Evaluation of Thyroid Abnormity Incidence and Thyroid Toxicity During Chemotherapy Among Newly Diagnosed Breast Cancer

Inclusion Criteria: 1. Female patients with histologically or cytologically proven primary breast cancer; 2. Age \>18 years; 3. ECOG Performance Status: 0-2; 4. Life Expectancy: 3 months or more; 5. No previous anti-cancer therapy; 6. Be willing to undergo at least four cycles of anthracycline or taxane-based chemotherapy; 7. Adequate hematological, liver, and kidney functions. Exclusion Criteria: 1. Pregnancy or lactation; 2. History of other malignancy or secondary breast cancer; 3. History of thyroid disease; 4. History of drug addiction or abuse; 5. History of immunodeficiency disease; 6. Treatment with drugs capable of influencing thyroid gland functions within 3 months prior to study entry; 7. Nonmeasurable disease such as un-controlled diabetes, severe cardiovascular and cerebrovascular diseases; 8. Current, recent (within 4 weeks prior to study entry), or planned participation in any other clinical trials; 9. Inability to understand and agree to informed consent.