Inter-ethnic differences in tolerance of anti-cancer drugs in breast cancer patients

This study is looking at whether Asian and Caucasian women with breast cancer respond differently to chemotherapy drugs. Some research suggests that Asian women may experience more side effects from certain cancer medicines than Caucasian women, possibly due to genetic differences in how the body breaks down these drugs. This study will measure drug levels in the blood and look at genetic factors and nutrition to understand these differences. You may be eligible if: - You are a woman aged 18 or older - You are of Asian or Caucasian background - You have confirmed breast cancer (not spread to other organs) for which chemotherapy with AC, EC, or FEC regimens is recommended - Your blood counts and organ function are within acceptable ranges You may NOT be eligible if: - You need a dose adjustment from the standard chemotherapy dose - You have brain metastases (cancer that has spread to the brain) - You have active infection, inflammatory bowel disease, or an uncontrolled autoimmune condition - You have another active cancer - You are allergic to any of the study drugs Talk to your doctor about whether this trial might be right for you.