Fatigue is common in cancer patients receiving adjuvant chemotherapy. To further understand the mechanism of fatigue and search for potential biomarkers, we will conduct a prospective study with breast cancer patients receiving adjuvant chemotherapy.

Patients with breast cancer undergoing adjuvant systemic chemotherapy based on the use of anthracyclines will be screened before the start of chemotherapy.

Patients whose scores on the brief fatigue inventory (BFI) increase after having received the first cycle of chemotherapy will be considered as having manifested fatigue. The patients whose fatigue won't worse following the first cycle of chemotherapy will be used as controls. We will collect blood samples of both groups before and 21 days after the start of chemotherapy. We will analyze the following biomarkers: IL2, IL10, TNF and TGFB-1 measured by amplification reaction; FSH, LH, estradiol, DHEA, DHEAS and cortisol hormones measured by chemiluminescent enzyme immunometric assay

Inclusion Criteria:

• Non metastatic breast cancer;
• Patients undergoing adjuvant chemotherapy

Exclusion Criteria:

• hypothyroidism;
• Depression;
• anemia;
• heart disease or decompensated hypertension

Patients with stage I, II and III breast cancer undergoing adjuvant systemic chemotherapy based on the use of anthracyclines will be screened before the start of their treatment.