Effect of Neoadjuvant or Adjuvant Systemic Therapy on Breast Cancers, Bone Marrow Cancer Cells, and Circulating Cancer Cells

This study examines how chemotherapy or hormone therapy given before or after breast cancer surgery changes the biology of breast tissue, aiming to understand which treatments work best and why. **You may be eligible if...** - You have been diagnosed with breast cancer and are scheduled to receive chemotherapy or hormone therapy before or after surgery - You are willing to have additional tissue samples collected during your scheduled surgery - You are 18 years of age or older **You may NOT be eligible if...** - You are not receiving systemic therapy (chemotherapy or hormonal treatment) as part of your breast cancer care - You have already completed all planned treatments - You have a bleeding disorder or other condition that makes tissue sampling unsafe Talk to your doctor to see if this trial is right for you.