Oxidant/Antioxidant Status of Breast Cancer Patients in Pre- and Post-Operative Periods.

The purpose of this study is to evaluate the level of oxidative stress before and after breast cancer surgery. Malondialdehyde (MDA) level was tested using a thiobarbituric acid (TBA) assay based on the release of a color complex due to TBA reaction with MDA. The glutathione S-transferase (GST) activity was evaluated by enzymatic conjugation of reduced glutathione (GSH) with 1-chloro-2,4-dinitrobenzene. The level of total glutathione (reduced GSH and oxidized GSSG) was detected using a recycling system by 5,5-dithiobis(2-nitrobenzoic acid). The levels of the indices were determined in the serum of 52 patients before surgery, two hours and five days after surgery, and in 42 healthy women. In the patients over 50 years old the level of MDA was higher after surgery in comparison with before surgery, and GST activity was lower in comparison with the control. The GSH + GSSG level in both ages groups after surgery was lower than in the control. Significant differences of MDA level were detected in patients with stage III after surgery compared to the control. The level of GSH + GSSG was significantly lower in the patients with I-III stages compared to the control. The most expressed changes demonstrate the significance of MDA as a marker to evaluate oxidative stress in breast cancer patients. The degree of oxidative stress depends on the patient's age and stage of disease.