Hypomagnesemia and Its Relationship with Oxidative Stress Markers in Women with Breast Cancer.

Reduced serum magnesium concentrations in women with breast cancer compromises one of the antioxidant defense system involved in the carcinogenesis process. To evaluate parameters of magnesium, the enzyme activity of superoxide dismutase, and its relation with oxidative stress markers in women with breast cancer. A case-control study was conducted, involving 60 women in the age range between 29 and 65 years, divided into two groups: women with breast cancer (n = 30) and women without breast cancer (n = 30). Plasma; ionized, erythrocytic, and urinary magnesium intake; plasma concentrations of thiobarbituric acid reactive substances; and erythrocyte superoxide dismutase enzyme activity were evaluated. The mean value of the amount of dietary magnesium was below the recommended level in both groups studied, with no statistical difference (p > 0.05). Plasma, ionized, and erythrocyte magnesium concentrations of women with breast cancer were reduced in relation to the control group (p < 0.0001) and inadequate according to the reference values. Urinary excretion was high, with a significant difference between groups (p < 0.0001). The mean concentration of thiobarbituric acid reactive substances was high in the study participants, with no significant statistical difference between the groups (p > 0.05). The mean values of superoxide dismutase enzyme activity were adequate, with no statistically significant difference between the groups (p > 0.05). Women with breast cancer have impaired magnesium homeostasis, characterized by its reduction in diet, plasma, and erythrocytes and its increase in urine.