Receptor status in breast cancer that has recurred or metastasized may be different from the original tumor, according to research presented at the 2010 ASCO meeting in San Antonio. Estrogen-receptor status changed in 33 percent of breast cancer patients; Her2 status changed in ten percent, in a study of 459 patients by Swedish researchers. Twenty-six percent of tumors changed from positive to negative and seven percent changed from negative to positive. In previous research, published in the journal Breast Cancer Research, ten percent of all tumors changed receptor status. Internal Medicine News has the story.