ERBB2 and breast carcinoma: For the breast cancer cases for whom receptor status of tumors was available, 20 of 23 (87%) were estrogen receptor (ER)–positive, 19 of 22 (86.4%) were progesterone receptor (PR)–positive, and 6 of 12 (50%) were human epidermal growth factor receptor 2 (HER2)–positive.