The serum protein research study is a substudy of the core study 'Maintenance Chemotherapy
in Hormone Non-responsive Breast Cancer'. This substudy is an evaluation of blood proteins
and their relationship to breast cancer treatment. It will assess the levels of Vascular
Endothelial Growth Factor (VEGF), Soluble HER2 Protein (NRP, neu-related protein) and
Vascular Cellular Adhesion Molecule-1 (VCAM-1) in serum samples of patients' blood at
different time points. The goal is to evaluate differences in serum levels between patients
receiving the maintenance chemotherapy and those who do not. The serum levels will be also
examined to determine if they vary during the three year period of evaluation. In addition,
the serum levels of patients who have a recurrence of their breast cancer will be compared
with those who remain disease free. The information obtained from these studies will enable
breast cancer physicians to better tailor therapies for future patients.