reactive oxygen species at the site of radiation which leads to local oxidative stress. Studies which detect one or few oxidant and antioxidant markers failed to detect the overall oxidant/antioxidant status of the subjects. The authors aim at studying the impact of radiotherapy on the total oxidant status (TOS), total antioxidant status (TAS) with calculation of oxidative stress index (OSI), and measure the lipid peroxidation (MDA) in breast cancer patients.TAS, TOS, MDA and OSI in healthy and breast cancer groups are measured. In breast cancer group, all parameters were measuredbefore and after radiation therapy.In the breast cancer group, TOS, OSI and MDA levels have increased significantly (P<0.001) and the TAS level has decreased (P<0.001) in the breast cancer patients after radiotherapy than before radiotherapy. Breast cancer group TAS after RT reaches about forth its level measured inthe control group. Radiotherapy in breast cancer patients depletes the total antioxidants (TAS), increases total oxidative status (TOS), lipid peroxidation (MDA) and OSI. Breast cancer and its treatment modalities display the patients in a state of severe oxidative stress which requires the supplementation of antioxidants.