Investigate the protective effect of chronic MitoQ supplementation on cardiovascular toxicity induced by doxorubicin-based adjuvant chemotherapy in breast cancer patients.

Test the hypothesis that chronic MitoQ supplementation in breast cancer patients treated with doxorubicin prevents:

1. increased mitochondrial oxidative stress;
2. the increase in cardiac markers (B-type natriuretic peptide and troponin I);
3. changes in left ventricular deformity (speckle tracking, strain) and reduction in LVEF;
4. endothelium-dependent dysfunction of peripheral vascular beds;
5. the increase in endothelial microvesicles;
6. the increase in material stiffness;
7. the elevation of central blood pressure.

Inclusion Criteria:

• Patients ≥18 years old, diagnosed with breast cancer (ductal, lobular and mixed carcinoma), in stage 1-3, with indication for the adjuvant AC-T therapeutic scheme, doxorubicin (60 mg/m2) plus cyclophosphamide, will be considered eligible for the study (600 mg/m2) in the regimen of 1 cycle every 21 days, followed by weekly taxane for 12 cycles.

Exclusion Criteria:

• Patients with metastasis, severe lymphedema, renal failure, acute myocardial infarction, heart failure, stroke and chronic liver disease.