Phase II Trial of Simple Oral Therapy (Continuous Oral Cyclophosphamide and Capecitabine) in Patients With Metastatic Breast Cancer

Must have pathologically confirmed diagnosis of metastatic breast cancer (M1) or multiple sites of new disease that is clinically obvious metastatic disease (i.e. multiple sites of new osseous disease); must have completed prior chemotherapy at least 14 days prior to registration; may have had 0, 1, or 2 prior chemotherapy regimens for metastatic disase, and no prior capecitabine or oral cyclophosphamide for metastatic disease; ER+ patients must have progressed on at least one hormonal therapy in the metastic setting; must not have symptomatic brain or CNS metastases; may have previously treated brain or CNS metastasis w/ radiation completed at least 8 weeks prior to registration; prior radiation to places other than CNS disease must be completed at least 14 days prior to registration; any number of prior radiation therapy regimens is allowed provided all toxicity of prior therapy is resolved; must have measurable disease or non-measurable disease, but MUC-1 antigen level is > 2 X ULN and MUC-1 antigen level has been documented to have increased by 1.5X prior to registration; must have MUC-1 antigen (either CA 15-3 or CA 27-29) level documented within 14 days of registration; planned clinical management of the patient should not include any concurrent antineoplastic therapy for breast cancer, however, bisphosphonates are allowed; PS=0-2; must not have active infection requiring systemic therapy; must have adequate renal function as documented by a calculated creatinine clearance > 40 mL/min; must not have prior unanticipated severe reaction to fluoropyrimidine therapy, or known sensitivity to 5-flurouracil or known DPD deficiency; must not have an inability to take oral medications (e.g. uncontrolled nausea, vomiting, diarrhea at baseline, lack of physical integrity of the upper GI tract, or malabsorption syndrome); must not have clinically significant cardiac disease (e.g. congestive heart failure, symptomatic coronary artery disease, and cardiac arrhythmias not well controlled with medication) or myocardial infarction w/in the last 12 months; must not require full dose coumadin therapy or a known, existing uncontrolled coagulopathy; must be 18 years of age or older; no prior malignancy is allowed except for adequately treated basal cell (or squamous cell) skin cancer, in situ cervical cancer, or other cancer for which the patient has been disease-free for five years; female patients must not be pregnant or nursing; women/men of reproductive potential must agree to use an effective contraceptive method.