Studying Blood Samples in Women With Breast Cancer or a History of Breast Cancer

OBJECTIVES: Primary * To compare peripheral blood (PB) concentrations of circulating endothelial cells (CEC) in women with measurable, active breast cancer to PB concentrations of CEC in a control population of women with a history of breast cancer who are currently without evidence of active disease. Secondary * To compare in women with measurable breast cancer the relationship between PB concentrations of CEC prior to and at 3 and 6 weeks following initiation of a new chemotherapy or hormonal therapy, and correlate these values with clinical response to treatment to determine if CEC can be used as a tumor marker or indicator of disease burden. * To compare PB concentrations of CEC to levels of plasma proteins associated with angiogenesis, including vascular endothelial growth factor, in women with active or a prior history of breast cancer. OUTLINE: Peripheral blood and plasma samples are collected for analysis of circulating endothelial cells (CEC) and angiogenic growth factor levels. Blood samples from patients initiating a new chemotherapy or hormonal therapy for breast cancer are collected at baseline and at 3 and 6 weeks following the start of treatment. CEC are quantified via flow cytometry and plasma angiogenic markers are assessed via ELISA. PROJECTED ACCRUAL: A total of 100 patients with active, measurable breast cancer and 100 patients with a prior history of breast cancer will be accrued for this study.