In patients with early-stage breast cancer, chemotherapy has substantially improved survival rates. Improvements in outcomes, however, are compromised by the considerable toxicities associated with chemotherapy, the most notable being neutropenia. Neutropenia is the presence of abnormally few white blood cells, leading to increase susceptibility to infection and can require hospitalization and need for intravenous antibiotics and is sometimes fatal. Febrile neutropenia (FN) can also be associated with treatment delays and dose reductions, potentially compromising treatment efficacy. Patients can receive medication to reduce the risk of FN such as Neupogen (filgrastim) as a daily injection for 5, 7 or 10 days. Since there is genuine uncertainty among healthcare professionals as to which administration schedule of Neupogen is the best for patients, the investigators are performing a randomized study for which patients will receive either 5, 7 or 10 days of Neupogen. Neupogen can cost approximately $200/injection, so if a physician prescribes 10 days for 8 cycles of treatment, this can cost $16,000 compared to a 5 day treatment which would cost half this. In addition to cost savings, many patients are not able to give themselves injections on a daily basis and require nursing resources which are utilized at high cost. This study will use an oral consent model to compare 5, 7 and 10 days of Neupogen to evaluate rates of febrile neutropenia and hospitalization.

Inclusion Criteria:

• Histologically confirmed primary breast cancer
• Planned to start docetaxel component of FEC-D or AC-D, or first cycle of; dose-dense AC-T, TC, FEC-D or TAC chemotherapy
• ≥19 years of age
• Able to provide verbal consent

Exclusion Criteria:

• Contraindication to Filgrastim

There is no plan to make IPD available.