Patient description: The patient is a 42 year-old postmenopausal woman who had a screening sonogram which revealed an abnormality in the right breast. She had no palpable masses on breast exam. Core biopsy was done and revealed a 1.8 cm infiltrating ductal breast carcinoma in the left upper outer quadrant. Lumpectomy was done and the surgical margins were clear. The tumor was HER2-positive and ER/PR negative. Axillary sampling revealed 1 positive lymph node out of 12 sampled. CXR was unremarkable. She is using “well women” multivitamins daily and no other medication. She smokes frequently and consumes alcohol occasionally. She is in a relation with only one partner and has a history of 3 pregnancies and live births. She breastfed all three children.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Breast Cancer Women with pathologically demonstrated breast cancer Patients must be candidates for neoadjuvant paclitaxel chemotherapy by their treating oncologist. Generally this would Women with node-positive breast cancer based on ultrasound-guided axillary node biopsy, regardless of hormone or HER2 receptor status Women with greater than 1 cm breast cancer on imaging (mammogram, ultrasound, breast MRI) who are HER2+ or triple negative (ER-PR-HER2-) Women who are candidates for standard paclitaxel chemotherapy from treating oncologist for any other reason Patients must not have metastatic disease on staging work-up with chest imaging, CBC, and liver function studies A formalin-fixed paraffin embedded tumor block (preferred) or unstained slides must be available from a prior biopsy of the primary tumor. A minimum of 5 unstained slides must be available The primary tumor must be readily able to be biopsied by palpation The primary tumor must be measurable by an imaging modality prior to treatment. This imaging modality is to be repeated after completion of 4 cycles of paclitaxel and prior to surgery. Such imaging modalities may ultrasound, CT, mammography, or MRI. MRI will be the preferred imaging modality Subjects may not have had prior systemic chemotherapy or targeted therapy regimens administered for treatment of their current breast cancer  Patients who have had systemic chemotherapies, targeted therapies or radiotherapy for any cancer within 5 years prior to entering the study History of allergic reactions attributed to compounds of similar chemical or biologic composition to paclitaxel including to other drugs formulated in Cremophor(R) EL (polyoxyethylated castor oil) Patients with known HIV due to concern that chemotherapy may cause further immunosuppression and potential infectious complications Patients on non-aspirin anti-coagulation (Coumadin, heparins, or clopidogrel) or with documented bleeding disorders will be excluded due to risk of bleeding with biopsy Uncontrolled intercurrent illness including, but not limited to, ongoing or active severe infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, other malignancies requiring therapy or psychiatric illness/social situations that would limit compliance with study requirements Pregnant women are excluded from this study because paclitaxel is a pregnancy category D drug and may cause deleterious effects to the fetus. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with paclitaxel, breastfeeding should be discontinued if the mother is enrolled in the trial