Inclusion Criteria:  Stage 1-3 breast cancer Planned neoadjuvant, adjuvant, or curative intent paclitaxel 80 mg/m^2, 1-hour infusion (note: combination treatment, e.g., trastuzumab, pertuzumab, carboplatin, or pembrolizumab, and prior treatment, e.g., doxorubicin and cyclophosphamide, are allowable. Evaluable computed tomography (CT) scan, e.g., scan of the chest, abdomen, or pelvis for any indication within 1 year. Adequate organ function based on paclitaxel label. Ability to understand and the willingness to sign a written informed consent.  Exclusion Criteria:  Concomitant administration of any moderate or strong inducer or inhibitor of CYP2C8, including rifampin or clopidogrel. History of hypersensitivity reaction to paclitaxel or any components of paclitaxel (e.g., Cremophor EL) that precludes continued treatment with standard dose and infusion length Pregnant or nursing