Cabergoline in Metastatic Breast Cancer

Inclusion Criteria

• •Patients must have histologically confirmed metastatic breast cancer; tissue (a minimum of 3 slides) from the most recent biopsy is required for review and confirmation of eligibility; NOTE: material should ideally be from the metastatic disease, however material from the primary tumor is acceptable if that is all that is available
• •Patients must have stage IV breast cancer
• •Patients must have tumors (primary or metastatic) that stain positively for the prolactin receptor
• •Patients may have measurable or evaluable disease
• •* Measurable disease is defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded) as \> 20 mm with conventional techniques or as \> 10 mm with spiral CT scan
• •* Evaluable disease is disease that does not meet the criteria for measurable disease; examples would include patients with effusions or bone-only disease
• •Women of childbearing potential must commit to the use of effective barrier (non-hormonal) contraception while on study
• •Patients must have a life expectancy of greater than 12 weeks
• •Patients must have an Eastern Cooperative Oncology Group (ECOG) performance status =\< 2
• •Patients may have had a prior diagnosis of cancer if it has been \> 5 years since their last treatment
• •Leukocytes \>= 3,000/uL (microliter)
• •Absolute neutrophil count \>= 1,500/uL
• •Platelets \>= 100,000/uL
• •Child Pugh score =\< 10
• •Patients must be able to swallow and retain oral medication
• •All patients must have given signed, informed consent prior to registration on study