Cyclophosphamide, Paclitaxel, and Trastuzumab in Treating Stage I-II HER2/Neu Positive Breast Cancer After Surgery

PRIMARY OBJECTIVES: I. To determine the toxicities and ability to complete the planned treatment of a dose-dense regimen of cyclophosphamide and paclitaxel with trastuzumab in subjects with newly diagnosed stage I-II HER2/neu positive breast cancer. II. To estimate recurrence free survival of a dose-dense regimen of cyclophosphamide and paclitaxel with trastuzumab in subjects with newly diagnosed stage I-II HER2/neu positive breast cancer. OUTLINE: SYSTEMIC THERAPY: Patients receive cyclophosphamide intravenously (IV) over 1 hour, paclitaxel IV over 3 hours, and trastuzumab IV over 30-90 minutes on day 1. Treatment repeats every 14 days for 6 courses in the absence of disease progression or unacceptable toxicity. MAINTENANCE TRASTUZUMAB THERAPY: Beginning in course 6, patients receive trastuzumab IV over 30-60 minutes on day 1. Treatment repeats every 21 days for up to 52 weeks in the absence of disease progression or unacceptable toxicity. Patients may undergo radiation therapy at the discretion of the radiation oncologist and medical oncologist and patients with estrogen/progesterone receptor positive tumors receive hormonal therapy as determined by the medical oncologist per standard National Comprehensive Care Network (NCCN) guidelines. After completion of study treatment, patients are followed up every 3 months for 2 years.