This open-label, multicenter study explored primary and secondary prophylaxis treatment with a single, fixed-dose, subcutaneous (SC) injection of pegfilgrastim in elderly subjects with high-risk breast cancer receiving myelosuppressive chemotherapy. The primary objective was to provide preliminary information on the incidence of protocol defined neutropenic events in chemotherapy cycle 1.

Inclusion Criteria: - High-risk, stage II-III breast cancer suitable for treatment with up to 6 cycles of FEC-100 - Chemotherapy - Histologically proven greater than or equal to 1 axillary nodes positive - Oestrogen receptor negative or positive - Chemotherapy naïve - VES 13 (Vulnerable Elders Survey) score less than or equal to 3 - ECOG performance status less than or equal to 2 - ANC greater than or equal to 1.5 x 10^9/L - Platelets greater than or equal to 100 x 10^9/L - Adequate renal function (serum creatinine less than 1.5 x upper limit of normal (ULN)) - Before any study specific procedure the subject must give written informed consent for participation in the study Exclusion Criteria: - Total serum bilirubin greater than ULN according to institutional standard - Clinically significant cardiac disease that would preclude the use of epirubicin (e.g., LVEF (left ventricular ejection fraction)) less than 45% at rest by MUGA or echocardiogram - Prior bone marrow or stem cell transplantation - Any premalignant myeloid condition or any malignancy with myeloid characteristics (e.g., myelodysplastic syndromes, acute or chronic myelogenous leukaemia) - History of prior malignancy other than breast cancer with the exception of curatively treated basal cell carcinoma, in situ cervical carcinoma or surgically cured malignancies - Prior radiation therapy - Active infection or administration of systemic antibiotics or anti-infectives within 72 hours before start of chemotherapy - Known hypersensitivity to E coli-derived products (e.g., Filgrastim, HUMULIN®, Insulin, L-Asparaginase, HUMATROPE®, Growth Hormone, INTRON A®) - Previous exposure to pegfilgrastim or previous entry into this study - Known HIV infection - Inability to understand the nature of the study and provide written informed consent - Subject currently enrolled in another investigational device or drug trial(s) or has received other investigational agent(s), with the exception of placebo-treated subjects, within the last 30 days - Concerns for subject's compliance with the protocol procedures