 This phase II trial studies how well giving lapatinib ditosylate together with tamoxifen citrate works in treating patients with breast cancer that has spread from where it started to nearby tissue or lymph nodes or to other areas of the body and did not respond to previous treatment with tamoxifen citrate. Lapatinib ditosylate may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Estrogen can cause the growth of breast cancer cells. Hormone therapy using tamoxifen citrate may fight breast cancer by blocking the use of estrogen by the tumor cells. Sometimes when tamoxifen citrate is given, it does not stop the growth of tumor cells. The tumor is said to be resistant to tamoxifen citrate. Giving lapatinib ditosylate together with tamoxifen citrate may reduce drug resistance and allow the tumor cells to be killed. 