DISEASE CHARACTERISTICS: Histologically confirmed adenocarcinoma of the breast with previous manifestations of progressing regional or metastatic cancer Received one prior systemic chemotherapy regimen for the treatment of metastases, which meets all of the following criteria: Included either doxorubicin, a taxane (i.e., paclitaxel or docetaxel), or both 6-8 courses were given If weekly taxane therapy received, at least 12 doses were given Recovered from all related toxic effects (except alopecia and/or neuropathy) 3-6 weeks have elapsed since last course of chemotherapy was given No more than 40 weeks have elapsed since the first dose of chemotherapy for metastases No current or prior history of brain metastases Responding or stable disease since the initiation of systemic chemotherapy (i.e., no disease progression) required No prior enrollment on ECOG trials for metastatic disease