Gefitinib With or Without Tamoxifen in Treating Patients With Tamoxifen-Resistant Metastatic Breast Cancer

RATIONALE: Gefitinib may stop the growth of tumor cells by blocking the enzymes necessary for their growth. Hormone therapy using tamoxifen may fight breast cancer by blocking the use of estrogen by the tumor cells. Combining gefitinib with tamoxifen may be effective in killing tumor cells that have become resistant (stopped responding) to tamoxifen. PURPOSE: This randomized phase II trial is studying how well giving gefitinib together with tamoxifen works compared to gefitinib alone in treating patients with metastatic breast cancer that has stopped responding to tamoxifen.