Circulating oxidative stress parameters in pre- and post-menopausal healthy women and in women suffering from breast cancer treated or not with neoadjuvant chemotherapy.

We evaluate here the redox status in pre- and post-menopausal healthy women and in women with breast cancer in order to understand the consequences of the hormonal alterations of menopause for the oxidative stress status, its modifications with breast cancer and the influence of neoadjuvant chemotherapy (NC). To that, serum oxidative stress parameters (total antioxidant capacity, lipid peroxidation and protein oxidation), non-enzyme antioxidant defenses (total glutathione, uric acid and bilirubin) and enzyme antioxidant defenses (superoxide dismutase, catalase and glutathione peroxidase activities) were measured in healthy women and in women with breast cancer divided according to their menopausal status and that received or not NC. Circulating estradiol, progesterone, FSH and LH were also analyzed. We found that menopause itself modifies the redox status of healthy women, being most of these differences also reflected in women with breast cancer. However, several changes occur as a consequence of the disease. Furthermore, NC increases oxidative damage, decreases antioxidant defenses and eliminates the differences found in menopause. We conclude that the normal redox balance is disrupted by breast cancer but is also affected by the hormonal status promoted by menopause. In fact, NC nullifies the differences found between pre- and postmenopausal women in several antioxidant defense systems.